human nature 32 - question of animal culture

8/9/2019 Human Nature 32 - Question of Animal Culture

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THE QUESTION OF ANIM AL CULTURE

B en ne tt G . G ale f, J r.

McMaster University

In this paper I consider w hether traditional behaviors of anim als, like

traditions of hum ans, are transm itted by im itation learning. Review of

the literature on problem solving by captive primates, and detailed

consideration of tw o w idely cited instances of purported learning by

i mi ta ti on a nd o f c ult ure in fre e-l iv in g p rim at es (s we et-p ot at o w as hin g b y

Ja pane se m ac aqu es a nd term ite fish ing b y chim panz ee s), sugg ests tha t

nonhum an prim ates do not learn to solve problem s by im itation. It m ay,

there fore , be m isle ading to trea t anim al tra ditions an d h um an cu ltu re as

hom ologous (rather than analogous) and to refer to anim al traditions as

cultural.

K EY WO RD S: A ni ma l t ra di ti on ; A nim al c ult ure ; Im it ati on a nd le arn in g;

K oshim a Island (Ja pa n); G om be N ationa l P ark

(T an za ni a); N on hu ma n p rim at es

Im it at io n i s n a tu ra l to m an fro m c hi ld ho od ,

one of his advantages over the lower ani-

m als b ein g this, th at he is the m ost im itative

creature in the w orld, and learns at first by

imitation. (Aristo tle 1941:4486)

R ec eiv ed A ug ust 2 8, 1 99 1; a cc ep te d O cto be r 2 8, 1 99 1.

A d dre ss a ll c o r re sp o nd e nc e t o B e nn e tt G G a le f. J r. , D e p ar tm e n t o f P sy ch o lo gy , M c M as te r U n iv er -

s it y , H am i l t o n, O n ta rio

L85 4Kl,

C a n a d a .

Co py rig ht 10 1 99 2 by W alter de G ru yter, In c. N ew Y ork

Human Nature, Vol. 3, No.2, pp,

157-178.

1045-6767/92/$1.00

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T he Que sti on o f A nim al C ult ur e

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It h as b ec om e in cre asin gly fa shio nab le d urin g th e p ast d eca de fo r sc ie n-

tists to se e ev ide nce of h um an lik e m en ta l pro ce sses in a nim als a s d ive rse

as chickens and chim panzees. The possibility that anim als m ay be con-

sc io us, d ec eitfu l, se lf-a wa re , M ac hia vellian , e tc ., is u nde r serio us c on-

s id er atio n. C on se qu en tly , u se b y s cie ntists o f v oc ab ula ry tr ad itio na lly

used to describe hum an activities to describe the behavior of anim als is

probably m ore frequent today than at any tim e since the latter part of the

nin ete enth c en tu ry , w he n G eorg e R om an es, D arw in's p ro te ge a nd in te l-

lectual heir in m atters behavioral, w rote at length of sim ilarities in the

p sy ch olo gic al p ro ce sse s u nd erly in g th e b eh av io r o f a nim als a nd h um an -

k ind (R om ane s 1 88 2, 18 84).

Is it re ason able , in ligh t o f c urre nt k no wle dge , to d iscu ss th e p olitics o f

c him pan zee s (de W aa I1 98 2), th e d ece its of c hick ens (G yge r a nd M arler

19 88) o r th e feig nin g of in jury a nd d ea th b y p ip in g plo vers an d h og -n ose

snakes (B urghardt 1991; R istau 1991)? Q uite honestly, I don't know .

N either, I think, does anyone else.

Some feel (and I confess that this is my ow n bias) that it is probably

be st for scie ntists to b e c onse rva tive , to a dop t th e sim plest d esc riptio ns

and explanations of behavioral phenom ena consistent w ith available

e vid enc e (M org an 1 89 4; W illia ms 1 966 ). O th ers h av e a rgu ed c og ently

th at th e g oa l o f b eh avio ral stu die s is to d esc ribe a nd e xpla in b eh avio r as

correctly, not as sim ply, as possible. W e should, in W ilson's (1975:30)

w ords, enum erate all possible explanations, improbable as well as

likely, and then devise tests to elim inate som e of them .

