s06g02-strum-yearbook 2012.pdf

Darwin’s Monkey: Why Baboons Can’t Become HumanShirley C. Strum1,2,3*

1Department of Anthropology, University of California, San Diego, La Jolla, CA 92093-05322Uaso Ngiro Baboon Project, Box 62844, Nairobi, 00200, Kenya3Institute of Primate Research, National Museums of Kenya, Box 24481-00502, Karen, Nairobi, Kenya

KEY WORDS baboons; Papio anubis; natural history; complexity; negotiation; dominance;collaboration; natural selection; human evolution; Anthropocene

ABSTRACT Baboons were used in the past as mod-els for human evolution. I utilize 40 years of data frommy long-term study on baboons in Kenya to suggest thatbaboons are once again relevant for understandinghuman evolution, not as a referential model but to resetthe starting conditions of the human experiment. Thebaboon data also offer a critique of widely held ideasabout how natural selection might work by looking atreal lives in real time. This situates competition in a ma-trix of collaboration and illustrates the critical role ofchance, contingency, and history in baboon survival andsuccess. I make three methodological moves to reachthese conclusions. The first is to focus on process notjust outcome. The second is to look at time scales longerthan usual studies but shorter than evolutionary time asa way to open the black box that currently links behav-ior to evolutionary value. The third is to use compara-tive natural history, Darwin’s method, as a way to cap-ture and comprehend how complexity is generated andhow baboons deal with it in their daily lives. These em-pirical and methodological turns lead to conclusions thatrun counter to widely held ideas about baboons, aboutprimates, and about the determinism of natural selec-tion. I follow my own research history to illustrate thesepoints. The discussion ranges from alternative interpre-tations of the male and the female dominance hierar-

chies, to insights from a fission that happened when theforaging strategy of raiding and nonraiding baboonsdiverged, to evidence of adaptation after translocation,and finally to assessing two unusual fusions of baboongroups. Altogether, these natural histories yield baboon‘‘principles of the social’’ with insights about cognition,cooperation, and culture and suggest why baboons can’tbecome human. The data also support Weiss andBuchanan’s framework (The Mermaid’s Tale: Four Bil-lion Years of Cooperation in the Making of LivingThings. Cambridge, MA: Harvard University Press,2009. 305 p) with its alternative view of natural selec-tion in which there is more slippage and tolerance, mul-tiple solutions with larger acceptability spaces, and thepossibility that an adaptive fit will be ‘‘good enough’’rather than seamless. However, capturing behavioralcomplexity ‘‘in the wild’’ poses methodological challenges.Long-term field studies provide critical information butthe current quantitative methods should be expandedalso include natural history observations of behaviorsand events across time, space, groups, and landscapes.Finally, the baboon natural histories illustrate how theevolutionary game has changed in the Anthropoceneyielding a cautionary tale about the future for manyprimate species. Yrbk Phys Anthropol 55:3–23, 2012.VVC 2012 Wiley Periodicals, Inc.

Baboons have played a central role both in our under-standing of primates and as models for human evolutionbeginning with Zuckerman’s 1932 description of primatesociety. Based on his observations of Hamadryas baboonsat the London Zoo, he argued for a society founded onsex, violence, and male domination of both females andmales (Zuckerman, 1932, 1933). Zuckerman can be for-given for his mistakes because we knew very little aboutprimates in nature at that time (Strum and Fedigan,2000b). Baboons continued to capture the scientific (andpublic) imagination three decades later through theearly scientific work on savanna baboons done byWashburn, his student, DeVore, and the English psychol-ogist, Hall (DeVore, 1965). Once again baboons becameemblematic of evolution; however, this time it was the fitbetween behavior and anatomy which told a convincingstory about how natural selection worked (Washburnand DeVore, 1961, 1963; DeVore and Hall, 1965; Halland DeVore, 1965; Strum and Fedigan, 2000b). Evolutiongave male baboons the anatomy of aggression. Baboonmales used those remarkable canines, large body size,impressive mantle of hair, and white eyelids in displaysduring sexual competition with other males and againstpredators. Fighting ability determined male rank whichin turn governed reproductive success so that the best

males were the most reproductive. The male dominancehierarchy also was the political structure of the group; itordered male interactions reducing the need for frequentaggressive encounters. Males defended and policed;females raised babies. Males were central to all majorgroup functions, whereas females were defined in termsof their relationships with males. Washburn and DeVore

J_ID: ZC0 Customer A_ID: YRBK.12.01 Cadmus Art: AJPA22158 Date: 7-NOVEMBER-12 Stage: I Page: 1

ID: senthilk Date: 7/11/12 Time: 17:43 Path: N:/Wiley/3b2/AJPA/Vol149S55/120155/APPFile/JW-AJPA120155

Grant sponsors: National Science Foundation, Wenner-GrenFoundation for Anthropological Research, University of California,San Diego, National Geographic Society, Fyseen Foundation, Wild-life Conservation International, LSB Leakey Foundation, Art Orten-berg and Liz Claiborne Foundation, African Conservation Centre,African Conservation Fund.

*Correspondence to: Shirley C. Strum, Department of Anthropol-ogy, University of California, 9500 Gillman Drive, San Diego, LaJolla, CA 92093-0532, USA. E-mail: [email protected] (or)[email protected]

Received 6 September 2012; accepted 7 September 2012

DOI 10.1002/ajpa.22158Published online 17 October 2012 in Wiley Online Library

(wileyonlinelibrary.com).

VVC 2012 WILEY PERIODICALS, INC.

YEARBOOK OF PHYSICAL ANTHROPOLOGY 55:3–23 (2012)

(1961) argued that we could infer the challenges that thesavanna presented to a puny primate living away fromthe safety of the forest (read hominids) by lookingthrough the lens of the only other primate that managedto do so successfully, baboons.

What follows is not a scholarly review of the baboonliterature and its relevance to human evolution.Instead, I was invited to discuss my insights aboutbaboons based on 40 years of observing them in thewild. Baboons have long since been dethroned as ‘‘the’’preferred species, first by common chimpanzees(Goodall, 1988/1971) and then by bonobos (Zihlman,1978; Kano, 1992; Strum and Fedigan, 2000b). In con-trast, I will suggest that baboons are once again rele-vant for those interested in human evolution but innew ways. What follows is an argument that is mainlybottom up, grounded in baboon observations. In theend, I hope to illustrate that the baboons I have studiedlive in the most complex nonhuman primate society yetdescribed and that they reside in the most socioecologi-cal complexity documented so far for a nonhuman pri-mate. Furthermore, these baboon data suggest that fo-cusing on real time and real lives provides a differentview of how evolutionary processes work. Chance, con-tingency, and history play an important role in survivaland success. This offers a critique of widely held ideasabout natural selection, particularly the centrality ofcompetition. The data also argue for the existence ofmultiple options (including ‘‘mistakes’’) made possible bythe intelligence and social skill that baboons use tobuild their primate society. I am often asked why, ifbaboons are so smart, they aren’t human. There aremany things wrong with the way this question isphrased. However, the perspective I present below doesadd a new factor to the list of obvious differences: theimportance of managing complexity in daily life.

To reach these conclusions, I made three critical meth-odological moves. The first was to focus on process notjust outcome. The second was to look at time scales longerthan usual studies but not collapse everything into evolu-tionary time. The third was to use comparative naturalhistory, Darwin’s method. Primate studies rejected natu-ral history observations when growing knowledge aboutprimates grew and more sophisticated data collectionmethods were available (Strum and Fedigan, 2000a). Fornow, however, natural history may be the only way tocapture and comprehend how complexity is generatedand how baboons deal with it in their daily lives.

These empirical and methodological turns lead to con-clusions that run counter to widely held ideas aboutbaboons, about primates, and about the determinism ofnatural selection. This is not simply an emphasis onproximate rather than ultimate levels of causal explana-tion (Tinbergen, 1963). Instead, it tries to open the blackbox linking behavior and evolutionary outcome andraises the question of what can be legitimately assumedabout shorter time scales when we make evolutionarytime arguments. I do not review the extensive literatureon all these topics. Instead, I include key references as astarting point for readers interested in exploring further.

My reference species is olive baboons, Papio anubis(Zinner et al., 2009). The reference material is the 40years of my own research (see Strum and Fedigan,2000b) for a framework to situate most of these years). Itrack individuals, relationships, and social groups in twopopulations. The baboons lived in two locations because Itranslocated three groups in 1984 (Strum and Southwick,

1987; Strum, 2005). Translocation was an experimentthat provided persuasive evidence about baboon adapta-bility. The new location, arid savanna occupied by no-madic pastoralists, has had both natural cycles of extremeevents like droughts and in the last decade, human-induced changes that also created extreme events. Else-where (Strum and Western, 1982), I have argued that thebaboons don’t distinguish between the sources (naturalvs. human) of environmental change in their responses tochange. This is particularly relevant to the scale and theprocesses I will explore. In this presentation, I touch onareas that are minefields of controversy, for example,what is culture or tradition and what is cooperation. For-tunately, my argument does not depend on resolvingthese controversies, a task I leave to others.

In this article, I move through a series of steps thatreflect my own research history rather than their orderof importance. During this time, I have gone from mak-ing baboons ‘‘almost human’’ by focusing on their socialnegotiation and politics (Strum, 2001/1987a) to under-standing better why baboons ‘‘aren’t human.’’ I have col-lected quantitative data for four decades; however, I findthese data inadequate to make sense of what thebaboons are doing. Instead, I turn to comparative natu-ral history for the missing insights. The title ‘‘Darwin’sMonkey’’ refers both to the importance of Darwin’s meth-odology as well as his prescient observations of baboons(Darwin, 1871/2004).

My over-arching goal, in this article and in myresearch, is to recapture the complexity that exists in ba-boon lives and then to consider the implications of thiscomplexity for evolutionary interpretations and for ourcurrent scientific practice. I end with a discussion of whyunderstanding baboons is important for [physical/biologi-cal] anthropologists today.

PART 1: GENERATING COMPLEXITY

Remodeling the male dominance hierarchymakes baboons ‘‘almost human’’ (1972–1980)

It is hard to believe in the 21st century how little weknew about primate behavior in the 1960s and how rudi-mentary were our methods. The pioneering work of the‘‘classical ethologists’’ like Tinbergen, Lorenz, and vonFrisch starting in the 1930s (Tinbergen, 1942, 1963; Lor-enz, 1950) did two key things. It critiqued (previous)anthropomorphic interpretations of behavior and createda novel methodology that still relied on natural history[ethogram, fixed action patterns; critical periods; andinteraction of field data with captive experiments (Tin-bergen, 1974/1951)].

When primate field studies resumed after World War2, scientists still used natural history descriptions butadded the ‘‘ethogram,’’ a careful and detailed descriptionof the behavior of that species (or group, or popula-tion. . .these terms were interchangeable then). In themiddle of last century, there were only dozens of studiesof primates in the wild, not hundreds, and only a fewspecies had been observed in more than one location(DeVore, 1965; Altmann, 1967; Jay, 1968).

Variation in behavior seemed minimal, making broadgeneralizations about primate patterns seemed war-ranted (Washburn and DeVore, 1961; Strum and Fedi-gan, 2000b). However, by the early 1970s, variation inbehavior and social organization began to accumulate.For example, patas monkeys solved the problems of sa-vanna living with an anatomy adapted for rapid escape



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Yearbook of Physical Anthropology

and behavior adapted for vigilant diversionary malesand stealthy females and young (Hall, 1968). WhileWashburn and DeVore’s dominant males strode out toface a predator, Rowell’s male baboons were the first torun to the trees, leaving the females and youngstersexposed (Rowell, 1966). Natural history methods werenecessary whenever a new species was studied; however,disagreements of ‘‘fact’’ were hard to resolve. Were theanimals really different or were differences an artifact ofobservers and ways of observing?

When I began my baboon study on male and femaleroles in olive baboon society (1972–1974, Kekopey nearGilgil, Rift Valley, Kenya), there was already evidencefrom rhesus macaques on Cayo Santiago Island in the Ca-ribbean that females, as well as males, had a dominancehierarchy and that matrilineal relationships were thecore of the group (Sade, 1967, 1972). As well, there was amove to use more systematic ways of data collection inthe field [well summarized by Jeanne Altmann’s oftencited paper (Altmann, 1974)]. All baboon projects from theearly 1970s onward inherited a baboon ethogram fromHall, Washburn, DeVore, Rowell, and Ransom (Washburnand DeVore, 1961; DeVore and Hall, 1965; Hall andDeVore, 1965; Rowell, 1966; Ransom, 1981). This meantthat the data included the same basic elements of behav-ior. When possible (meaning in contexts where the prima-tes could actually be seen), investigators relied on focalanimal samples (follows for a fixed duration of randomlychosen individuals) as a way to minimize bias.

I collected my data this way. The results confirmedthat matrilines (female based families) were the core ofthe group and that a matrilineal dominance hierarchywas the troop’s main structure. Families, rather thanjust adult males, protected and policed the group onbehalf of their own members. Females had ‘‘political’’functions besides motherhood (see also Hausfater, 1975;Ransom, 1981).

However, the ‘‘males’’ I studied didn’t behave as pre-dicted. The category ‘‘males’’ includes large adolescentsreaching the asymptote of their growth (Strum, 1991)and fully adult males ranging in age from young ([10years) to old (more than 20 years). Hausfater, on yellowbaboons in Amboseli National Park in Kenya (Hausfater,1975; Hausfater et al., 1982), documented a relativelystable male dominance hierarchy that operated as pre-dicted. The dominant male(s) had priority of access tolimited resources and mating opportunities. TheHausfater study was a careful and quantitative refine-ment of the previous baboon model. By contrast, I foundmale rank relationships exceedingly dynamic (Strum,1982). Individuals spent time and energy working ontheir relationships with each other and tracking thechanges in all male relationships. Processes of male mat-uration and male migration fueled the instability.

Besides its dynamic nature, the existing male hierar-chy did not correlate with access to resources such asreceptive females. Often rank did not even predict thewinner of an aggressive encounter (Strum, 1982). Thereason was that baboons, including the males, had alter-natives to aggression. These ‘‘social strategies of competi-tion and defense’’ (Strum, 1975a, 1976; Western andStrum, 1983) could be as effective and were less riskythan aggressive approaches. However, they depended ona number of factors for success. First, some relied on‘‘special’’ social relationships. Ransom (1981) identified‘‘special’’ relationships’’ between males and females andmales and infants in the Gombe Stream baboons in his

1967 study but hadn’t yet appreciated their function.Kekopey males created special relationships and laterused them to advantage. For example, males used younginfants as agonistic buffers against other males (Strum,1983c). Usually, it was the potential loser who got aninfant, returning to the protagonist with the baby on hisbelly. Most often, the aggressive male backed off. A malecould also use a female as a buffer (Strum, 1983b). Whydid it work?—because buffering allowed a male to mobi-lize troop support. Normally, other group members don’tget involved in male–male interactions. However, thegroup will mob a male whose aggression causes distressto infants and females. A pivotal element in buffering asa successful tactic is trust. Trust is a social construct forhumans and for baboons. It makes social life predictable,creates a sense of community, and makes it easier forindividuals to work together (Holmes and Rempel, 1989;Misztal, 1996, 2001; Rousseau et al., 1998; Kappeler andvan Schaik, 2006; Henrich et al., 2009; Sueur et al.,2011b). In economics, trust is a way to reduce transac-tion costs, creating new forms of collaboration and it is aform of social capital. For baboons in the context of ago-nistic buffering, trust implies a particular social history.It means that the male has been predictably affiliativewith the infant. Both the infant and the male haveexpectations of each other based on their social history.If the buffer trusts the male friend, it will scream at theaggressive opponent. Without trust, a male runs the riskof himself becoming the object of mobbing if the infantscreams at him rather than at the opponent. Thisimplies that the social relationship comes first; using therelationships in a social strategy comes later.