F or th e b eh av iora l scie ntist, the p ro ble m p ose d b y W ilso n's pro gra m

of hypothesis generation and subsequent testing (consistent though it

m ay be w ith the view s of H em pel, P opper, and P latt) is that elim inating

e xp la na tion s, e ven the m ore u nlik ely a mo ng th em , ta ke s m ore tim e th an

m ig ht b e a ntic ipa ted . D urin g th e d ec ad es w hen te stin g an d e lim in atio n

o f a lte rna tive hy poth ese s is u nde rw ay , a q uestion re ma in s a s to w he th er

it is useful to describe or explain behavior in term s of hypothesized

processes for which little or no evidence has yet been developed. Per-

haps, as the m ore conservative insist, explanation and description

should be restricted to processes that have passed rigorous tests, that

h av e b ee n r ep ea te dly d em on str ate d.

On the other hand, during the past half century, the traditional,

conservative approach to analysis of animal behavior led research in

ex pe rim en ta l a nim al p syc holo gy do wn pa ths of stea dily d ec rea sing in -

terest to the rest of the comm unity of life scientists. C learly, it is not

a lw ay s th e ca se th at the c on se rv ativ e a ppro ac h to de scrip tio n o f a nim al

behavior is the most heuristic one (much as I m ight like it to be).

T he question of w hether anim als exhibit culture is part of this w ider

d eb ate reg ard in g the re la tio nsh ip be tw ee n h um an a nd a nim al b eha vior

and the appropriate w ay to discuss the com plex behaviors of anim als.

P RO BL EM S O F D EF IN IT IO N

L um pe rs a nd S plitte rs

D isag ree men t c on cern ing u se o f th e term

culture

to d esc rib e th e p ro d-

uc ts o f so cia l lea rnin g by a nim als is as g re at as is d isa gre em en t c onc ern-

ing the proper labels to use to describe other hum anlike behavioral

p he nom ena in a nim als. S ah lins (1 976 :1 3), fo r e xa mp le , v ie ws c ultu re a s

an em ergent property of only the m ost com plex brains. H e suggests that

C ulture . . . developed in the hominid line about three m illion years

ago. On the other hand, B onner (1980) entitled a chapter concerned

w ith m otility in b ac te ria T h e E arly O rig in s o f C ultu ra l E vo lu tio n, a nd

W ilso n (1 97 5:1 68 ) ha s su gge ste d th at cu lture , asid e from its in vo lv e-

m ent w ith lan gua ge, w hic h is tru ly u niq ue, differs fro m an im al tra ditio n

o nly in d eg re e.

C le arly , in atte mp ts to c ate goriz e soc ia l in flu enc es o n b eh av ior, a s in

o th er ta xo no mic e nte rp ris es , th er e a re b oth lu mp er s, lik e B on ne r a nd

W ilson (w ho regard all traditions as resting on sim ilar fundam ental

processes), and splitters, such as S ahlins (w ho w ould draw sharp

distinc tion s a mo ng typ es of tra dition s to be fou nd in d iffe re nt bra nch es

of the p hy lo gen etic tre e).

L ike Sahlins, I am of the splitter persuasion. U nlike S ahlins, I w ould

draw distinctions among types of traditions (of which culture is an

insta nc e) b ase d no t o n d iffe ren ce s in th e su pp ose d c om plex ity o f ve rte-

b ra te b ra ins, b ut o n d iffe re nc es in th e b eha vio ra l p ro cesse s th at su pp ort

p ar tic ula r tr ad itio ns ( Ga le f 1 98 8).