Males got other benefits from friendships withfemales. Following ethological tradition, I refrained fromcalling special relationships ‘‘friendships’’ until I wasconvinced that baboon and human friendships sharedmany characteristics (the term special relationship wasreplaced by the term ‘‘friendship’’ in the literature begin-ning in the 1980s). There is no rape among baboons, andtherefore, while males might fight to get a temporarilyexclusive association with a sexually receptive female, or‘‘consort,’’ the consort male needs the female’s coopera-tion to successfully copulate with her. Consorts mayattract many male ‘‘followers.’’ Friendship between theconsort male and female also influenced whether a malecan keep the consort in the face of pressure from fol-lower males (Smuts, 1985; Strum, 2001/1987b).

Other social tactics relied on social knowledge andassessment skills. For example, older males with lessaggressive potential still got consorts and copulations.One way was through a maneuver I called ‘‘sidelines.’’ Insidelines, a male monitors the consort from a distance.He makes his move when aggression breaks out betweenthe consort male and his close followers. Then, the moredistant monitoring male dashes to the female. By thetime the male aggression is over, the older male hascopulated with the female (becoming her new consort),has skillfully led her away from the other males, and isdeftly grooming her. Ironically, another avenue for maleswith little aggressive potential is to manipulate aggres-sion between consort male and followers. He can do thisas a follower or from the sidelines, escalating aggressionby his involvement but usually leaving before anothermale turns on him.

An individual’s age and length of residency in thetroop predicted whether he used aggression or socialstrategies as well as his success (Strum, 1978, 1982). All



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males followed the same social trajectory through theirlife history from socially unskilled maturing male withgrowing physical powers (using aggressive strategies) tothe socially skillful mature male whose success dependsentirely on social expertise when he is old (using socialstrategies of competition and defense).

Males weren’t the only beneficiaries of social strat-egies. Infants and females could rely on the support oftheir male friend when aggression was directed at them.Even the close proximity of a male friend reduced socialinterference that a female or infant would receive basedon rank and age.

Complexity 1: Social strategies in addition toaggressive strategies create multiple options

Science makes simplifying assumptions to be able tobegin studying complex phenomena such as social inter-actions. The problem comes when the results of thoseinvestigations slide into thinking that such systems aresimple. Uncoupling the tight link between male domi-nance rank and male evolutionary payoffs was the firstevidence I had of social complexity among baboons.Baboons created and managed special relationships.They adjusted their behavior based on expectations frompast interactions (Strum, 2008). Social strategies werealso evidence of social collaboration (see section on col-laboration later) and exchange. Among baboons, eventhe physically impressive males needed the help of lessimposing individuals to succeed. Baboons, it seemed, hadno option but to play by the ‘‘golden rule.’’

At this point in my research, negotiations betweenbaboons stood out in bold relief. Human negotiation isusually a ‘‘dialog’’ between two or more individuals. Thedialog aims for a common understanding about a courseof actions that satisfies the interests of the partiesinvolved (Homans, 1958; Festinger, 1985/1957; Misztal,2001; Raiffa, 2003/1982; Pearce and Hans-Werner, 2008;West and Turner, 2009). I saw baboon negotiations as be-havioral conversations about investments in, and payoffsof, special relationships. Clearly, such interactions selectfor very different skills than would aggressive competi-tion in, for example, mating success (see also Sussmanand Garber, 2011). The conclusion: a primate with a bigbrain can create more alternatives than previous evolu-tionary models suggested. I argued that these kinds ofnegotiations, social strategies, and sexual politics madebaboons ‘‘almost human’’ (Strum, 2001/1987b).

A brief note about my use of the term ‘‘complexity’’ iswarranted. The study of social complexity has generateda huge literature since these first baboon observations(e.g., see Byrne and Whiten, 1989; Whiten and Richard,1997; de Waal and Tyack, 2003; Cheney, 2007). Despitethis, there is no clear definition of social complexity(Strum et al., 1997). Whiten (2000) suggested that socialcomplexity must include the dimensions of variability ofresponse, size of group, number of relationships, instabil-ity, and predictability. Dunbar (1998) found a strong cor-relation between group size. Ironically, Robert Hinde’s1970’s model of interacting levels that moves from indi-viduals to interactions to relationships to group structureis probably the best approximation to an operationalizeddefinition of social complexity [Hinde, 1976, 1987; andsee Forster and Rodriguez (2006) for an example of howthis would work]. In another section, I offer a specific def-inition of baboon social complexity. Until that point, I usedata to build the dimensions of baboon complexity anduse an everyday definition of complexity: being intricate,

a system with numerous elements and many forms ofrelationships which are all ‘‘entwined (Latin ‘‘com-plexus’’); complex systems have more parts and more con-nections than simple ones (Dictionary, 1971).

Remodeling socioecology: Group size does notdetermine group fission (1981–1984)

Today, group size is thought to be a trade-off betweenthe advantages (predator protection, resource discovery,and for primates, traditional knowledge of resources) anddisadvantages (feeding competition and inefficiency) ofliving in a large group when compared with small group(Wrangham, 1980; van Schaik, 1983; Isbell, 1994; Isbelland Young, 2002). Group fission happens regularlyamong baboons (although there is a dearth of publishedinformation: for baboons, see Stoltz, 1972; Nash, 1976;Hamilton and Bulgar, 1993; Henzi et al., 1997; Wasser etal., 2004; Van Horn et al., 2007; but for macaques, seeFuruya, 1969; Chepko-Sade, 1974; Chepko-Sade andSade, 1979; Dittus, 1988; Kuester and Paul, 1997; Oka-moto and Matsumura, 2001; Kawamoto, 2010). Theoreti-cally, a group should split when it gets too large to forageeffectively (increased feeding competition and/or has totravel too far to feed that many individuals), or too largeto monitor and manage the many social interactions, orfor both reasons.

In 1981, the main study group, Pumphouse, fissioned.The split centered on a disagreement about foragingstrategies not about group size as Pumphouse was wellbelow the numbers recorded in other baboon fissions (seeabove). An agricultural cooperative bought KekopeyRanch, the study site, in 1976. Kekopey covered 45,000acres. Although it was a cattle ranch, there were fewcows, a large complement of wildlife, and minimal farm-ing potential. By 1981, small-hold farms (shambas)appeared in the baboons’ traditional home range. Thenhuman–baboon conflict began (Strum, 2001/1987b, 2010).Young adult and large adolescent Pumphouse maleswere the most motivated to raid. Troop movements awayfrom the sleeping sites included extensive negotiationsbetween these males and the rest of the group. Somedays, the raiders pulled the rest of the troop with thembut on other days they failed. Then only the raiderswent to the fields. There was a dramatic increase inanthropogenic injuries and deaths because of the conflict(Strum, 2010). Pumphouse spent over 6 months in theprocess of splitting. During this time, there were con-stant negotiations between raiders and nonraiders aswell as among family members of raiders and nonraidersas they decided which group they would join. In the end,Pumphouse, the larger descendent group remained pri-marily natural foragers, whereas the smaller descendentgroup (Wabaya) became dedicated raiders.

However, these weren’t the only responses. A thirdstudy group, Eburru Cliffs (larger than the other twoand having the largest home range), tried human food,sustained the costs of conflict, and then completely aban-doned the settlement area. They remained natural forag-ers using the part of their traditional home range thatwas as far away from the settled area as they could get(a distance of over 7 km as the crow flies).

Why raid? Human food offers significant benefits tobaboons. Both males and females grew faster, reachedadulthood earlier, and had heavier final weights (Strum,1991, 2010), a result found in other studies of food



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enhanced baboons (Altmann and Muruthi, 1988; Muru-thi et al., 1991; Altmann et al., 1993). Faster growthmeant earlier female reproduction. Although the samplesize is small, raider females reached menarche soonerand produced their first baby earlier than nonraiderfemales. Interbirth intervals were significantly shorterin raider females when compared with nonraiders. Anextreme example of this was the lowest ranking raiderfemale. Her fecundity increased significantly when shebecame a raider, which reversed her previous age-relatedreproductive decline. Infants who grew up in food-enhanced conditions reached menarche and first birthearlier even though these landmarks occurred after theywere translocated to a resource-poor environment. Infantsurvivorship did not differ between the raiders and non-raiders despite initially high rates of injury and deathassociated with raiding. With time, raiders adjusted tothe risks of being close to humans so that costs declined(Strum, 2010).

What were the baboons doing during those 6 months ofthe fission? The matriarch of the lowest ranking familyprovides one illustration. One day she would be with theraiders; the next day she was with the nonraiders. Thiswent on for months. Her already independent infant,who still closely associated with his mother, moved backand forth with her unlike the female’s adolescent sonswho remained with the nonraiders. Eventually, aftermany migrations back and forth, that female became apermanent member of the raiding troop but her infantdid not. He returned to the nonraiders and stayed withhis brothers. Months later, the matriarch’s subadultdaughter also became a member of the raider group.

Females could have several reasons for joining theraiding group, Wabaya. Most often, the emigratingfemale was following her closest male friend who hap-pened to be a ‘‘raider.’’ A female’s rank in her matrilinealso played a role. The females who left Pumphouse forthe raider group were most often the oldest daughtersand hence the lowest ranking females in their matriline.By joining the raider group, they traded kin support forthe benefits of male friendship and of raiding. They alsoavoided internal matrilineal disputes and reduced thenumber of females to compete with because Wabaya wassmaller. Three pairs of sisters transferred to the raidingtroop. The social framework that underpinned their pre-vious rank relationship to each other disappeared andtheir rank reversed in Wabaya. The older sister becamedominant to the younger one. By contrast, some thingsdidn’t change. Despite having only a few matrilines rep-resented in Wabaya, the original Pumphouse female hi-erarchy was perfectly reproduced albeit with somefemales missing.

Complexity 2: Context becomes history as baboonsnegotiate socioecology

The study troop did not split because it was too large.What had happened during the fission added evidenceabout the socioecological complexity of baboon lives.Most individuals selected not to raid despite the majordocumented benefits of the raiding lifestyle. Individualswith the same characteristics chose different paths. Tomy surprise, other factors trumped evolutionary princi-ples like optimal foraging and kinship as well as derivedprinciples like hierarchy.

Why didn’t all males become raiders? Large subadultand young adult males had the most to gain in terms ofgrowth and weight (and reproduction?) yet not all of

them made the switch. Not all females became raiders. Iexpect that the conservativeness of baboon femalesplayed an important role and for a few females a specialsocial relationship (friendship) with a raider male wasthe defining influence. However, even in this smallersubset, there were exceptions: the lowest ranking femaleand her daughter were not friends with any raider malewhen they joined the raiding group. Equally important,not all troops with the opportunity chose to raid.

Paying attention to the process, to the natural historyof events and individuals, showed me baboon complexitybeyond social strategies and added to my appreciation ofhow evolution works at the level of real lives.

Translocation: Survival depends on others not oncompetition between individuals (1984–2000)

Darwin relied on the idea of ‘‘survival of the fittest’’ toexplain evolution by natural selection (Darwin, 1859).Subsequent evolutionary interpretations of animal (pri-mate) behavior focused on competition as the key to indi-vidual survival. Sociobiology (Wilson, 1975) enlarged the‘‘individual’’ to include kin in the mid-1970s [inclusive fit-ness (Hamilton, 1964)], and recently, group selection hasbeen resuscitated as possible and important for humans(Richerson and Boyd, 2005; Leigh, 2010; Nowak et al.,2010; West et al., 2010). Usually, scientists infer whatbehavior is crucial to survival and reproductive success.By contrast, the translocation of the study baboonsbecame an actual test of survival where the process couldbe documented and the outcome could be measured.

Despite great success with crop-raiding research andcontrol techniques, in 1984, I had to translocate threetroops of wild baboons (Pumphouse, Wabaya—theraiders, and a third troop called Cripple who were alsoin conflict with people), a total of 132 individuals. Thiswas the first scientific translocation of a primate group(Strum and Southwick, 1987). The translocation pro-vided a unique opportunity to document adaptability(possibly adaptation) in action. I could compare the sameindividuals and the same troops in two radically differ-ent environments. The translocation site, on the EasternLaikipia Plateau, is arid savanna with half the annualrainfall of Kekopey, the baboons’ previous home. Seriousdroughts are common. The baboons were familiar withonly about half of the foods available in the new locationand the unknown ones turned out to be critical to sur-vival during seasonal bottlenecks. The release site wasnot ideal; however, it was the only site I could get.

The descendants of the translocated baboons are alivetoday. The process by which they survived providedmore evidence of the complexity of baboon life and illus-trated evolutionary raw material.

Primates are social; it is a key characteristic of theOrder. There are a number of theories about why mostprimates live in a social group (see above); however, it isdifficult to document the value of group living during thecourse of most studies. The baboon translocation pro-vided one chance. The benefits of living in an intactsocial group permeated almost every aspect of adjust-ment during the translocation.

To start, I manipulated existing social networks toensure that the troops stayed where they were released.I held adult males captive at the release site, whereasthe females and youngsters were set free. As expected,the females did not go far without the males. By thetime the males were released, the females had already



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settled in and female conservatism checked the maletendency to wander (Strum, 2002, 2005).

Each of the three troops was released in a differentplace and at different times. The troops maintainedcohesion and coordination from the first days of freedom.The group represented a social learning resource in amore basic sense than we usually assume. Individuals inthe translocated groups demonstrated flexibility in learn-ing in novel settings. Social cues figured prominently inthe process of acquiring information. For example, thetranslocated troops had to construct a diet in this unfa-miliar place. Social facilitation played a role as wasdocumented in another context before translocation(Strum, 1983a). The incorporation of new foods into thediet was strongly related to specific social events. Forexample, adults in translocated troops watched and fol-lowed indigenous baboon troops. The strangers builttheir home range by tracking the path of local troopsand foraging on some of same foods. In addition, whenlocal males migrated into the translocated troops, theybrought indigenous information. The translocatedbaboons’ behavior tracked the immigrant male’s behav-ior. In this way, they learned to find water in dry sandrivers and began using several novel large succulents(Sansevieria intermedia, Sansevieria abyssinica) for bothmoisture and food.

Another value of the social group could only be called‘‘emotional support’’ (Hannah and McGrew, 1991). Thiswas evident during the accidental fission of one group atrelease and their subsequent reunion. Loud greetings,extensive embracing, and other amplifications of typicalbaboon reunion signals punctuated this meeting (Strum,2001/1987b). It was the exaggerations of these normalbehaviors that pointed to the stress of separation andthe relief of reunion.

A comparison of the baboon translocation with subse-quent primate reintroductions and translocations addforce to my conclusions. Survival skills are lost in captiv-ity. Artificially created groups fall apart (Kawai, 1960;de Vries, 1991; Vie and Richard-Hansen, 1997). Undernormal circumstances (and in extraordinary conditions),the social group provides the context for appropriatelearning and as a resource for that learning (King, 1994;Russon, 1999; Crast et al., 2010; Leca et al., 2010). Rein-troduced captive primate groups fail to meet the learn-ing challenges of their wild habitat even after extensivepre-release training (Kleiman and Rylands, 2002).

The translocation gave other insights about adaptabil-ity, chance events, and the importance of the social. Anight-time encounter with elephants was an ‘‘accident’’that changed the future of one of the translocated troops(Strum, 2001/1987b). Surrounded by elephants at theirsleeping site, Pumphouse moved 5 km during the night,an unprecedented act for baboons and other diurnal pri-mates. I know this because they marched past the lonehuman outpost in the area to reach another set of sleep-ing rocks at the edge of their home range. Subsequently,Pumphouse abandoned more than half of their rangeincluding the best rainy season portion. Following thatmove, group size declined as males and even motherswith infants left to join other, indigenous, baboon troops.Just when it seemed that Pumphouse might simply beabsorbed into the local population, the exodus stopped.New males joined and the next stage in this troop’s his-tory began.

There were subsequent home range shifts but none asprecipitous as the first. By 2000, Pumphouse ranged morethan 20 km from their release site. By contrast, Wabaya,

the previous raiders (now called Malaika trading ‘‘the badguys’’ for the ‘‘the angels’’) who were translocated to thesame location stayed put from 1984 until 2007.