T rad ition an d C ultu re

In o rd in ary sp ee ch, a be hav io r de scrib ed a s trad ition al is o ne th at

has both been learned in some way from others and can be passed on to

n aive ind ivid uals (G ov e 1 97 1); the E ng lish w ord tradition d er iv es f ro m

t he L a tin traditio (L ew is a nd S hort 1 96 9), m ean ing th e a ctio n of ha ndin g

something over to another or of delivering up a possession. C onse-

q ue ntly , la be lin g a b eh av io r tr ad itio na l im plie s th at s oc ia l le ar nin g o f

some sort played a role in the acquisition of the behavior by those

ex hibiting it (G ale f 1 97 6, 1 99 0; N ishid a 1 987 ).

S om e anim al behaviorists have proposed that the w ords culture an d

tradition sh ould b e c on side red syn on ym s. F or e xa mple , [a n] in div id u-

aI's behavior can also be m odified by its m other or by the group in w hich

it is r ais ed . I f su ch s oc ia l m od if ic atio n s pre ad s a nd p er pe tu ate s a p ar tic u-

lar variant over m any generations, then w e have 'culture' in the broad

sense in w hich a student of anim als can use the term . . . . T he definition


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160 Human Nature, Vol. 3, No.2, 1992 T he Que st io n o f A nim a l C ult ur e

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states nothing about the precise m echanism of social m odification (be-

cause it is unknow n in m ost cases) (K um mer 1971:13).

K um mer's definition of culture, and others like it, rests on analogy

rather th an o n h om olo gy . T he d efin itio n ex plicitly accep ts as cu ltu ral all

t ra di ti on s, i .e ., a ll s oc ia ll y t ra nsm it te d modi fi ca ti on s o f b eh av io r, r eg ar d-

less of the processes that resulted in their propagation. For exam ple, a

scent trail that resulted in m any generations of a population of ants

follow ing the sam e path each day from nest entrance to feeding ground

w ould be defined as an agent for the propagation of culture. T his usage

seems to me to violate the usual meaning of the term

culture.

O n th e o th er h an d, G oo dall (1 97 3:1 44 -1 45 ) h as su gg ested th at w heth -

er behaviors may be considered to have been influenced by culture

depends on the m anner in w hich they w ere acquired by the individual,

i.e., th e k in d o f learn in g p ro cess in vo lv ed . A s a p sy ch olo gist, I m ig ht

wish to make finer distinctions than would Goodall regarding the

k in ds o f learn in g p ro cesses in vo lv ed in d ev elo pm en t o f a trad itio n to

decide whether a given traditional pattern of behavior was cultural.

Nonetheless, Goodall and I clearly wish to approach the problem of

d efin in g cu ltu re in th e sam e w ay (an d in co ntrad ictio n to th at p ro po sed

b y K um mer) in term s o f th e so cial learn in g p ro cesses su pp ortin g p ro pa-

g atio n o f b eh av io r.

C ulture in hum an populations is believed to be largely a result either

o f teach in g (see P rem ack 1 99 1 o r M ead 1 97 0 f or d iscu ssio n o f th e co ntri-

bution of pedagogy to hum an culture) or of learning by im itation (see

B oyd and R icherson 1985 for discussion). T here is little question that

hum ans are able to teach and that, even as infants, they can learn to do

acts sim ply by w atching others perform those acts. Indeed, I know of no

one who has questioned either assumption. Further, there is every

reason to believe that hum ans use their ability to im itate to acquire

p attern s o f b eh av io r th at fo rm a p art o f h u man cu ltu re (see, fo r ex am ple,

V ygotsky 1962; B andura 1977; Speidel and N elson 1989). T he relative

im portance of pedagogy and of learning by observation and im itation in

human acquisition of culture is an open question, but one that lies

beyond the scope of this paper.