All but the first home-range shift tracked a resourcegradient; however, information about and the attractionof food resources weren’t enough to force a move. Theshifts depended on social processes. Baboons are not ter-ritorial; adjacent groups have overlapping home rangeswith undefended boundaries, although intensively usedcore areas are sometimes defended. Normally, the con-servativeness of females prevents a baboon group fromcrossing home-range boundaries. Each subsequentPumphouse range shift followed an influx of immigrantmales [see Rowell’s suggestions about sex-biased knowl-edge (Rowell, 1972)]. These immigrants had firsthandexperience of the resource gradient because they camefrom there. However, even with that knowledge, onemale was ineffective. It took a cohort of four or moremales, all indicating in the same direction during troopmovement, to succeed. There was a time lag because themales had to first create friendships with females inorder to influence troop direction. Clearly, knowledgewas vital, but action relied on social processes.

Complexity 3: The social group is an organ of adap-tation; accidents of history create different socio-ecological paths

The translocation was a real test not an imaginaryone. If ever there was a situation where survival of thefittest should operate, where competition should havehad an upper hand, this was it. Instead other baboons,either from within the translocated group or the indige-nous population facilitated both learning and survival.The translocation, even more than the crop raiding,pointed out how evolutionary principles get embedded ina specific time and place and why context matters. Eachgroup’s ‘‘natural history’’ illustrated a variety of differentpaths. Chance (like an encounter with elephants), con-tingency (how many immigrant males from which area),and evolutionary principles interact to generate baboonoptions and baboon responses. The process was infinitelymore complex than explanations collapsed into evolution-ary time might suggest.

Fusion of two groups: Baboons negotiate thenature of their social group (2000–2002)

Fusion, when two groups merge to become one, is rarein baboons, so rare that it has been observed only threetimes, once in baboons in Amboseli National Park in1960s (Altmann and Altmann, 1970; Altmann et al.,1985), once among baboons in Mikumi National Park,Tanzania (Wasser et al., 2004), and once at De Hoop inSouth Africa (Henzi et al., 2000). There are only a fewother cases reported for cercopithecine monkeys despitethe hundreds of thousands of hours that cercopithecineshave been studied in the wild. These include two vervetfusions (Hauser et al., 1986; Isbell et al., 2002; Isbell,2009), one toque macaque fusion (Dittus, 1987), and sev-eral cases of fusion in Japanese macaques (Maruhashi,1992; Takahata et al., 1994; Sugiura et al., 2002).Descriptions suggest that the fusion happened almostinstantaneously (or over a short time for toque maca-ques). Two separate monkey groups come together in theevening at a shared sleeping site and leave the next dayas an integrated merged group.



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This is quite different from fission/fusion societiesamong primates where coming together and splittinginto smaller, usually foraging groups, happens on adaily or weekly basis (Aureli et al., 2008). Chimpanzees(Lehmann and Boesch, 2004) and spider monkeys(Chapman et al., 1995) are well-known examples.

I have documented four baboon fusions in just over adecade. The first fusion was 16 years after translocationand involved one of the translocated troops, Malaika (theangels, previously the bad guys) and an indigenousgroup, Soit Oitashe, that had been studied since 1985(Barton, 1993). What made this (and subsequent fusions)so distinct is that the process took more than 2 years.During that time, individuals in each group engaged inextensive negotiations about merging both within thegroup and across the groups.

The impetus for the first fusion involved several eco-logical events including the creation of a wildlife sanctu-ary on communally owned land that overlapped thebaboons’ home range. The sanctuary led to an increasein prey and predator numbers. Later, the large mammalprey species left. This made local pastoralists’ dogs andthen the baboons the prey. Predation rates rose to un-precedented levels.

Who did what and when during the fusion processdepended on specific events and on daily negotiationsinvolving particular individuals and age-sex classes. Thetranslocated troop, Malaika, was the smaller of the twotroops. Malaika shadowed the indigenous group, SoitOitashe, initially, but roles switched as Soit Oitashe, theindigenous group, lost members to heavy predation.

The sum of the forces of attraction and dispersal deter-mined how mixed the two groups might be at any onetime. For example, adult and subadult females were veryattracted to new babies in the other troop. Sexually recep-tive females also approached the other troop’s males. Sev-eral females from Malaika were drawn to a male friendwho had recently emigrated back to his natal troop, SoitOitashe. Large subadult and adult males, in both troops,herded their females away from the vicinity of the othertroop’s males trying to keep the two groups apart. Thiswas only a small part of the daily push and pull of indi-viduals, relationships, and classes of animals.

Leaving the sleeping rocks in the morning no longerfollowed a standard procedure because each group hadits own indicator animals and there was no certaintyabout who was going to follow whom. Foraging duringthe day was also problematic because Malaika’s smallerhome range was entirely contained within Soit Oitashe’slarger home range. Initially, Malaika refused to cross itsown boundaries when Soit Oitashe moved on. Instead,Malaika waited, intercepting Soit Oitashe on its wayback to the sleeping site. As the fusion progressed,Malaika did cross this invisible line, albeit hesitantly,thereby benefiting from access to new resources. Eventu-ally, the home range of the fused troop (now called Nabo,Maasai for coming together) represented a compromisebetween the two previous home ranges.

Feeding competition also played a role during thefusion process. For example, acacia flowers are a pre-ferred and high-quality food (Barton, 1993). Flowersemerge during the dry season. Their distribution is lim-ited both at the start and at the end of blooming. Duringthese times, Soit Oitashe displaced Malaika from the fewtrees that had flowers. In response, Malaika would sneakaway to feed undisturbed and out of sight. However,Malaika paid a high price for this maneuver because

when Soit Oitashe noticed, they searched for them andaggressively mobbed Malaika when they found them.

For two groups to merge, the two female hierarchiesneeded to be integrated. Initially, Malaika’s high-rankingfemales kept pushing all of Soit Oitashe’s females. Withthe support of their male friends, Malaika females man-aged to be in the middle of the integrated dominance hier-archy and forcing their way upward. However, Malaikamales stopped supporting their females. Without male sup-port, Malaika females dropped to the bottom of the inte-grated female hierarchy while maintaining their originalrankings among themselves.

Specific individuals had disproportionate impact onthe degree of mixing between the two groups. Thisincluded two Malaika females and specific males fromboth groups. Low-ranking Soit Oitashe females alsobecame the most active and gave the most aggressive re-sistance to any attempt by Malaika females to push upthe integrated female hierarchy. An illustration of theinfluence of specific baboons was the effort that one SoitOitashe male exerted to keep his troop’s females frominteracting with Malaika. The day he emigrated, therewas a noticeable increase in intertroop interactions andin spatial proximity between members of the two groups.

Given the length and extent of the process, I had todevelop criteria to use to decide when the two troops hadbecome one group. The criteria reflected what I felt wereaspects of normal group sociality. These included the ab-sence of previous troop bias in proximity, grooming andother social interactions, and troop movement negotia-tions with indicators and followers responding acrossprevious troop lines. Foraging subgroups should bemixed, and the fused group should react as an inte-grated troop in encounters with other groups, duringpredations by baboons, toward new male immigrants, toseparations and reunions, and to social disruptions. Ofcourse, the fused group had to have an integrated femaledominance hierarchy and an integrated male hierarchy.It therefore should not be a surprise that integratingtwo social systems took such a long time.

Why fuse? Why fuse now? The answers to those ques-tions offer a test of major socioecological theories ofsocialness (see above and Dittus, 1986). Some of thefusions reported in the literature took place because oneor both groups were too small to be viable in terms ofsocial and sexual interactions and predator protection.Protection against predation likely played a role in thefirst baboon fusion I documented, although the sizes ofboth troops before merging were within the normalrange for olive baboons and had all age–sex classes rep-resented. Yet before the fusion, both lost many groupmembers to predators. By contrast, after the fusion, themerged group lost none despite the continued presenceof predators in the area.

The details of negotiations suggest, however, that thebaboon reality was much more complex than simplydefense against predation. Malaika traded off feedingcompetition and protection from danger on a daily basisuntil the fusion was complete. Once fused, it bore thecost of feeding competition but benefited from enhancedpredator protection. Soit Oitashe benefited from betterprotection while remaining dominant in feeding competi-tion. The costs and benefits of fusion, therefore, were dif-ferent for Malaika and Soit Oitashe. Costs and benefitsalso diverged for different age–sex classes and even forindividual baboons. Moreover, the benefit to cost ratiochanged based on season, location, and day. This push/pull of fusion was even more elaborate than the processof fission I had documented during the crop-raiding era.



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Complexity 4: Baboons negotiate almost everything,even the nature of their social group

Baboon negotiations during the fusion were about thenature of the social group to a degree not yet docu-mented for a nonhuman primate species. The fact thatthe process took over 2 years and involved dyadic, tria-dic, and polyadic interactions in the context of every ba-sic aspect of baboon life suggests that the term ‘‘nego-tiation,’’ in its human sense, is appropriate for baboonsas well.

The negotiations were complex. The socioecology of thefusion was complex. The interaction of levels was com-plex. However, there was a ladder of complexity[building on Hinde’s model of levels (Hinde, 1976, 1987)]from dyadic interactions, cascading upward to relation-ships and subgroupings, and clusters of subgroupings totroops each with their own histories and negotiatinginterests relative to each other and to higher and lowerlevels. This was embedded in environmental complexity,which operated at different spatial and temporal scales.As ecological factors are often not correlated (e.g., theeffects of rainfall, food availability, predation, disease,and human impacts are often independent of eachother), one simple principle cannot govern what theappropriate response will be. One translocated troop,Pumphouse, reacted as if the elephant risk was greaterthan the loss of food resources. Another translocatedtroop, Malaika, accepted the cost of feeding competitionin exchange for increased safety. This does not makeselection random or arbitrary. Rather, it points out animportant constraint and obstacle: selection must oper-ate on a range of point responses to challenges that aresometimes themselves complex and independent, sug-gesting that evolutionary explanations need to incorpo-rate, rather than eliminate, complexity, chance, and con-tingency. At many times in a study troop’s history, it waspossible to identify probable evolutionary causes of ba-boon responses; however, these did not operate alone.For example, although it is tempting to conclude thatpredation pressure explained the first fusion, another in-digenous troop in the same area, Musul, lost members topredators and yet didn’t try to fuse.

My argument so far can be summarized as follows.Looking at the scale of baboon daily life, focusing on pro-cess rather than only on outcome, unearths layers of com-plexity and illustrates how complexity is generated. Out-comes are neither random nor deterministic in a way of-ten assumed when scaling up to make evolutionaryarguments. Evolutionary time speculations of cause andeffect assume rather than clarify how evolutionary princi-ples are situated by chance, contingency, and history. Thisis because they either lack the information or ignore theimportance of context and ‘‘black-box’’ the relationshipsbetween real behaviors and evolutionary outcomes.

My approach is not just a focus on proximate ratherthan ultimate explanations of behavior. The baboon datachallenge some of the fundamental assumptions abouthow behavior evolves. Tinbergen (1963) highlighted fourquestions that must be addressed in any comprehensiveexplanation of a behavior. His framework identified boththe ‘‘how’’ proximate level (mechanism and ontogeny)and the ‘‘why’’ ultimate level (function and phylogenetichistory). Yet, the ethologists, like Darwin before them,had to assume the feedback between proximate and ulti-mate levels while studying ‘‘static’’ behaviors. Equallyimportant, ethologists had to examine simplified contexts

gaining limited insights about how behaviors fit togetherinto a complex whole or how that complex whole canchange during the lifetime of the individual. The baboondata offer a dynamic and integrated view of real-life be-havioral complexity. From this vantage point, the inevi-tability of an individual’s choices and therefore the inevi-tability of the link between proximate and ultimate cau-sation seems less compelling.

PART 2: MANAGING COMPLEXITY

Managing complexity: Redefining the meaningsof social

In 1987, Bruno Latour and I proposed a differentapproach to compare human and nonhuman primate so-ciety (Strum and Latour, 1987). We were struck by theunlikely similarities between his subjects, scientists inlaboratories (see Latour and Woolgar, 1986/1979), andmine, baboons in the wild.

Baboon negotiation, even at the minor level I had docu-mented back then, raised a profound question: does soci-ety exist or is it created? At the time, we contrasted twomajor views about society. What holds society together?Traditional approaches to this question assume that soci-ety exists and actors enter society adhering to ‘‘rules anda structure that are already determined’’ (Strum andLatour, 1987, p. 785). This is the definition of an‘‘ostensive’’ society. For most descriptions of society, it cer-tainly seems that way. By contrast, in a performative so-ciety (Goffman, 1971/1959; Garfinkel, 2003/1967), individ-uals actively create and define society for themselves andfor others. Therefore society, rather than being a preex-isting structure, is actually constructed through ‘‘themany efforts to define it; it is something achieved inpractice by all actors’’ (Strum and Latour, 1987, p. 785).We argued for a shift to examine how actors create (per-form) their society. In hindsight, we were changing focusfrom outcome to process motivated by our data on nego-tiation in baboon and human social groups. Many fieldshave since embraced this shift (see below).

Although we argued that the process might be similarfor baboons and humans, it was clear that the outcomesare different. Transforming baboons into active perform-ers of their society doesn’t put them ‘‘on a par withhumans.’’ We proposed that the difference is to be foundin the practical means actors have to ‘‘enforce their ver-sion of society or to organize others on a larger scale.’’Baboons have only themselves, their bodies (includingbrains and minds), social skills, and whatever socialstrategies and relationships they can construct asresources. Some factors are embodied and change slowly;age, sex, perhaps kinship and dominance need not becontinually reconsidered. However, social skills are ‘‘softtools’’ and with them baboons can build only ‘‘soft’’ soci-eties. Other factors and contingencies must be continu-ally tracked and ‘‘performed.’’ Baboons become the arche-typical ‘‘competent member’’ of the ethnomethodologists(Garfinkel, 2003/1967) constantly subject to the interfer-ence of others who are trying to do the same thing. Theylive in a ‘‘complex’’ society.

Humans, by contrast, bring extrasomatic resources tobear in performing society. Ironically, according to thisframework, material resources, language, and symbolssimplify the task of creating society and of strengtheningthe social bond. Human society becomes a ‘‘complicated’’latticework, which looks ostensive because so much canbe held constant over space and time. These material and



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symbolic assets create a material and symbolic structurethat human actors now enter (the traditional view of soci-ety). As a result, humans accomplish two new aspects ofthe social link. They can simplify social negotiations byusing extrasomatic resources. This makes it possible tobuild a larger more complicated social structure from thecomplex baboon society. (Our terminology may be confus-ing in light of the developments of complexity science inthe last three decades and the interchangeable use of theterms ‘‘complicated’’ and ‘‘complex’’ in everyday language.However, in the 1980s, we felt the contrast embedded inour use of the two terms was appropriate and I continueto draw on that distinction. Baboons live in a complex so-ciety where many things impinge simultaneously, needingattention constantly. Humans live in a complicatedsociety which like a snowflake is built of simple unitsexpanded out to make a large complicated but not com-plex entity.) Baboons are limited in the ways they canmanage complexity because they can’t simplify much oftheir negotiation. This in turn limits the size and scale oftheir society when compared with humans.

An amusing illustration of this contrast betweenbaboons and humans can be found in ‘‘hats’’ (Fig. 1). Ifbaboons wore hats, they could simplify their social nego-tiations saving a lot of time and effort. These materialsymbols contain information about roles and expecta-tions of behavior. If only baboons had ‘‘hats,’’ they couldbegin to shift from complex society where almost every-thing impinges simultaneously and needs to be continu-ally negotiated toward a complicated society where nego-tiations are simplified, more focused, and produce morestable outcomes that can travel over space and time.

In summary, redefining the social link suggests thatbaboons and humans engage in the same process of cre-ating society but use different resources. This producesdivergent societies. Baboon society is complex becausethe ways to simplify, hold constant, black box are lim-ited. Baboon complexity often verges on the edge ofchaos as so many factors impinge simultaneously onnegotiations. The baboon evidence for complexity andnegotiation that I’ve gathered since we wrote the articlebolsters the argument. The volume and scale of negotia-tions that exist each day create the need for structurethat goes beyond kinship. Structure creates relative sta-bility and predictability, reducing what otherwise wouldbe intolerable transaction costs of living in a large andheterogeneous social group.

Recently, Shultz et al. (2011) modeled the evolution ofstable sociality in primates. Their conclusion that therewas a step-wise evolution from solitary to multi-male/multi-female groups, which only later reverted to one-male and pair-living family groups, contracts previousspeculations but fits our framework very well. One solu-tion to the complexity problem is to revert to smallerand less heterogeneous groupings. In fact, recent eventsin one baboon troop illustrate just this point. This troopappears to be simplifying social complexity through per-manent one-male subgroupings that are not ecologicalforaging units found in fission–fusion societies or in mod-ular multilevel societies like hamadrayas baboons (Swe-dell and Plummer, in press).

Managing complexity: Remodeling the femalehierarchy so that rank simplifies complexity but

is not linked to reproductive success (2001–2010)

The evidence just presented (and more that I don’thave space to review) raises the question of how baboons

deal with complexity and how much complexity they canhandle? Dunbar (1996) suggested that the transactioncosts of a typical primate grooming encounter limit thenumber of grooming partners an individual can havehence humans switch to gossip in the service of a muchlarger social network. Economics and political sciencealso see human interactions in terms of transaction costs(North, 1987; Coase, 1998; Beccevra and Gupta, 1999;Putnam, 2000; Rao, 2002). I suggest that baboons, too,have transaction costs similar to those identified forhumans: finding the information needed for a particularinteraction, the bargaining costs of reaching an agree-ment with another individual, and the policing andenforcement costs involved in monitoring and reassess-ing the relationship and the interaction. These seem ru-dimentary to any complex primate social relationshipand exchange.

Historically, those studying primates generallyassumed that social structure and social grouping exist.For example, DeVore/Washburn/Hall proposed the maledominance hierarchy as the organizing principle of thebaboon group (Washburn and DeVore, 1961; Hall andDeVore, 1965; Strum and Fedigan, 2000b). At the sametime, Chance (1967) suggested ‘‘attention’’ as the mecha-nism. The discovery of a female matrilineal hierarchy in



Fig. 1. What if baboons wore hats? (Credit: Dr. Shirley C.Strum!C ) [Color figure can be viewed in the online issue, whichis available at wileyonlinelibrary.com.]

11DARWIN’S MONKEY


rhesus macaques on Cayo Santiago (Sade, 1967) pro-vided an alternative ‘‘structure’’ for a monkey groupwhere males leave and females stay. Sociobiology laterinjected kinship and the gene calculus of inclusive fit-ness, sexual selection, and parenting strategies to createsocioecological determinants of group configurations(Williams, 1966; Trivers, 1972; Wilson, 1975). Thesestrengthened the idea that female matrilines and thefemale dominance hierarchy were evolutionary adapta-tions and the primary structure of a baboon group.

Arguments about hierarchy, female or otherwise, haveassumed that rank will be strongly correlated to repro-ductive success (Hausfater, 1975; Altmann et al., 1988;Cheney et al., 2006). Yet, data since the 1970s show aninconsistent and often poor fit between baboon femalerank and parameters of female evolutionary success.Instead, other factors appear influential like femalesociality (Silk et al., 2003, 2010b), female age-specific fe-cundity (Strum and Western, 1982), environment(Wasser et al., 2004), or a variety of factors that seem tocancel each other out (Brown and Silk, 2002; Wasser etal., 2004; Silk et al., 2005; Crockford et al., 2008; Silkand Strum, 2010).

The imperfect fit between female rank and reproduc-tive success is not surprising if attention is on whatactually happens. Then evolutionary principles operatein a context also shaped by complexity, chance, contin-gency, and history. The surprise is, instead, that there isa stable female hierarchy at all despite limited evolution-ary benefits.

I suggest that the female dominance hierarchy has adifferent purpose. Its function is primarily to create pre-dictability (and stability) so that transaction costs forfemales and others can be reduced. The complexity of ba-boon social life needs to be simplified. If the transactioncosts of grooming limit the number of grooming partners[and stress is lower when a female baboon has fewerrather than many grooming partners (Crockford et al.,2008; Wittig et al., 2008)], imagine the social transactioncosts (and stress) involved in any part of baboon dailyroutine if an animal didn’t know in advance its relation-ship to others. Individuals, and by analogy the troop,would be paralyzed by minute-to-minute negotiationsinvolved in the process of where to feed, rest, or travel,whom to approach, and whom to avoid. There would beno time for the basics of survival or enough time andenergy to meet any new challenges.

If I am correct that the female hierarchy is primarily‘‘structure,’’ then there need not be a strong correlationbetween female rank and individual reproductive successand no conundrum about why low ranking females stayin a group. All individuals benefit from predictabilityand stability no matter their rank.

However, why use the female hierarchy instead ofsome other structure to generate predictability and sta-bility? I’m not suggesting that the baboons think aboutthe problem and consciously create the solution. Instead,it is obvious that the female hierarchy is easily gener-ated from evolutionary principles such as kin selectionand reproductive value (Vx) (Williams, 1966). In baboonsand other cercopithecines, a mother’s intervention onbehalf of her younger offspring in altercations with anolder offspring creates an internal family hierarchy inwhich the youngest sibling is the highest ranking. Thenormal expansion of a family over time would fashion agroup hierarchy where only those closest in rank arelikely to be related enough for kin selection to operate

(Seyfarth, 1977). The female hierarchy thus easily fulfillsthe need for a structure to reduce transaction costs. Asbaboons practice female philopatry, this hierarchy alsoorganizes the largest cohort of animals in the group. Ofcourse, there are other evolutionarily generated struc-tures in a baboon troop including the male dominancehierarchy, male–female friendships, and other affiliativebonds (like those between play group members), but allof these are more dynamic, more ephemeral, and incor-porate fewer individuals than does the female hierarchy.

If the female hierarchy is co-opted as primary struc-ture, then it is the conservative nature of females [basedon reproductive constraints of female mammals (Trivers,1972, 1974)] that helps to keep this hierarchy relativelystable and predictable. A male baboon who loses an en-counter to another male might continue to contest theoutcome throughout the day or even the week. A femalewho loses an encounter to another female rarely disputesthe results. This contrast results from sex differences inrisks and benefits.

However, the female hierarchy isn’t invariant. I’veseen what happens when the female hierarchy is unsta-ble. This evidence supports my argument. The female hi-erarchy (in the different study troops) has changed a fewtimes during the last 40 years. These have been mostlyadjustments in rank between mothers and daughters,disruptions but not of major concern to anyone but themembers of the family. By contrast, the few majorchanges that have occurred in the overall female hierar-chy are instructive. They elicited lots of aggression someresulting in injuries. The aggression also disrupted basicdaily activities like foraging and travelling. Disorderquickly spread from a few females through the groupembroiling individuals not initially involved. Group lifecame to a standstill for a good part of several days whilethe continued instability affected individuals and thetroop for weeks and even months. It is not hard to imag-ine, from these periods of disruption, why a stable andpredictable structure is crucial not just for females butfor the rest of the troop.

The possibility exists that there may be a better fitbetween rank and individual reproductive success underspecific conditions (Cheney et al., 2004, 2006). For exam-ple, high rankers have preferred access when it is feasi-ble to monopolize key foods during a resource bottleneck(Barton, 1993). However, during the decades of my study,such situations turned out to be few, short, and did notproduce the expected fit between female rank and repro-duction (Strum and Western, 1982; Silk and Strum,2010). This was true even during critical periods such asdroughts probably because the foods left then are small,dispersed, and not defensible.

Given the complexity of baboon reality, individuals(and groups) need a way to manage daily life. It makesmore sense, in this context, to view the female domi-nance hierarchy as a transactional principle than as agenetic characteristic of individuals or as the geneticconsequences of the behavior of individuals. It is the ba-boon version of what humans do; ‘‘. . .an economizingbehavior in the sense that it greatly reduces the transac-tion costs of social interactions and permits efficient col-lective action’’ (Fukuyama, 2011). In the same way thatmanners in human societies make life livable, workable,and usually prevent descent into anarchy, the femalehierarchy creates a livable, even, civil social life forbaboons. Reproductive success would not be possibleotherwise; however, this is not the same as saying that a



12 S.C. STRUM


female’s rank in the hierarchy is somehow directlyconnected to her reproductive success.

The importance of structure is intuitively obviouswhen complexity and process are taken seriously. Thereare analogous arguments about structure from otherfields. For example, the value of structure in biologicalsystems is well summarized by Weiss and Buchanan(2009). For humans, a variety of theories argue for thebenefit of structure to reduce uncertainty, minimize cog-nitive dissonance, build social relationships, and facili-tate social exchange (for cybernetics, see Bateson, 1967;Watzlawick and Bevin, 1967; Harries-Jones, 1995). Infact, Festinger (1985/1957; Harmon-Jones and Harmon-Jones, 2007) suggested that humans seek consistencyand try to reduce dissonance in any new situation.Recent approaches to human cognition including distrib-uted cognition (Hutchins, 1995; Forster and Rodriguez,2006; Barnard, 2010) and situated action (Suchman,1987; Rogoff, 1990, 2003; Lave and Wegner, 1991) relyon a nontraditional idea of ‘‘structure’’ that is similar tomy argument. There may be indirect or downstreamimpacts of structure on female baboon reproduction, butI suggest that the value of structure is not directlyreproductive success.

Managing complexity: Extinction, tolerance,slippage, and the evolution of the good enough

(2007–2011)

An underlying assumption of evolutionary argumentsis that there are winners and losers (Weiss and Bu-chanan, 2009; Watts, 2010). Yet, in the vast span of lifeon earth, more than 99% of all species have gone extinct(Raup, 1986; Wilson, 2002; Barnosky et al., 2011). As ev-olutionary history is continuous and the end point in ev-olutionary time is most probably extinction, calculatingcosts and benefits has to be sensitive to that history.Species who flourished at one point later disappeared.This is relevant to my argument in two ways. First, aparticular point in time may or may not be representa-tive of what has happened or what will happen. I recog-nized this about the baboons I’m watching and it willapply equally to other species. The power of evolutionaryarguments will therefore depend on capturing as muchof the (natural) history as possible. Second, the adapta-tionist paradigm (Gould and Lewontin, 1979; Laland andBrown, 2011/2002) often assumes that animals in natureare finely, even perfectly tuned to their environmentand, at least until recently, that what we observe are theelements of this excellent fit. Yet, focusing on real livesin real time illustrates how difficult it is to know aboutthe consequences of particular actions or to decidewhether, for example, a baboon individual or group(since individuals don’t exist outside of groups) is mak-ing a mistake.

I had the opportunity to consider this issue during asecond fusion event. This time the impetus appeared tobe food, not predators. The little group, Musul, thathadn’t fused 7 years earlier, initiated a fusion for a dif-ferent reason, to gain access to an important new foodresource or so it seemed. This resource was dominatedat the time by other, larger, baboon groups (who werenot part of my study).

The resource they sought was the fruit of Opuntiastricta, an exotic invader which had only just appearedin Musul’s home range. Ironically, before this fusionMusul had been my ‘‘control’’ as a test of the costs and

benefits of ‘‘not fusing.’’ Musul targeted Nabo (itself theresult of the previous fusion of Malaika and SoitOitashe discussed previously). By this time, Nabo hadoperated as a well-integrated group for more than 7years. Unlike the earlier fusion, Musul didn’t shadowNabo. Instead, Musul tried to lead Nabo to the areawith the best cactus.

Initially, most of Nabo baboons resisted probablybecause the area was outside of Nabo’s traditionalhome range and already hotly contested (baboons canhear intertroop interactions beyond where they nor-mally range). As the Musul–Nabo fusion progressed,Musul females exerted more and more influence onNabo through their growing network of friendshipswith Nabo males. Occasionally, the combined groupmade it to the cactus area only to be aggressivelyexpelled by one resident baboon group in particular.Aggressive mobbing is usually a very effective tactic todisplace another group from a location. In this case,while the intruders fled from the aggression, they keptcoming back. Musul–Nabo endured repeated evictionsover more than a year but also developed evasive tac-tics. For example, the invaders would leave the sleepingsite at first light to avoid being mobbed. This early de-parture meant giving up resting and socializing timeand even some feeding time clearly a disruption of theirnormal daily routine. However, leaving early didn’talways work. Often the resident troop would trackdown the invaders and push them until they wereaway from the disputed area.

The Musul–Nabo fusion (the group was now calledNamu) violated many rules of baboon life that I haddocumented during the preceding decades. I consideredwhether it might represent a baboon ‘‘mistake’’. Thequantitative data suggested that it was. No baboon wasactually killed because of the confrontations betweengroups, but during the first 18 months of the range shift,most of Nabo’s and Musul’s babies did not survive thefirst year of life. Adult mortality also increased.Autopsies of adult females showed that previously nonfa-tal conditions had turned lethal. Nutritional analysis ofthe cactus fruits indicated that its value, and thus itsappeal, might be the energy bonus provided by such alarge package of calories [see also crop raiding (Strum,2010)]. Yet, the troop must have used up that bonus andmore evading attack. Unlike during crop raiding, bodycondition didn’t improve.

Do baboons make mistakes? Was I observing the pro-cess of extinction or at least extirpation, one death at atime? My answer is different now, 4 years later, than itwas at the start of the fusion. Currently the troops havebeen fused (becoming Namu) for several years. Namu, asinvaders, eventually created a home range in the cactusarea despite all the aggression. Although Namu is stillsubordinate to the main resident troop, they aren’tmobbed as often. Namu female reproductive parametersare steadily improving along with female physical condi-tion. Age at menarche is earlier, and interbirth intervalsare getting shorter. Namu’s overall mortality hasdeclined while survivorship is improving. I had to con-clude, against my previous assessment, that Namu’s per-sistence paid off.

The second fusion provides more evidence about thepitfalls of making evolutionary interpretations of behav-ior because these depend on history and time frame.Flexibility and adaptability are more vital than I hadimagined. It is hard to do the evolutionary calculus



13DARWIN’S MONKEY


without knowing the specific history even when popularevolutionary criteria like condition, reproduction, andsurvival are available as was evident in the Namu rangeshift. Too often, the link between the behavior and its ev-olutionary consequences passes through a black boxwhere much of the work and most of the assumptions re-side [see similar argument for the interpretation of thelink between social complexity and the evolution of cog-nition (Strum et al., 1997)].

The Musul–Nabo fusion also clarifies that evolutionaryprocesses may be more tolerant, have larger acceptabil-ity spaces (Weiss and Buchanan, 2009), and allow formore variance than most evolutionary time argumentsassume. What these baboons did for more than 4 yearswas not a perfect fit to the layers of complexity in theirlife but it seems to have been ‘‘good enough.’’ Are theyon the road to success or to extirpation? It will take timeto answer that question and require measures of successsituated in their natural history.

Since complexity generates a variety of options, it isnot surprising that individuals in a baboon troop dis-agree about what to do. These disagreements must beresolved because the group is constrained to move andact as a unit. Resolution requires negotiation. Therefore,managing the consequences of socioecological complexityis a serious daily challenge for baboons. This might bemost apparent during the special circumstances I wasable to document like the incursion of agriculture, peri-ods of heavy predation, or the appearance of a new food.However, disagreements, ‘‘behavioral’’ discussions,happen during negotiations about the more ordinaryparts of baboon life such as during troop movements,consorts, when a new infant is born, and the like.

Coming to grips with complexity

These are more than just interesting stories. They areevidence about how evolution actually works. The focuson process and history reveals the importance of complex-ity, chance, and contingency in the real lives of baboons.It also highlights the flexibility and adaptability (inresponse to complexity) that pervade baboon daily life.