On the other hand, a century of laboratory analysis of the learning

p ro ce ss es s up po rtin g tr ad itio ns in a nim als ( se e G ale f 1 97 6, 1 98 8, 1 99 0 f o r

review s) indicates that anim al traditions are generally a result of such

p ro ce ss es a s lo ca l en ha nc em en t ( a pp ar en t im ita tio n r es ultin g f rom

directing the anim al's attention to a particular object or to a particular

p art o f th e e nv ir onme nt ; T ho rp e 1 96 3:1 34 ) o r s oc ia l f ac ilita tio n, th e

energizing of responses as the result of the simple presence of con-

s pe cif ic s ( Cla yto n 1 97 8; Z ajo nc 1 96 5) , w hic h a re q uite d if fe re nt f rom th e

b eh av io ral m ech an ism s th at u nd erlie p ro pag atio n o f cu ltu re in h um an s

(see G alef 1988 for a review ). C onsistency in usage w ould require that

an im al cu ltu re b e d efin ed as an im al trad itio n th at rests eith er o n tu itio n

of one animal by another or on imitation by one animal of acts per-

fo rm ed b y an oth er.

T here are, o f co urse, d ifferen ces b etw een an im al trad itio n an d h um an

culture in addition to differences in the learning process that support

them . For exam ple, hum an culture accum ulates over generations and

can lead to in ven tio n an d tran sm issio n o f in creasin gly co mp lex b eh av -

iors. No one has claimed that any animal learns any behavior from

co nsp ecifics th at it co uld n ot learn in dep en den tly th ro ug h in teractio n

w ith its physical environm ent. W ith respect to the present definition,

th ese d ifferen ces b etw een th e trad itio ns o f a nim als an d th ose o f h um an s

are seen as co nseq uen ces o f d ifferen ces in acq uisitio n p ro cesses rath er

th an as d efin in g featu res.

T ea ch in g a nd Imita tio n

B ar ne tt ( 19 68 :7 48 ) p ro po se s th at to id en tif y te ac hin g w e n ee d e sta blis h

two things: first, the behaviour of the putative teacher m ust induce a

specific change in the behaviour of another. . ., second, the teacher's

behaviour m ust be persisted in, and perhaps adapted, until the pupil

a ch ie ve s a c er ta in s ta nd ar d o f p er fo rma nc e. Thor pe ( 1963 : 135) d ef in es

true im itation as the copying of a novel or otherw ise im probable act or

u tte ra nc e, o r s om e a ct f or w hic h th er e is c le ar ly n o in stin ctiv e te nd en cy .

As far as is known, no nonhum an anim al teaches, in Barnett's (1968)

sense of the term . E ven adult chim panzees rarely handle objects in such

a w ay as to engage the attention of infants (B ard and V auclair 1984; but

s ee B oe sc h 1 99 1 fo r in te re stin g o bs er va tio ns ). P ur po rte d e xa mp le s in th e

literature of tuition in anim als are restricted to a few observations

(m ostly o f p rim ates) eith er p rev en tin g in fan ts o r ju ven iles fro m co ntact-

in g p oten tially d an gero us o bjects (G oo dall 1 97 3; K aw am ura 1 95 9; M en -

zel 1966; Nishida et al. 1983) or encouraging an infant to walk by

m ov in g a sh ort d istan ce fro m it an d th en p au sin g (A ltm an n 1 98 0; M i lto n

1988). In the form er cases, neither the frequency w ith which the naive

are p rev en ted fro m co ntactin g desirab le o bjects b y ad ults n or chan ges in

th e b eh av io r o f th e n aiv e as a resu lt o f p urp orted teach in g ep iso des h av e

ever been assessed. In the latter, there is no evidence that the adults are

teach in g. A du lts m otiv ated b oth to lo co mo te an d to rem ain clo se to their

young m ight be expected to exhibit hesitant locom otory patterns, and

there is no reason to invoke tuition to explain their behavior. Conse-

quently, I find m yself in agreem ent w ith those (E wer 1969; H inde 1971;

P rem ack 1 99 1) w ho reject su ch o bserv ation s as ev id en ce o f p edag og y in

nonhum an anim als (but see Barnett 1968; Caro and Hauser 1991).