Other disciplines like paleontology, ecology, genetics,and cellular biology have recently made similar argu-ments. The broad integrative approach of Weiss and Bu-chanan (2009; Weiss et al., 2011) documents the impor-tance of chance, contingency, and history (and emer-gence) in the ‘‘history of life.’’ Their EcoDevoEvoperspective advocates going from evolutionary to devel-opmental and ecological time scales [see Fig. 2.2 in Weissand Buchanan (2009, p. 12) for an instructive diagram],and illustrates why chance is ‘‘always built into concep-tion, inheritance, birth, death, and much that happensin between’’ (Weiss and Buchanan, 2009, p. 197). Contextand history, for Weiss and Buchanan, are essential tounderstanding how, for example, a gene network, cell,organism, or ecosystem gets from point a to point b.Viewing evolution at these scales suggests that there aremultiple routes to success with more tolerance and slip-page and therefore more flexibility than modern Darwin-ian interpretations often allow.

A recent example in paleontology is the work of Ven-ditti et al. (2011) on body size in mammals. They con-tend that in the evolution of mammalian body sizes,diversification did not speed up and then slow downwhen ecological niches were invaded as previouslyassumed. Instead, body size diversification took multiple

routes because ecological niches were ‘‘a constantly mov-ing target.’’ They proposed ‘‘that speciation might itselfbe the outcome of unusual single events’’ (emphasized bythe author) and that to understand so-called adaptiveradiations, it is necessary to study the multiple events ina species’ life that provide it with the opportunity toadapt, rather than studying wide and general processes’’(Venditti et al., 2011, p. 393).

Lorenzen et al. (2011) offered another example. NorthAmerican Pleistocene megafuana extinctions appearmuch more complex than previously assumed. Theiranalysis demonstrates that changes in the abundance ofmegafauna were ‘‘idiosyncratic’’ because ‘‘each species(and even continental populations within species)appeared to respond differently to the effects of climatechange, habitat redistribution, and human encroach-ment’’ (Lorenzen et al., 2011, p. 364). Surprisingly, thespecies that went extinct did not have characteristicsthat set them apart from those that survived. Thisimplies a complex and contingent process (with behav-ioral flexibility in some species) rather than a simpleand deterministic one.

A recent study on the evolution of sociality in primatesprovides another parallel. Shultz et al. (2011) modeledthe evolution of primate social grouping patterns usinggenetic and social information about 217 primate spe-cies. The conclusion contradicts previous speculationsabout the evolution of primate social groupings, whichassumed that the original groups were small and simpleand that larger more complex structures developed fromthese groupings. The analysis indicates that the initialchange in social grouping was probably caused by a shiftfrom nocturnal to diurnal activity that generated largemulti-male and multi-female groups. Smaller socialstructures are derived later in a stepwise fashion thathas some phylogenetic inertia. In this view, the evolutionof primate sociality was neither simple nor gradual andlikely involved multifaceted interactions of group size,social complexity, and cooperative sociality.

The argument for, and the value of, focusing on pro-cess and description is best illustrated by modern macro-ecology (Smith et al., 2011). Macroecologists look at com-plex interactions embedded in space and time by exam-ining multiple factors and levels including morphology,physiology, behavior, ecology, phenology, and phylogeny.Taking their cue from past natural historians and bio-geographers, macroecology uses natural history descrip-tion as a critical scientific tool. Evolutionary change,they argue, is best understood in terms of complexity,history, chance, and contingency (and emergence)whether looking at the past or trying to predict thefuture.

Even studies of modern human behavior that usuallybegin with the assumption of complexity and history aremoving further in that direction. For example, a recentstudy of the effectiveness of co-management of globalfisheries identified 19 factors (summed into eight binarymeasures and their interactions) that were vital to suc-cess (Gutierrez et al., 2011). However, history and acci-dent (not planned design) determined whether a fisheryhad any of the set of these critical features. Similarly,Black et al. (2011) explained the inadequacy of previousmodels of human migration that rely only on simpleprinciples of causation. Instead, they argued that thereare numerous drivers of migration that include social,economic, demographic, and political factors. Further-more, each driver interacts with the others as well as



14 S.C. STRUM


each being influenced by environmental change. Theresult is that they can make better predictions aboutwho migrates, when, and why than previous attempts.

Another recent example for humans is Fukuyama’swork on the origins of human political order (Fukuyama,2011). He convincingly demonstrated how similar startingconditions result in radically different outcomes and that‘‘The factors driving the development of any given politi-cal institution are multiple, complex, and often dependenton accidental or contingent events. Any causal factors oneadduces for a given development are themselves causedby prior conditions that extend backward in time in anendless regression’’ (Fukuyama, 2011, p. 23).

Of course, Complexity Theory as it has developed overthe last three decades draws some of the same conclu-sions (Waldrop, 1992; Thelen and Smith, 1994; Capra,1997; Oyama et al., 2001; Ward, 2002; Johnson, 2011/2007). Complex systems models, including complexadaptive systems and dynamical systems, have recentlybeen applied to primates using social network analysisand analysis of collective behavior (King and Sueur,2011a; Sueur and Deneubourg, 2011; Sueur et al.,2011a). Some of this work formally addresses the issuesof nonlinearity and of history, chance, and contingencyin producing specific outcomes. Most work on complexsystems still falls short of addressing the context ofbehavior in the real world. For primate social networks,for example, this should include multiple interactingcontexts that set up the starting conditions and continueto influence the operation of the system.

I began thinking about complexity in the early 1970swhen I realized that male success rested on more thanthe male dominance hierarchy. Age, residency, context,and social relationships based on collaboration and be-havioral exchange all played a role. This view of socialcomplexity was my first step in expanding out from thepowerful simplifying assumptions of the previous ba-boon models. Crop raiding (1976–1984) demonstratedthe significance of ecology and how the interaction ofsocial and ecological added to the complexity of baboonlives. The disagreement about whether to raid high-lighted the way that social negotiations influencedchoices about the basics of daily life. The translocation(1984) was both a provocative experiment and an un-precedented opportunity to see baboon adaptability inaction. The value of the social group was never asobvious as after translocation; however, I also learnedthat baboons had multiple ways to succeed and thatspecific events and accidents of history set differentgroups on unique paths.

The stone of baboon ‘‘complexity’’ that I had slowlypushed up the hill in the first decades picked up incredi-ble speed rolling down the other side in the last decade.The first fusion (1999–2001) showed the full extent ofsocial negotiation about the nature of the social group,something scientists assume to be a given fact. The 2years of negotiation embedded in specific social and eco-logical events made the fusion understandable but notpredictable based on simple evolutionary rules. The sec-ond fusion (2005–2008) certainly looked like a monumen-tal evolutionary mistake but turned out not to be. Thatfusion demonstrated the constantly changing balance ofcosts and benefits and the large list of factors that hadto be considered. It also implied that evolution was moretolerant and allowed more slippage making simple evolu-tionary calculations problematic. Finally, the changes inthe female dominance hierarchy (2008–2011) bolstered

my argument about the challenge of managing complex-ity and offered an alternative meaning for the femaledominance hierarchy.

As with all complex systems, the whole is greaterthan the sum of its parts (Johnson, 2011/2007; Mitchell,2009) even though we still lack the methodology to cap-ture behavioral emergence. However, baboon naturalhistories help. They are a resource for understandinghow complexity is generated. They show how solutionsto challenges develop. They illustrate the enormity ofthe task that baboons face in managing complexity.This type of evidence also underscores the role thatcontext, chance, and contingency play in producing spe-cific outcomes on the evolutionary stage. The baboondata also raise the possibility that there are multipleways for individuals to succeed, not just one optimalevolutionary path.

PART 3: WHY SHOULD ANTHROPOLOGISTSTODAY BE INTERESTED IN BABOONS?

Washburn and DeVore (1961, 1963) used baboons spe-cifically to frame questions about human evolution.Ironically, the intuitive power of DeVore and Washburn’smodel did a disservice to their goals as the simplifiedversion was applied to other primates and even tohumans (Strum et al., 1999; Strum and Fedigan, 2000b).Nearly four decades later, I once again suggest thatbaboons may be relevant in highlighting the challengesand solutions of early human evolution.

My first decade of baboon observations led me todeclare them ‘‘almost human’’ (Strum, 2001/1987b).Indeed, they exhibited remarkable social skills, socialstrategies, and even sexual politics (for a current defini-tion of and reservations about using the word politics,see Watts, 2010), we normally reserve for humans. How-ever, the following decades of baboon quantitative dataand detailed natural histories suggested to me why, de-spite having much in common in the process of buildingsociety, baboons and humans have diverged so much.This renders the baboon vantage point particularly use-ful both for understanding what makes us human andfor refining concepts of how evolutionary processesactually work at the level of behavior.

Summary of baboon principles of the social



1. The social group is a major organ of adaptation. Thegroup offers social resources useful in meeting newchallenges (raiding, translocation, etc.) and in solv-ing daily problems (translocation, Opuntia, etc.).Baboons illustrate how this works not just why itshould work this way.

2. Social negotiation is critical to baboon life but itquickly reaches the limits of available time andcomprehension. Baboons are also constrained bytheir inability to ‘‘hold’’ nonmaterial artifacts (rela-tionships, structure, etc.) over time and space.

3. Baboon society is restricted in scale because it hasfew means to simplify social negotiations. Therefore,baboons cannot escape social complexity to build acomplicated social structure.

4. Context and history matter to baboons. Thisincludes social actions at the individual and grouplevels.

5. Collaboration (see below), not just competition, is abuilding block of baboon society.

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Examples

Cognition in the world and in the head. Baboons illus-trate why the social and the ecological cannot be sepa-rated in real life. The greatest cognitive challenge forbaboons is probably how to navigate both simultaneously[see navigational intelligence (Strum et al., 1997)].Because the two domains cannot be separated, baboonsmay reach their cognitive limits faster than predicted byeither social or ecological hypotheses about the evolutionof primate cognition (Byrne and Whiten, 1988). By con-trast, the human ability to simplify social negotiationsand build a complicated larger scale society may reducethe cognitive demands of moment-to-moment life andeffectively segregate the social from the ecological forhumans compared to baboons.

Yet, the social is also a great baboon cognitiveresource. Several recent frameworks for human cogni-tion also seem relevant to baboons (Strum et al., 1997;Forster, 2002). Situated action and distributed cognitionextend the unit of cognition and cognitive analysisbeyond the individual. They suggested that knowledgeand cognitive processes can reside in the world (situatedin time and space and distributed between social actorsand their environment) rather than just inside the headof an individual. Hutchins (1995) argued that distributedcognition makes it possible for social actors to solveproblems (and think thoughts) that an individual could

never do alone. If Vygotsky (1978) is right, that there isa ‘‘mind in society,’’ then the social realm of baboonsbecomes a resource for problem solving. Individualbaboons, like individual humans, can later appropriatesocially created solutions. This offers a mechanism forhow plans and schemas might get into the mind of anindividual.

Although the social resources available to baboons mayameliorate some of the cognitive challenges of an inte-grated socioecology, baboons eventually reach the limits oftheir skills and abilities to manage complexity. Goingbeyond this requires additions to brain/mind and a socialworld that offers more resources for solving problems.

Competition versus collaboration versus cooperation. Re-cently, Weiss and Buchanan (2009) and Sussman andGarber (2011) have illustrated a growing shift in evolu-tionary arguments from an emphasis on competition tothe importance of cooperation in daily life. Even inbaboons, a species where males have acquired the evolu-tionary anatomy for aggression, competition is just onefactor and often not the most critical. The iconic pictureof baboon society should not be two males fighting;rather it is a big male baboon grooming his totallyrelaxed infant friend (Fig. 2). As Sussman and Garbersuggested, competition is embedded in a larger socialmatrix (Sussman and Garber, 2011).

Yet, cooperation is a controversial term when appliedto nonhuman primates. The Oxford English Dictionary



Fig. 2. The iconic male baboon: friendship and trust rather than aggressive might. A: Male grooming his yearling friend (credit:Dr. Timothy Ransom!C ). B: Male resting with yearling friend (credit: Dr. Timothy Ransom!C ). C: Male with his infant and juvenilefriends (credit: Dr. Shirley C. Strum !C ). D: Male resting with one of his female friends and her juvenile daughter (credit Dr. Shir-ley C. Strum!C ). [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

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(Dictionary, 1971) defines cooperation as ‘‘to work to-gether,’’ a meaning that originated in 1616 (p. 963)which by 1830 also meant the practice of economic coop-eration. For humans, it is used interchangeably with theterm ‘‘collaboration’’ which first appeared in 1871. Thereis no scientific consensus about the definition of the termcooperation as it applies to animals and humans(Richerson and Boyd, 2005; Kappeler and van Schaik,2006; van Schaik et al., 2006; Tomasello, 2009; Weissand Buchanan, 2009; West et al., 2010). Definitions haveranged from complex and restrictive economic criteriawith analysis based on game theory (e.g., see Noe et al.,2001), to more real-life criteria like ‘‘joint commitment toa goal’’ with ‘‘mutual support’’ and the ability to ‘‘reverseroles’’ (Tomasello and Moll, 2010), and to the broadestpossible meaning of cooperation: ‘‘components workingtogether successfully by some criterion, including that ofevolutionary viability’’ (Weiss and Buchanan, 2009, p.38). One cross-cutting claim, however, is that humancooperation is distinctly different from what other ani-mals or even other primates do.

For the purpose of situating baboons, I find it useful tothink in terms of a continuum that starts with the ‘‘ge-ometry of the selfish herd.’’ Here, individuals aggregateand cohere by simple fact of trying to get away fromsomething, for instance, a predator (Hamilton, 1971). Isuggest that what comes next is called ‘‘coordination,’’which develops as the enhanced value of group livingrequires solutions to behaving as a collective in everydaylife [see also ‘‘the collective action problem’’ (Nunn, 2000;Noe et al., 2001; Sussman and Garber, 2011)]. ‘‘Collabo-ration’’ is still further in the continuum from the selfishherd. Although cooperation and collaboration are usedinterchangeably in both the common and scientific lexi-cons, I make a distinction based on insights frombaboons. In 1973, one baboon male started to ‘‘hunt’’rather than opportunistically ‘‘collect’’ gazelle prey. Hisactions were purposeful and his intent was evident inthe sequence of his behaviors. Then other males joined,initially alerted by his return to the troop covered in dryblood. Through a set of events, the males actuallylearned that collaborating in the direction of the chasepaid dividends. Later, they practiced what they learned(Strum, 1975b). I use the term ‘‘collaboration’’ in its orig-inal meaning, to work in conjunction with others, andnot as a synonym for cooperation. Collaborating baboonsdo not have a predetermined common goal. Rather theyare a collection of individuals with similar goals; in thecase of predation, each wanted meat and realized the ef-ficacy of chasing prey one way rather than another.Finally, in this scheme, ‘‘cooperation’’ is a special type ofcollective action in which participants have a preexistingcommon purpose (see also references above). Chimpan-zee predatory hunts (Boesch and Boesch-Achermann,2000) appear a rudimentary form of primate cooperation,particularly by comparison with collaborative baboonhunting. The continuum ends with human cooperation,which entails a variety of additional aspects not found inother species (but see Wilson, 2012), although the specif-ics depend on whose definition is used.

Although competition is not as central to the baboons,I have studied, as previously assumed, neither canbaboons cooperate. That they are expert social collabora-tors is visible in their social strategies of competitionand defense, in troop movements, intertroop encounters,home-range shifts, changes in diet, as well as in intricatemulti-individual social and sexual encounters. Data from

other long-term baboon research sites also provide evi-dence of social collaboration even if the investigators donot label the behaviors that way (e.g., Palombit et al.,1997; Silk et al., 2006, 2010a; Swedell and Leigh, 2006).This means that baboons regularly engage in collectiveaction that goes beyond the coordination of individuals.However, I propose that baboons have constraints. With-out additional resources, baboons can’t move from collab-oration to cooperation just as they are limited in thetype of society they can build.

On the other hand, would baboons benefit from beingable to cooperate? The origins of cooperation in humansis often attributed to a change in lifestyle, particularlythe development of gathering and hunting and its con-comitant division of labor and necessity for sharing (Leeand DeVore, 1968; Bird, 1999; Wilson, 2012). Withoutanything in their diet that could be shared, except theinfrequent prey carcass (Strum, 1975b), baboons maynot have the necessary or sufficient conditions for theevolution of cooperation. In the end, although baboonsare great collaborators, they have neither the means northe reasons to cooperate.

Culture as an organizing principle. The performativeview of society, augmented by the frameworks of situatedaction and distributed cognition, offers a novel perspec-tive on tradition and culture among baboons. Baboonsdon’t use or make material tools in the wild but they doskillfully craft friendships. These social tools are ‘‘non-material artifacts’’ (Strum and Forster, 2001) becausemaking them requires the same cognitive achievementas making material artifacts: their shape and use isn’tintuitively obvious on the surface of the material. How-ever, here the similarity stops. Social tools, unlike mate-rial tools, have difficulty expanding across space andtime. They are ‘‘soft’’ tools and difficult to stabilize. Still,since tool use is often a criterion for culture (see Fra-gaszy and Perry, 2003), baboons do have some of the ba-sic skills (Strum and Latour, 1987).

Another criterion used to identify a primate cultural‘‘tradition’’ is that the behavior should be invariantwithin a group but variant across groups (Tomasello,1999; Rendell and Whitehead, 2001; Fragaszy and Perry,2003; Richerson and Boyd, 2005). A number of baboonbehaviors or behavioral systems may qualify. For exam-ple, a hunting tradition developed in only one group(Strum, 1975b, 1976). The raiding lifestyle, the selectionof sleeping sites after translocation, differences in dietsbetween adjacent groups in the same location, and evenvariations in aspects of the friendship configurationmight be more controversial suggestions as baboon tradi-tions. I could go further and claim that every group’sfemale dominance hierarchy is a traditional system. Af-ter all, each is unique to a group, carries forward acrossgenerations, and is relatively stable over time.

What sets baboons apart from humans, if we grantthat these are social traditions, is the next step in thecultural process: the persistence and accumulation ofinnovations (Tomasello, 1999; Richerson and Boyd,2005). I have argued that for baboons, the means of ac-quisition and transmission of a tradition depends onfrequent exposure and visible actions. Thus, the hunt-ing tradition disappeared when the innovator trans-ferred out of the troop a year later. Why? Although therate of baboon predatory behavior in Pumphouse washigh when compared with other baboon and chimpan-zee groups observed at that time, predation was still a



17DARWIN’S MONKEY


rare event in daily life. Furthermore, hunting happenedaway from the troop so that most of the animals didn’tsee or participate in the actual behavior. As a result,hunting just didn’t ‘‘stick.’’ Now contrast raiding. Theopportunities to raid were frequent and after the fis-sion, the entire raider troop, not just a few animals,raided. This frequency and visibility, I propose, wereimportant contributors to the persistence of raidingbehavior. Raiding even accumulated some modificationsas raiders learned to avoid the new anthropogenic risksand human-induced mortality declined over time(Strum, 2010).

Conversely, if culture is based, in part, on internalizedrules for behavior (D’Andrade, 1981, 1990; Byrne andRusson, 1998), the same factors that may be importantfacilitators of traditions for baboons (visibility andinvolvement) could mitigate against the need for tradi-tions. Baboons have constant access to each other associal information resources (Strum, 1983a, 2010; King,1994; King and Cowlishaw, 2007; King and Sueur,2011b; King et al., in press). They can rely on distributedcognition and situated action rather than on individuallyinternalized operating principles (Forster and Strum,1994; Strum et al., 1997; Forster, 2002; Forster andRodriguez, 2006). Recently, Roediger and McDermott(2011) made a similar suggestion for humans. Theyargued that ‘‘If one individual in a group forgets criticalinformation (about food resources or dangers, forinstance), then it is wise to get an updated memory fromanother group member’’ (Roediger and McDermott, 2011,p. 48). This perspective could help explain why the twomost ‘‘cultural’’ primates so far are chimpanzees (Whitenet al., 1999, 2007) and orangutans (van Schaik et al.,2003; Jaeggi et al., 2010). If a baboon forgets how to dosomething, it can just look around. Chimpanzees andorangutans don’t have that luxury. Chimpanzee fission–fusion society (Chapman et al., 1995; Lehmann andBoesch, 2004) and the nearly solitary existence of orang-utans (van Schaik, 1999) deprive them of each other associal resources. This should increase the value of tradi-tions and possibly of culture. By analogy, if earlyhumans lived in fission–fusion societies (Grove et al., inpress), they would face challenges of ‘‘remembering’’more like chimpanzees than like baboons.

In summary, I am proposing that baboons have a soci-ety at the limits of social complexity and that they lackthe resources needed either to manage more complexityor to simplify negotiations and build a complicated large-scale society. Baboons have sophisticated cognition thattracks social, ecological, and socioecological interactions.It is likely that they appropriate solutions to new prob-lems from the social context. If so, baboons may needless ‘‘in the head’’ because they have so much ‘‘in theworld.’’ The performative process already creates somesocial traditions (culture?); however, baboons have diffi-culty with the persistence and accumulation of innova-tions because, I suggest, for baboons this depends on fre-quent exposure and actions that are visible to everyone.Although baboons are ‘‘almost human’’ in their negotia-tion and politics, baboons can’t become human becausethey lack the ability to build a complicated society froma complex one. To do this, they would need the behaviorsthat are usually classified as hallmarks of humanness,minimally the new resources that material culture, sym-bols, language-related abilities provide, and a new sub-sistence base that both permits and requires division oflabor and sharing.

Finally, I conclude that the four decades of baboonresearch and the framework outlined above is helpful inresetting the starting point for the human experiment.It is improbable that the earliest humans were less so-phisticated or embedded in less complexity than thesebaboons. Moreover, ‘‘lowly’’ baboons also serve as a re-minder that the group is a primary organ of adaptationfor most primates, that collaboration/cooperation is likelyas crucial as competition in daily life, and that socialintelligence, social skills, and social management wereat a premium long before humans or even the greatapes.

Summary of baboon principles of evolution

1. Baboons demonstrate the value of examining processrather than just outcome and the pitfalls of uncriti-cally collapsing behavior into evolutionary time. Thisis a critical methodological move. How evolutionaryprinciples work in real time and real lives can only beidentified this way.

2. History, chance, and contingency are crucial forunderstanding baboons embedded in social, ecological,and socioecological interactions. The extensive baboonnegotiations imply that there are multiple options notjust one ‘‘best’’ evolutionary solution. In fact, thebaboons add support to the assertion that ‘‘behavioraladaptability’’ is a ubiquitous trait of life but that it isoften missed because of the existing scientific empha-sis on evolutionary time and on evolutionary out-comes (Weiss and Buchanan, 2009, p. 231).

3. Thinking in terms of contingency and (natural) historyhelps to make sense of complexity. It is also easier tounderstand complexity by looking at its unfolding, howit is generated, than by puzzling about existing com-plex structures (Weiss and Buchanan, 2009, p. 176).

Given these three principles, the baboon data that Ihave just presented don’t fit the standard view of Dar-winian natural selection (Laland and Brown, 2011/2002).Instead, they correspond to Weiss and Buchanan’s alter-native evolutionary framework. Weiss and Buchananargued that chance (action without direction that hasmajor impacts; p. 36) is one of life’s important regular-ities (p. 40), that ‘‘life is a contingent phenomenon’’ (p.35), and that adaptability in the face of ‘‘changing cir-cumstances’’ means that responses are flexible and notalways prescribed in advance (p. 37). Predictability isthe basis of life processes (p. 21), and history and contextmatter because these are the contingent conditions‘‘upon which the future is built’’ (p. 40). Weiss and Bu-chanan demonstrates how this applies at the cellular,genetic, developmental, and ecological levels (Weiss andBuchanan, 2009; Weiss et al., 2011). I suggest that italso applies to baboon behavior.

PART 4: CAPTURING AND EXPANDINGCOMPLEXITY IN THE ANTHROPOCENE

Anthropologists should be interested in baboonsbecause of what they tell us about the reality of dailylives, about the challenge of complexity, and about howevolutionary principles get embedded in contexts deter-mined by history, chance, and contingency. Baboons addevidence to the suggestion that evolutionary processescontain more tolerance, multiple solutions, larger accept-ability spaces, and the possibility that an adaptive fit



18 S.C. STRUM


will be ‘‘good enough’’ rather seamless. When thestraight line of evolutionary scale opens up to capturewhat actually happens, arguments become less reduc-tionist and less deterministic [the pentagon (Weiss andBuchanan, 2009, p. 9)].

Yet studying behavioral complexity in the wild posesmethodological challenges. How do we document com-plexity and track the impact of chance, contingency, andcontext? I see no other way than by returning to compar-ative natural history as a scientific method (Dayton,2003; Smith et al., 2011). Although the plural of anec-dote may not be data [but see recent shift in medicine(Aronson, 2003)], the plural of comparative natural his-tory certainly is. I call baboons, ‘‘Darwin’s monkey,’’ notjust because he made frequent reference to them(Darwin, 1871/2004) but because baboon lives once againargue for the value of comparative natural history, thekey method that Darwin used. Following Darwin’s lead,natural history observations should include well-docu-mented details tracked across time, space, groups, land-scapes, and species. They should be aided, when possi-ble, by quantitative data and experiment. Long-termstudies become extremely vital because only they cangenerate natural histories and the kind of insights pre-sented here.

Baboons are also useful to anthropologists for reasonsthat Darwin could not have guessed. Today, it is commonpractice to end an article about primates with a com-ment about conservation. The baboons offer a singularperspective on primate conservation because they illus-trate how the evolutionary game has changed in theAnthropocene (Steffen et al., 2007; Zalasiewicz et al.,2008), the current era of human-dominated ecosystemsand landscapes. The heart of the current biodiversity cri-sis is the presence of a super-dominant species (Western,2001), humans. People either directly or indirectly createthe current threats (Wilson, 2002; Barnosky et al., 2011).The baboon data suggest that the speed of human-induced changes and the diversity of their impacts arelikely to create more complexity and introduce an evenlarger element of chance and contingency into evolution-ary processes (as illustrated by some of the baboon natu-ral histories). Baboons are not typical primates. Theirflexibility and adaptability and their range of ecologicaland social strategies seem preadapted to new human-modified landscapes which have an acceleration of paceand fragmentation of space. This may create selectivepressures for ‘‘weedy’’ species (Richard et al., 1989); how-ever, the baboon evidence suggests that it also puts apremium on smart species [a benefit that may extend toother taxa: see trends in urban passerine birds(Maklakov et al., 2011)]. Human activity fragments ba-boon populations when it fragments space. These diver-sified but isolated conditions would select for new behav-ioral responses in baboons, perhaps even at the level ofnew traditions. Yet the baboon scenario is not all rosy.The history of the Cape baboons in South Africa(Hoffman and O’Riain, 2010, 2012; Kaplan et al., 2011)illustrates the likely future trajectory for many baboons.The current reality for Cape baboons is both genetic iso-lation and unsustainable human–wildlife conflict. If thefuture of baboons is uncertain despite their special abil-ities, the situation may be even direr for the majority ofspecies who are not as adaptable as baboons. Therefore,those interested in primate conservation will need to payspecial attention to the accelerating human–wildlife con-flict over old and new resources in the Anthropocene.

This article wouldn’t be complete without a mention ofwhat Darwin’s thought about baboons. His summary isparticularly apt: ‘‘For my own part I would as soon bedescended from that heroic little monkey, who bravedhis dreaded enemy in order to save the life of his keeper,or from that old baboon, who descending from the moun-tains, carried away in triumph his young comrade froma crowd of astonished dogs—as from a savage. . . and Ihave given the evidence to the best of my ability’’(Darwin, 1871/2004, p. 791). I don’t think Darwin wouldbe surprised by the picture of baboons that I have justpresented.

ACKNOWLEDGMENTS

I thank the editor for his generous invitation to com-ment on the important lessons from my years of baboonresearch. My insights also rest on the work done bymany other individuals associated first with the GilgilBaboon Project and later with the Uaso Ngiro BaboonProject. Since 1981, Kenyan paraethologists have beenthe mainstay of the basic data collection. I thank themall for their contributions. Finally, I thank David West-ern for his distributed cognition; Katerina Semendeferifor useful comments on the article; and Bruno Latourwho first helped me to see why complexity is so impor-tant although it took many decades to collect the evi-dence.

LITERATURE CITED

Altmann J. 1974. Observational study of behavior: samplingmethods. Behaviour 49:227–265.

Altmann SA, editor. 1967. Social communication among prima-tes. Chicago: University of Chicago Press.

Altmann SA, Altmann J. 1970. Baboon ecology: African fieldresearch. Chicago: University of Chicago Press.

Altmann J, Hausfater G, Altmann S. 1985. Demography ofAmboseli baboons 1963–1983. Am J Primatol 8:113–125.

Altmann J, Hausfater G, Altmann SA. 1988. Determinants ofreproductive success in savannah baboons, Papio cynocepha-lus. In: Clutton-Brock T, editor. Reproductive success. Chi-cago: Chicago University Press. p 403–418.

Altmann J, Muruthi P. 1988. Differences in daily life betweensemi-provisioned and wild-feeding baboons. Am J Primatol15:213–221.

Altmann J, Schoeller D, Altmann SA, Muruthi P, Sapolsky RM.1993. Body size and fatness of free-living baboons reflect foodavailability and activity levels. Am J Primatol 30:149–161.

Aronson JK. 2003. Editorial: anecdotes as evidence. Br Med J326:1346.

Aureli F, Schaffner CM, Boesch C, Bearder S, Call J, ChapmanC, Connor R, Fiore A, Dunbar R, Henzi S, Holekamp K, Korst-jens A, Layton R, Lee P, Lehmann J, Manson J, Ramos-Fer-nandez G, Strier K, van Schaik C. 2008. Fission–fusion dynam-ics: new research frameworks. Curr Anthropol 49:627–654.

Barnard A. 2010. When individiuals do not stop at the skin. In:Dunbar RIM, Gamble C, Gowlett J, editors. Social brain, dis-tributed mind. Oxford: Oxford University Press. p 249–267.

Barnosky AD, Matzke N, Tomiya S, Wogan GOU, Swartz B,Quental TB, Marshall C, McGuire JL, Lindsey EL, MaguireKC, Mersey B, Ferrer E. 2011. Has the Earth’s sixth massextinction already arrived? Nature 471:51–57.

Barton RA. 1993. Sociospatial mechanisms of feeding competi-tion in female olive baboons (Papio anubis). Anim Behav46:791–802.

Bateson G. 1967. Cybernetic explanation. Am Behav Sci 10:29–32.Beccevra M, Gupta AK. 1999. Trust within organization: inte-

grating the trust lierature with agency theory. Public Adm Q23:177–203.



19DARWIN’S MONKEY


Bird R. 1999. Cooperation and conflict: the behavioral ecology ofthe sexual division of labor. Evol Anthropol 8:65–75.

Black R, Bennett SRG, Thomas SM, Beddington JR. 2011.Migration as adaptation. Nature 478:447–449.

Boesch C, Boesch-Achermann H. 2000. The chimpanzees of theTai forest: behavioural ecology and evolution. Oxford: OxfordUniversity Press. 316 p.

Brown GR, Silk JB. 2002. Reconsidering the null hypothesis: ismaternal rank associated with birth sex ratios in primategroups. Proc Natl Acad Sci USA 99:11252–11255.

Byrne R, Whiten A, editors. 1988. Machiavellian intelligence:social expertise and the evolution of intellect in monkeys,apes, and humans. Oxford: Clarendon Press.

Byrne RW, Russon AE. 1998. Learning by imitation: a hierarchi-cal approach. Behav Brain Sci 21:667–721.

Byrne RW, Whiten A. 1989. Machiavellian intelligence: socialexpertise and the evolution of intellect in monkeys, apes andhumans. London: Clarendon Press. 413 p.

Capra F. 1997. The web of life: a new synthesis of mind andmatter. London: Harper Collins. 320 p.

Chance MRA. 1967. Attention structure as the basis of primaterank orders. Man 2:502–518.