M ore contentious is the question of whether nonhum an anim als are


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T he Que st io n o f A ni ma l C ultu re

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able to im itate the behavior of conspecifics, and m ore specifically,

w hether any traditional patterns of behavior exhibited by m em bers of

som e groups of anim als living in natural habitats are, in fact, the result

o f l earnin g b y im itatio n. In term s o f th e ap pro ach to d efinitio n o f c ultu re

proposed above, the em pirical issue is w hether traditional behaviors

observed in som e groups of anim als are the result of im itation of one

animal by another and, therefore, cultural in the sense that term is

d ef in ed ab ov e.

In 1 95 3, an 1 8-m on th-o ld , fem ale m acaq ue (lm o) b eg an to tak e p ieces

of sweet potato covered with sand to a stream and to wash the sand

from the potato pieces before eating them . M ost Japanese m acaques

brush sand from pieces of sweet potato with their hands, but Imo

started to wash sandy pieces of potato in water and, during the next 9

years, sw eet-potato w ashing becam e com mon in her troop.

S weet-p otato w ash in g d id no t sp read ran do mly th ro ug h th e K osh im a

p op ulatio n o f m acaq ues; rath er, sp read o f th e b eh av io r fo llo wed lin es o f

s oc ia l a ff ilia tio n. F ir st, p ota to w as hin g w as e xh ib ite d b y Imo 's p la ym ate

Semushi, who began to wash potatoes a month after Imo did. Sweet-

potato washing was then performed by Imo's mother (Eba) and by a

second playm ate of Im o's (U ni), both of w hom began to w ash potatoes

three months after Semushi began. During the following two years

(1955--1956), seven m ore youngsters learned to w ash potatoes, and by

1958, 14 of 15 juveniles and 2 of 11 adults in the Koshima troop had

started w ashing potatoes (ltani and N ishim ura 1973; K aw ai 1965; K a-

w am ura 1 95 9; N ish id a 1 98 7). A cco rdin g to th e seco nd ary literatu re, th e

spread of this behavior occurred because naive m onkeys observed Im o

and others w ash sw eet potatoes and then im itated them ; sw eet-potato

w as hin g w as cu ltu ra l.

It w ill, of course, never be know n w ith certainty w hat caused sw eet-

potato washing to spread through the Koshim a troop of m acaques 40

years ago. Possibly, some or all of the monkeys did learn to wash

p otato es b y im itatin g eith er Im o, th e in itiato r o f th e b eh av io r, o r o thers.

Interpretation of the spread of w ashing behavior through the K oshim a

troop of m acaques as the result of im itation learning, however, can be

questioned.

One property of sweet-potato washing that makes it seem a likely

can did ate fo r p ro pag atio n b y im itatio n is th e b izarreness o f t he b eh av io r

and the intuitive im probability of m any. m onkeys learning indepen-

dently to w ash potatoes. It is, therefore, surprising to find that sw eet-

potato washing has been observed in four other provisioned troops of

Japanese m acaques in addition to the troop at Koshim a (Kawai 1965).

Im o w as n ot as creativ e a g en iu s as th e secon dary literatu re su gg ests,

an d po tato w ash in g is n ot as u nlikely a b ehav io r fo r m on key s to d ev elo p

independently as one m ight im agine.

R ecen tly , V isalb erg hi an d F rag aszy (1 99 0b ) h av e rep orted v ery rap id

learn in g o f fo od w ash ing b y b oth cap tiv e crab -eatin g m acaq ues

(Macaca

fascicularis) an d cap tiv e tu fted cap uch in m on key s (Cebus appella). Appar-

en tly , fo od -w ash in g b eh av io rs are learn ed relativ ely easily b y m on key s

and can become common in a troop through processes other than

im itation of a rare creative genius. Even if m onkeys find it easy to

learn to wash food in appropriate circumstances, however, it is not

obvious why sweet-potato washing became widespread among ma-

caques at Koshim a and not am ong those found elsewhere.

C reene (1 97 5) su gg ests th at m ain ten an ce o f sw eet-p otato w ash in g in

PU RPO RT ED E VID EN CE OF C UL TU RE

IN A NIMA LS

The t erms c u l t u r e an d imitation a pp ea r in t he i nd ic es o f m o st c on tempo-

rary introductory texts in anim al behavior. O n the relevant pages, one

usually finds an account of one or more locale-specific behaviors: of

chim panzees in C om be N ational Park using tw igs as tools to f ish for

te rm ite s ( Co od aI l1 98 6) , o f J ap an es e m ac aq ue s o n K os him a I slan d w as h-

ing sweet potatoes (Kawai 1965; Calef 1990), or of various species of

sm all birds in England opening m ilk bottles and drinking cream from

th e su rface (F ish er an d H in de 1 949 ; S herry an d C alef 1 98 4, 1 99 0). T ex t-

book accounts of the developm ent and spread of these behaviors often

lead the reader directly to the conclusion that the only explanation for

the existence of idiosyncratic behaviors in som e prim ate troop or bird

flock is their spread from one individual to another by im itation learn-

ing. For exam ple, regarding the C om be chim ps, Bonner (1980:172) re-

po rts th at su ccessfu l fish in g fo r term ites req uires a nu mb er o f s kills an d

especially know ledge about w here to poke and w hat kind of stick is best

an d h ow to tw id dle th e stick . T hese acco mp lish ments are clearly learn ed

by im itation and are passed dow n as cultural traditions. T here are,

how ever, alternatives to this selective recounting of observations of

d ifferen ces in th e b eh av ior o f m em bers o f d ifferen t an im al p op ulatio ns

( Ca le f 1 97 6, 1 99 0; N is hid a 1 98 7) .

B elow , I discuss tw o of the m ost frequently cited instances of anim al

culture, sw eet-potato w ashing and term ite fishing. It is m y intention to

q uestio n th e v alid ity o f th e u su al tex tb oo k in terp retatio n o f th ese b eh av -

io rs a s in sta nc es o f lea rn in g b y im ita tio n an d, c on se qu en tly , a s in sta nc es

o f a nim al c ultu re .

S weet-P otato W ash in g b y Jap an ese M acaq ues

a t K o sh ima


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T he Que st io n o f A nim al C ult ur e

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the K oshim a troop m ight not be a result of natural processes. For m any

years, the K oshim a troop has been provisioned by caretakers, local

pe~ple employed to supplem ent the natural diet of the monkeys w ith

a gn cu ltu ral p ro du cts: sw ee t p otato es, w he at, pe an uts, etc . W he n G re en

v isite d K osh im a in the 1 97 0s, h e o bse rv ed th at th e w om an p ro visio ning

the macaques, who had been a. caretaker for many years, gave sweet

potatoes only to those m onkeys that w ashed them . S he thus rew arded

m onkeys for w ashing sw eet potatoes. G reen suggests that hum an inter-

vention may have maintained potato w ashing in the K oshim a troop,

w hereas it died out in other troops because the individuals that w ashed

po ta toe s w ere n ot re wa rd ed .

G reen (1975) also points out that, w hile foraging, a m acaque troop is

sp atia lly o rga niz ed in a w ay th at inc re ase s o r d ec rea se s th e lik eliho od of

in div id uals be in g c lose to o r d istan t fro m a h um an p ro visio ne r a cco rd in g

to the m acaque's age class and m atriline. H ence, hum an intervention

could produce a pattern of spread of w ashing behavior that w ould m ake

the behavior appear to an unsuspecting observer to be a result of

im ita tio n le arn ing . O f c ourse , e ven if p ota to w ash ing w as m ain tain ed in

the 1970s by caretakers, it m ight originally have spread by im itation

learning. A few things, how ever, m ake m e question this proposition.