Chapman CA, Wrangham RW, Chapman LJ. 1995. Ecologicalconstraints on group size: an analysis of spider monkey andchimpanzee subgroups. Behav Ecol Sociobiol 36:59–70.

Cheney D, Seyfarth R, Fischer J, Beehner J, Bergman T. 2004.Factors affecting reproduction and mortality among baboonsin the Okavango Delta, Botswana. Int J Primatol 25:404–428.

Cheney D, Seyfarth R, Robert M. 2007. Baboon metaphysics:the evolution of a social mind. Chicago: University of ChicagoPress. 348 p.

Cheney DL, Seyfarth RM, Fischer J, Beehner JC, Bergman TJ,Johnson SE, Kitchen DM, Palombit RA, Rendall D, Silk JB.2006. Reproduction, mortality, and female repreoductive suc-cess in chacma baboons of the Okavango Delta, Botswana. In:Swedell L, Leigh SR, editors. Reproduction and fitness inbaboons: behavioral, ecological and life history perspectives.New York: Springer. p 147–176.

Chepko-Sade BD. 1974. Division of group F at Cayo Santiago.Am J Phys Anthropol 41:472.

Chepko-Sade BD, Sade DS. 1979. Patterns of group splittingwithin matrilineal kinship groups. Behav Ecol Sociobiol 5:67–86.

Coase R. 1998. The new institutional economics. Am Econ Rev88:72–74.

Crast J, Hardy JM, Fragaszy D. 2010. Inducing traditions incaptive capuchin monkeys (Cebus apella). Anim Behav80:955–964.

Crockford C, Wittig RM, Whitten PL, Seyfarth RM, Cheney DL.2008. Social stressors and coping mechanisms in wild femalebaboons (Papio hamadryas ursinus). Horm Behav 53:254–265.

D’Andrade RG. 1981. The cultural part of cognition. Cogn Sci5:179–195.

D’Andrade RG. 1990. Some propositions about the relationsbetween culture and human cognition. In: James W, ShwederRA, Herdt G, editors. Cultural psychology: essays on human de-velopment. New York: Cambridge University Press. p 65–129.

Darwin C. 1859. On the origin of species by means of naturalselection. London: J. Murray.

Darwin C. 1871/2004. The descent of man, and selection in rela-tion to sex. London: Penguin Classics.

Dayton PK. 2003. The importance of the natural sciences to con-servation. Am Nat 162:1–13.

de Vries A. 1991. Translocation of mantled howler monkeys(Alouatta palliata) in Guanacaste, Costa Rica. Masters The-sis, University of Calgary, Alberta.

de Waal FBM, Tyack PL. 2003. Animal social complexity: intelli-gence, culture and individualized societies. Cambridge, MA:Harvard University Press. 616 p.

DeVore I, editor. 1965. Primate behavior: field studies of mon-keys and apes. New York: Holt, Rinehart and Winston. 654 p.

DeVore I, Hall KRL. 1965. Baboon ecology. In: DeVore I, editor.Primate behavior: field studies of monkeys and apes. NewYork: Holt, Rinehart and Winston. p 20–52.

Dictionary OOE. 1971. The compact edition of the Oxford Eng-lish Dictionary. Oxford English Dictionary. Oxford: OxfordUniversity Press.

Dittus WPJ. 1986. Sex differences in fitness following a grouptake over among toque macaques: testing models of social evo-lution. Behav Ecol Sociobiol 19:257–266.

Dittus WPJ. 1987. Group fusion among wild toque macaques:an extreme case of intergroup resource competition. Behav-iour 100:247–291.

Dittus WPJ. 1988. Group fission among wild toque macaques asa consequence of female resource partitioning and environ-mental stress. Anim Behav 36:1626–1645.

Dunbar RIM. 1996. Groooming, gossip and the evolution of lan-guage. Cambridge, MA: Harvard University Press. 230 p.

Dunbar RIM. 1998. The social brain hypothesis. Evol Anthropol6:178–190.

Festinger L. 1985/1957. A theory of cognitive dissonance. Stan-ford: Stanford University Press. 287 p.

Forster D. 2002. Consort turnovers as distributed cognition inolive baboons: a systems approach to mind. In: Bekoff M,Allen C, Burghardt GM, editors. The cognitive animal: empir-ical and theoretical perspectives on animal cognition. Cam-bridge, Mass.: MIT Press. p 143–151.

Forster D, Rodriguez PF. 2006. Social complexity and distrib-uted cognition in olive baboons (Papio anubis): adding systemdynamics to analysis of interaction data. Aquatic Mammals32:528–543.

Forster D, Strum SC. 1994. Sleeping near the enemy: patternsof sexual competition in baboons. Current primatology, Vol. 1:Social development, learning and behavior. Strasbourg: Uni-versity of Louis Pasteur. p 19–23.

Fragaszy DM, Perry S. 2003. The biology of traditions. Cambr-dige: Cambridge University Press. 456 p.

Fukuyama F. 2011. The origins of political order: from prehu-man times to the French Revolution. New York: Farrar,Straus and Giroux. 585 p.

Furuya Y. 1969. On the fission of troops of Japanese monkeys.II. General view of troop fission of Japanese monkeys. Prima-tes 10:47–69.

Garfinkel H. 2003/1967. Studies in ethnomethodology. Cam-bridge, UK: Polity Press. 289 p.

Goffman E. 1971/1959. The presentation of self in everyday life.New York: Doubleday. 258 p.

Goodall J. 1988/1971. In the shadow of man. Boston: HoughtonMifflin Company. 297 p.

Gould SJ, Lewontin RC. 1979. The spandrels of San Marco andthe Panglossian paradigm: a critique of the adaptationist pro-gramme. Proc R Soc Lond B 205:581–598.

Grove M, Pearce E, Dunbar RIM. 2012. Fission-fusion andthe evolution of hominin social systems. J Hum Evol 62:191–200.

Gutierrez N, Hilborn R, Defeo O. 2011. Leadership, social capi-tal and incentives promote successful fisheries. Nature470:386–389.

Hall KRL. 1968. Behaviour and ecology of the wild patas mon-keys, Erythrocebus patas, in Uganda. In: Jay P, editor. Prima-tes: studies in adaptation and variability. New York: Holt,Rinehart, and Winston. p 32–119.

Hall KRL, DeVore I. 1965. Baboon social behavior. In: DeVore I,editor. Primate behavior: field studies of monkeys and apes.New York: Holt, Rinehart and Winston. p 53–110.

Hamilton WD. 1964. The genetical evolution of social behaviour.II. J Theor Biol 7:17–52.

Hamilton WD. 1971. Geometry for the selfish herd. J Theor Biol341:295–311.

Hamilton WJ, Bulgar J. 1993. Origin and fate of a one-malesavannah baboon group formed by fissioning. Int J Primatol14:131–144.

Hannah A, McGrew WC. 1991. Rehabilitation of captive chim-panzees. In: Box H, editor. Primate responses to environmen-tal change. London: Cahpman and Hall. p 167–186.

Harmon-Jones E, Harmon-Jones C. 2007. Cognitive dissonancetheory after 50 years of development. Z Sozialpsychol 38:7–16.



20 S.C. STRUM


Harries-Jones P. 1995. A recursive vision: ecological understand-ing and Gregory Bateson. Toronto: University of TorontoPress. 358 p.

Hauser MD, Cheney DL, Seyfarth RM. 1986. Group extinction andfusion in free ranging vervet monkeys. Am J Primatol 11:63–77.

Hausfater G. 1975. Dominance and reproduction in baboons(Papio cynocephalus). Basel: S. Karger. 150 p.

Hausfater G, Altmann J, Altmann SA. 1982. Long-term consis-tency of dominance relationships among female baboons. Sci-ence 217:752–755.

Henrich J, Boyd R, Bowles S, Camerer C, Fehr E, Gintis H.2009. Foundations of human sociality: economic experimentsand ethnographic evidence from fifteen small-scale socieites.Oxford: Oxford University Press. 451 p.

Henzi SP, Barrett L, Weingrill A, Dixon P, Hill RA. 2000. Ruthsamid the alien corn: males and the translocation of femaleChacma baboons. S Afr J Sci 96:1–2.

Henzi SP, Lycett JE, Piper SE. 1997. Fission and troop size inmountain baboon populations. Anim Behav 53:525–535.

Hinde RA. 1976. Interactions, relationships and social structure.Man 11:1–17.

Hinde RA. 1987. Individuals, relationships and culture: linksbetween ethology and the social sciences. Cambridge: Cam-bridge University Press. 207 p.

Hoffman T, O’Riain, MJ. 2010. The spatial ecology of chacmababoons (Papio ursinus) in a human modified environment.Int J Primatol 32:308–328.

Hoffman T, O’Riain, MJ. 2012. Landscape requirements of a pri-mate population in a human-dominated environment. FrontZool 9:1–23.

Holmes JG, Rempel JK. 1989. Trust in close relationships. RevPers Soc Psychol 10:187–220.

Homans GC. 1958. Social behavior as exchange. Am J Sociol63:597–606.

Hutchins E. 1995. Cognition in the wild. Cambridge, MA: MITPress.

Isbell LA. 1994. Predation on primates: ecological patterns andevolutionary consequences. Evol Anthropol 3:61–71.

Isbell LA. 2009. Demography and life histories of sympatricpatas monkeys, Erythrocebus patas, and vervets, Cercopithe-cus aethiops, in Laikipia, Kenya. Int J Primatol 30:103–124.

Isbell LA, Cheney DL, Seyfarth RM. 2002. Group fusions andminimum group sizes in vervet monkeys (Cercopithecusaethiops). Am J Primatol 25:57–65.

Isbell LA, Young TP. 2002. Ecological models of female socialrelationships in primates: similarities, disparities and somedirections for future clarity. Behaviour 139:177–202.

Jaeggi AV, Dunkel IP, van Noordwijk MA, Wich SA, Sura AAI,Van Schaik CP. 2010. Social learning of diet and foragingskills by wild immature Bornean orangutans: implications forculture. Am J Primatol 72:62–71.

Jay P, editor. 1968. Primates: studies in adaptation and vari-ability. New York: Holt, Rinehart, and Winston.

Johnson NF. 2011/2007. Simply complexity. Oxford: OneworldPublications.

Kano T. 1992. The last ape: pygmy chimpanzee behavior andecology. Stanford, CA: Stanford University Press. 248 p.

Kaplan BS, O’Riain, MJ, van Eeden R, King A. 2011. A low-costmanipulation of food resources reduces spatial overlapbetween baboons (Papio ursinus) and humans in conflict. IntJ Primatol 32:1397–1412.

Kappeler PM, van Schaik CP, editors. 2006. Cooperation in pri-mates and humans: mechanisms and evolution. New York:Springer-Verlag. 347 p.

Kawai MA. 1960. A field experiment on the process of group for-mation in the Japanese monkey (Macaca fuscata), and thereleasing of the group at Ohirayama. Primates 2:181–255.

Kawamoto Y. 2010. Modes of differentiation in Japanese maca-ques: perspectives from population genetics. In: Nakagawa N,Nakamichi M, Sugiura H, editors. The Japanese macaques.Japan: Springer. p 53–76.

King AJ, Cowlishaw G. 2007. When to use social information:the advantage of large group size in individual decision mak-ing. Biol Lett 3:137–139.

King AJ, Sueur C. 2011a. Group coodination and collective deci-sion making by primates: special issue. Int J Primatol326:1245–1442.

King AJ, Sueur C. 2011b. Where next? Group coordination andcollective decision making by primates. Int J Primatol32:1245–1267.

King AJ, Sueur C, Huchard E, Cowlishaw G. 2011. A rule-of-thumb based on social affiliation explalins collective move-ments in desert baboons. Anim Behav 82:1336–1337.

King B. 1994. The information continnum: evolution of social in-formation transfer in monkeys, apes and hominids. Sante Fe:School of American Research.

Kleiman DG, Rylands AB, editors. 2002. Lion tamarins: biologyand conservation. Washington, DC: Smithsonian InstitutionPress. 422 p.

Kuester J, Paul A. 1997. Group fission in Barbary macaques(Macaca sylvanus) at Affenberg Salem. Int J Primatol 18:941–966.

Laland KN, Brown GR. 2011/2002. Sense and nonsense: evolu-tionary perspectives on human behaviour. New York: OxfordUniversity Press. 270 p.

Latour B, Woolgar S. 1986/1979. Laboratory life: the social con-struction of scientific factors. Princeton, NJ: Princeton Uni-versity Press.

Lave J, Wegner E. 1991. Situated learning: legitimate peripheralparticipation. Cambridge, UK: Cambridge University Press.

Leca JB, Gunst N, Huffman MA. 2010. Indirect social influencein the maintenance of the stone handling tradition in Japa-nese macaques (Macaca fuscata). Anim Behav 79:117–126.

Lee R, DeVore I. 1968. Man the hunter. Chicago: Aldine-Atherton.

Lehmann J, Boesch C. 2004. To fission or to fusion: effects ofcommunity size on wild chimpanzee (Pan troglodytes) socialorganization. Behav Ecol Sociobiol 56:207–216.

Leigh EGJ. 2010. The group selection controversy. J Evol Biol23:6–19.

Lorenz K. 1950. The comparative method in studying innatebehavior patterns. Symp Soc Exp Biol 4:221–268.

Lorenzen ED, Nogues-Bravo D, Orland L, et al. 2011. Species-specific responses of late quaternary megafauna to climateand humans. Nature 479:359–364.

Maklakov AA, Immler S, Gonzalez-Voyer A, Ronn J, Kolm N.2011. Brains and the city: big-brained passerine birds succeedin urban environments. Biol Lett 7:730–732.

Maruhashi T. 1992. Fission, takeover and extinction of a troopof Japanese monkeys (Macaca fuscata yuakui) on YakushimaIsland, Japan. In: Itoigawa N, Sugiuama Y, Sackett GP,Thompson RKR, editors. Topics in primatology. Tokyo: Univer-sity of Tokyo Press. p 47–56.

Misztal BA. 1996. Trust in modern societies: the search for thebases of social order. Cambridge, Mass.: MIT Press.

Misztal BA. 2001. Normality and trust in Goffman’s theory ofinteraction order. Sociol Theory 19:312–324.

Mitchell M. 2009. Complexity: a guided tour. Oxford: OxfordUniversity Press. p 349.

Muruthi P, Altmann J, Altmann SA. 1991. Resource base, parityand reproductive condition affect female feeding time and nu-trient intake within and between groups of a baboon popula-tion. Oecologia 87:467–472.

Nash LT. 1976. Troop fission in free-ranging baboons in theGombe Stream National Park, Tanzania. Am J Phys Anthro-pol 44:63–78.

Noe R, van Hoof JARAM, Hammerstein P, editors. 2001.Economics in nature: social dilemmas, mate choice andbiological markets. New York: Cambridge University Press.276 p.

North DC. 1987. Institutions, transaction costs and economicgrowth. Econ Inq 25:419–428.

Nowak MA, Tarnita CE, Wilson EO. 2010. The evolution ofeusociality. Nature 466:1057–1062.

Nunn CL. 2000. Collective benefits, free-riders, and male extra-group conflict. In: Kappeler PM, editor. Primate males: causesand consequences of variation in group composition. Cam-bridge: Cambridge University Press. p 192–204.



21DARWIN’S MONKEY


Okamoto K, Matsumura S. 2001. Group fission in Moor maca-ques (Macaca maurus). Int J Primatol 22:481–493.

Oyama S, Griffiths PE, Gray RD, editors. 2001. Cycles of con-tingency: develpmental systems and evolution. Cambridge,MA: MIT Press.

Palombit RA, Seyfarth RM, Cheney DL. 1997. The adaptivevalue of ‘friendships’ to female baboons: experimental andobservational evidence. Anim Behav 54:599–614.

Pearce WB, Hans-Werner S. 2008. Making social worlds: a com-munication perspective. Madden, MA: Blackwell. 272 p.

Putnam RD. 2000. Bowling alone: the collapse and revival ofAmerican community. New York: Simon and Schuster Paper-backs. 541 p.

Raiffa H. 2003/1982. The art and science of negotiation. Cam-bridge, MA: Harvard University Press. 375 p.

Ransom TW. 1981. Beach troop of the Gombe. Lewisburg: Buc-nell University Press. 319 p.

Rao PK. 2002. The economics of transaction costs: theory, meth-ods and applications. New York: Palgrave Macmillan. 216 p.

Raup D. 1986. Biological extinction in earth history. Science231:1528–1533.

Rendell L, Whitehead H. 2001. Culture in whales and dophins.Behav Brain Sci 24:309–382.

Richard AF, Goldstein SJ, Dewar RE. 1989. Weed macaques:the evolutionary implications of macaque feeding ecology. IntJ Primatol 10:569–594.

Richerson PJ, Boyd R. 2005. Not by genes alone: how culturetransformed human evolution. Chicago: University of ChicagoPress. 332 p.

Roediger HLI, McDermott KB. 2011. Remember when? Science333:47–48.

Rogoff B. 1990. Apprenticeship in thinking: cognitive develop-ment in social context. New York: Oxford University Press.

Rogoff B. 2003. The cultural nature of human development.New York: Oxford University Press.

Rousseau DM, Sitkin SB, Camerer C. 1998. Not so different afterall: a cross-discipline view of trust. Acad Manage Rev 23:393–404.

Rowell T. 1966. Forest living baboons in Uganda. J Zool149:344–364.

Rowell T. 1972. The social behavior of monkeys. Middlesex: Pen-guin Books.

Russon AE. 1999. Orangutans: wizards of the rainforest. To-ronto: Key Porter Books.

Sade DS. 1967. Determinants of dominance in a group of free-ranging rhesus monkeys. In: Altmann SA, editor. Social com-munication among primates. Chicago: University of ChicagoPress. p 99–114.

Sade DS. 1972. A longitudinal study of social relations of rhesusmonkeys. In: Tuttle RH, editor. Function and evolutionarybiology of primates. Chicago: Aldine-Atherton.

Seyfarth RM. 1977. A model of social grooming among adultfemale monkeys. J Theor Biol 65:671–698.

Shultz S, Opie C, Atkinson QD. 2011. Stepwise evolution of sta-ble society in primates. Nature 479:219–222.

Silk J, Beehner J, Bergman T, Crockford C, Engh A, MoscoviceL, Wittig R, Seyfarth R, Cheney D. 2010a. Female chacmababoons form strong, equitable, and enduring social bonds.Behav Ecol Sociobiol 64:1733–1747.

Silk JB, Alberts SC, Altmann J. 2003. Social bonds offemale baboons enhance infant survival. Science 302:1231–1234.

Silk JB, Alberts SC, Altmann J. 2006. Social relationshipsamong adult female baboons (Papio cynocephalus). II. Varia-tion in the quality and stability of social bonds. Behav EcolSociobiol 61:197–204.

Silk JB, Beehner JC, Bergman TJ, Crockford C, Engh AL, Mos-covice LR, Wittig RM, Seyfarth RM, Cheney DL. 2010b.Strong and consistent social bonds enhance the longevity offemale baboons. Curr Biol 20:1–3.

Silk JB, Strum SC. 2010. Maternal condition does not influence birthsex ratios in anubis baboons (Papio anubis). PLoS One 5:e12750.DOI: 10.1371/journal.pone.0012750

Silk JB, Willoughby E, Brown GR. 2005. Maternal rank andlocal resources competition do not predict birth sex ratios inwild baboons. Proc R Soc Lond B 272:569–574.

Smith F, Gittleman JL, Brown JH, editors. 2011. Foundations ofmacroecology. Chicago: University of Chicago Press.

Smuts B. 1985. Sex and friendship in baboons. New York:Aldine. 303 p.

Steffen W, Crutzen PJ, McNeil JR. 2007. The Anthropocene: arehumans now overwhelming the great forces of nature? Ambio36:614–621.

Stoltz LP. 1972. The size, composition and fissioning in baboontroops (Papio ursinus Kerr ‘72). Zool Africana 7:367–378.

Strum S. 2010. The development of primate raiding: implica-tions for management and conservation. Int J Primatol31:133–156.

Strum SC. 1975a. Primate predation: interim report on the de-velopment of a tradition in a troop of live baboons. Science187:755–757.

Strum SC. 1975b. Primate predation: interim report on the de-velopment of a tradition in a troop of olive baboons. Science187:755–757.

Strum SC. 1976. Primate predation and bioenergetics: a reply.Science 191:314–317.

Strum SC. 1978. Dominance hierarchy and social organization:strong or weak inference. In: Presented at the Wenner GrenConference, Baboon Field Research, Myths and Models, June1978, New York.

Strum SC. 1982. Agonistic dominance in male baboons: an alter-native view. Int J Primatol 3:175–202.

Strum SC. 1983a. Baboon cues for eating meat. J Hum Evol12:327–336.

Strum SC. 1983b. Use of females by male olive baboons. Am JPrimatol 5:93–109.

Strum SC. 1983c. Why males use infants. In: Taub D, editor.Primate paternalism. New York: Van Nostrand Reinhold. p146–185.

Strum SC. 1991. Weight and age in wild olive baboons. Am JPrimatol 25:219–237.

Strum SC. 2001/1987a. Almost human: a journey into the worldof baboons. Chicago: University of Chicago Press. 308 p.

Strum SC. 2001/1987b. Almost human: a journey into the worldof baboons. Chicago: University of Chicago Press.

Strum SC. 2002. Translocation of three wild troops of baboonsin Kenya. Reintroduction News 21:12–15.

Strum SC. 2005. Measuring success in primate translocation: ababoon case study. Am J Primatol 65:117–140.

Strum SC. 2008. Commentary on de Waal primates and philoso-phers. Curr Anthropol 49:701–702.

Strum SC, Fedigan LM. 2000a. Changing views of primate society:a situated North American perspective. In: Strum SC, FediganLM, editors. Primate encounters: models of science, gender andsociety. Chicago: University of Chicago Press. p 3–49.

Strum SC, Fedigan LM. 2000b. Changing views of primate society:a situated North American perspective. In: Strum SC, FediganLM, editors. Primate encounter: models of science, gender andsociety. Chicago: University of Chicago Press. p 3–49.

Strum SC, Forster D. 2001. Nonmaterial artifacts: a distributedapproach to mind. In: Nowell A, editor. In the mind’s eye:multidisciplinary approaches to the evolution of human cogni-tion. Ann Arbor, MI: International Monographs in Prehistory.p 63–82.

Strum SC, Forster D, Hutchins E. 1997. Why Machiavellianintelligence may not be Machiavellian. In: Whiten A, ByrneR, editors. Machiavellian intelligence II: extensions andevaluations. Cambridge, UK: Cambridge University Press.p 50–85.

Strum SC, Latour B. 1987. Redefining the social link: frombaboons to humans. Soc Sci Inf 26:783–802.

Strum SC, Lindburg DG, Hamburg D, editors. 1999. The newphysical anthropology: science, humanism and critical reflec-tion. Upper Saddle River, NJ: Prentice-Hall. 285 p.

Strum SC, Southwick CH. 1987. Translocation of primates. In:Benirschke K, editor. Primates: the road to self-sustainingpopulations. New York: Springer-Verlag. p 949–958.

Strum SC, Western JD. 1982. Variations in fecundity with ageand environment in a baboon population. Am J Phys Anthro-pol 3:61–76.



22 S.C. STRUM


Suchman L. 1987. Plans and situated actions: the problem ofhuman–machine communication. New York: Cambridge Uni-versity Press.

Sueur C, Deneubourg J-L. 2011. Self-organization in primates:understanding the rules underlying collective movements. IntJ Primatol 32:1413–1432.

Sueur C, Jacobs A, Amblard F, Petit O, King AJ. 2011a. Howcan social network analysis improve the study of primatebehavior? Am J Primatol 73:703–719.

Sueur C, King AJ, Conradt L, Kerth G, Lusseau D, Mettke-Hof-mann C, Schaffner CM, Williams L, Zinner D, Aureli F.2011b. Collective decision-making and fission-fusion dynam-ics: a conceptual framework. Oikos 120:1608–1617.

Sugiura H, Agetsuma N, Suzuki S. 2002. Troop extinction andfemale fusion in wild Japanese macaques in Yakushima. Int JPrimatol 23:69–84.

Sussman RW, Garber PA. 2011. Cooperation, collective action,and competition in primate social interactions. In: CampbellC, Fuentes A, MacKinnon KC, Bearder SK, Stumpf RM, edi-tors. Primates in perspective, 2nd ed. New York: Oxford Uni-versity Press. p 587–599.

Swedell L, Leigh SR, editors. 2006. Reproduction and fitness inbaboons. New York: Springer. 322 p.

Swedell L, Plummer T. 2012. A Papionin multilevel society as amodel for Hominin social evolution. Int J PrimatolDOI 10.1007/s10764-012-9600-9.

Takahata Y, Suzuki S, Okayasu N, Hill D. 1994. Troop extinc-tion and fusion in wild Japanese macaques of YakushimaIsland, Japan. Am J Primatol 33:317–322.

Thelen E, Smith LB. 1994. A dynamic systems approach to thedevelopment of cognition and action. Cambridge, MA: MITPress.

Tinbergen N. 1942. An objectivist study of the innate behaviourof animals. Bibiotheca Biotheoretica 1:39–98.

Tinbergen N. 1963. On aims and methods of ethology. Z Tierpsy-chol 20:410–433.

Tinbergen N. 1974/1951. The study of instinct. New York:Oxford University Press. 228 p.

Tomasello M. 1999. The cultural origins of human cognition.Cambridge, MA: Harvard University Press.

Tomasello M. 2009. Why we cooperate. Cambridge, MA: MITPress.

Tomasello M, Moll H. 2010. The gap is social: human shared inten-tionality and culture. In: Kappeler PM, Silk JB, editors. Mindthe gap. Heidelberg, Germany: Springer-Verlag. p 331–349.

Trivers RL. 1972. Parental investment and sexual selection. In:Campbell B, editor. Sexual selection and the descent of man:1871–1971. Chicago: Aldine. p 136–179.

Trivers RL. 1974. Parent-offspring conflict. Am Zool 14:249–264.Van Horn R, Buchan J, Altmann J, Alberts S. 2007. Divided

destinies: group choice by female savannah baboons duringsocial group fission. Behav Ecol Sociobiol 61:1823–1837.

van Schaik CP. 1983. Why are diurnal primates living ingroups? Behaviour 87:120–144.

van Schaik CP. 1999. The socioecology of fission–fusion socialityin orangutans. Primates 40:73–90.

van Schaik CP, Ancrenaz M, Borgen G, Galdikas B, Knott CD,Singleton I, Suzuki A, Utami SS, Merrill M. 2003. Orangutancultures and the evolution of material culture. Science299:102–105.

van Schaik CP, Kappeler, Peter M. 2006. Cooperation in prima-tes and humans: closing the gap. In: Kappeler PM, vanSchaik CP, editor. Cooperation in primates and humans. Ber-lin: Springer-Verlag. p 3–21.

Venditti C, Meade A, Pagel M. 2011. Multiple routes to mamma-lian diversity. Nature 479:393–396.

Vie J, Richard-Hansen C. 1997. Primate translocation in FrenchGuiana: a preliminary report. Neotropical Primates 5:1–3.

Vygotsky LS. 1978. Mind in society: the development of higherpsychological processes. Cambridge, MA: Harvard UniversityPress. 159 p.

Waldrop MM. 1992. Complexity: the emerging science at theedge of order and chaos. New York: Touchstone/Simon andSchuster. 380 p.

Ward LM. 2002. Dynamical cognitive science. Cambridge, MA:MIT Press.

Washburn SL, DeVore I. 1961. Social behavior of baboons andearly man. In: Washburn SL, editor. The social life of earlyman. New York: Wenner-Gren Foundation for AnthropologicalResearch. p 91–105.

Washburn SL, DeVore I. 1963. Baboon ecology and human evo-lution. In: Howell FC, Bourliere G, editors. African ecologyand human evolution. New York: Wenner-Gren Foundationfor Anthropological Research. p 335–367.

Wasser SK, Norton GW, Kleindorfer S, Rhine RJ. 2004. Popula-tion trend alters the effect of maternal dominance rank onlifetime reproductive success in yellow baboons (Papio cynoce-phalus). Behav Ecol Sociobiol 56:338–345.

Watts DP. 2010. Dominance, power, and politics in nonhumanand human primates. In: Kappeler PM, editor. Mind the gap:tracing the origins of human universals. Heidelberg, Ger-many: Springer-Verlag. p 109–138.

Watzlawick P, Bevin J. 1967. Some formal aspects of communi-cation. Am Behav Sci 10:4–8.

Weiss KM, Buchanan AV. 2009. The mermaid’s tale: four billionyears of cooperation in the making of living things. Cam-bridge, MA: Harvard University Press. 305 p.

Weiss KM, Buchanan AV, Lambert BW. 2011. The Red Queenand Her King: cooperation at all levels of life. Ybk PhysAnthropol 54:3–18.

West R, Turner LH. 2009. Introducing communication theory.New York: McGraw Hill.

West SA, Mouden CE, Gardner A. 2010. Sixteen common mis-conceptions about the evolution of cooperation in humans.Evol Hum Behav 32:231–262.

Western D. 2001. Human modified ecosystems and future evolu-tion. Proc Natl Acad Sci USA 98:5465–5488.

Western JD, Strum SC. 1983. Sex, kinship and the evolution ofsocial manipulation. Ethol Sociobiol 4:19–28.

Whiten A. 2000. Social complexity and social intelligence. In:Bock GR, Goode JA, Webb K, editors. The nature of intelli-gence. Chichester, UK: Wiley. p 185–201.

Whiten A, Byrne RW. 1997. Machiavellian intelligence II: exten-tions and evaluations. Cambridge: Cambridge UniversityPress. 410 p.

Whiten A, Goodall J, McGrew WC, Nishida T, Reynolds V,Sugiyama Y, Tutin CEG, Wrangham RW, Boesch C. 1999. Cul-ture in chimpanzees. Nature 399:682–685.

Whiten A, Spiteri A, Horner V, Bonnie KE, Lambeth SP, ShapiroSJ, de Waal FBM. 2007. Transmission of multiple traditionswithin and between chimpanzee groups. Curr Biol 17:1038–1043.

Williams GC. 1966. Natural selection, the costs of reproductionand a refinements of Lack’s principle. Am Nat 100:687–690.

Wilson EO. 1975. Sociobiology: the new synthesis. Cambridge,MA: Harvard University Press.

Wilson EO. 2002. The future of life. New York: Knopf.Wilson EO. 2012. The social conquest of earth. New York: Liver-

light Publishing.Wittig RM, Crockford C, Lehmann J, Whitten PL, Seyfarth RM,

Cheney DL. 2008. Focused grooming networks and stress alle-viation in wild female baboons. Horm Behav 54:170–177.

Wrangham RW. 1980. An ecological model of female-bonded pri-mate groups. Behaviour 75:335–369.

Zalasiewicz J, Williams M, Smith A, Barry T, Coe A, Bown P,Brenchley P, Cantrill D, Gale A, Gibbard P, Gregory F, Houn-slow M, Kerr A, Pearson P, Know R, Powell J, Waters C, Mar-shall J, Oates M, Rawson P, Stone P. 2008. Are we now livingin the Anthropocene? GSA Today 18:1–8.

Zihlman AL, Cronin JE, Cramer DL, Sarich VM. 1978. Pygmychimpanzee as a possible prototype for the common ancestorof humans, chimpanzees and gorillas. Nature 275:744–746.

Zinner D, Groenveld LR, Keller C, Roos C. 2009. Mitochondrialphylogeography of baboons (Papio spp)—indication for intro-gressive hybridization. BMC Evol Biol 9:83.

Zuckerman S. 1932. The social life of monkeys and apes. Lon-don: Toutledge and Kegan Paul.

Zuckerman S. 1933. Functional affinities of man, monkeys, andapes. London: Routledge and Kegan Paul.



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