F irst, som e loc ale -sp ec ific b eh av io rs see n in th e K osh im a tro op, cle ar-

l~ ~ot the result of im itation learning, spread in a fashion strikingly

sim ilar to sw eet-p otato w ash in g. C onsid er b ath in g be ha vio r. B efo re th e

summer of 1959, none of the members of the Koshima troop would do

more than dip their hands and feet in the sea. That summer one of the

caretakers, M rs. M ito, induced a 2-year-old m ale (Ego) to w alk into the

w ater of O tom ari B ay by throw ing peanuts (one of Ego's favorite foods)

into the sea. Over a period of 3 years, M rs. M ito induced 63% of the

K oshim a m onkeys to enter the water.

Japanese scientists observed and described the spread of bathing

b eh av io r. L ik e sw eet-p ota to w ash in g, b ath in g b eh avio r w as o rigin ate d

by

~

juvenile (Ego) and spread through the originator's peer group to

their m others and then from those m others to their young (K aw ai 1965).

O rd er ly s pr ea d o f a b eh av io r a lo ng m atr ilin es is n ot n ec es sa rily e vid en ce

e ithe r o f im ita tion o r o f c ulture .

S econd, tw o param eters of the spread of sw eet-potato w ashing, usu-

ally unm entioned in published descriptions of the behavior, lead m e to

su sp ect th at so cia l le arnin g m ay h av e h ad little to d o w ith th e pre va le nc e

of sw eet-potato w ashing at K oshim a. O ne probable advantage of social

le ar nin ? o ve r tr ia l- an d- er ro r le ar nin g is th at s oc ia l le ar nin g is m ore r ap id

tha n tn al-a nd -e rro r le arn in g. O ne sig n of so cia l le arn in g sh ou ld , the re -

fore, be relatively rapid spread of a behavior through a population.

Im o in ve nte d sw ee t-p ota to w ash in g in S ep tem be r 1 95 3, w he n sh e w as

18 m onths old. W ithin several years, eight mem bers of the K oshim a

troop Imo's age or older eventually began to wash potatoes. One of the

eight, Semushi, began to wash potatoes in October 1953. Two other

troop m em bers, U ni and Im o's m other E ba, started in January 1954. T he

rem aining five of the eight m onkeys that acquired the behavior began to

w ash potatoes in 1955 (n

=

1 ), 1 95 6 (n =

2), and 1957 (n

= 2). B oth the

mean and median tim es for acquisition of sweet-potato w ashing (for

those w ho ever developed the behavior) w ere roughly 2 years after Im o

started to dem onstrate it. I consider this painfully slow propagation of

behavior to be inconsistent w ith the hypothesis that the behavior w as

le arn ed b y im ita tio n. W hea t p la ce r m in in g, a se co nd o fte n-c ite d, loc ale -

specific behavior of the K oshim a troop, spread even m ore slow ly than

sw eet-p otato w ashin g (K aw ai 19 65 ; N ish id a 1 98 7).

T hird, m ost m odels of social learning assum e that the probability of

acquiring a socially transm itted behavior should increase w ith an in-

crease in the number of models engaged in that behavior (Boyd and

R icherson 1985). In other w ords, other things being equal, the rate of

recruitm ent to a behavior should be positively correlated w ith its fre-

quency of occurrence in a population, until saturation occurs.

I n f ac t, K aw ai's ( 19 65 ) d ata r ev ea l th at

(a )

th e p oo l o f p ote ntia l le arn er s

re ma in ed e sse ntia lly c onsta nt o ver th e ye ars, (b ) the num ber of dem on-

s tr ato rs r os e d ra ma tic ally , y et (c) th e ra te o f rec ru itm en t to th e b eha vio r

did not increase (see G alef 1990 for further detail). These data do not

suggest that im itation learning w as responsible for the developm ent of

potato washing in the individuals that cam e to exhibit it.

L as t, c on sid er K aw ai's o wn s ta te me nt ( 19 65 :8 ) o f th e o bs er va tio ns th at

led him to suggest that social interactions were responsible for the

a cq uisition o f th e b eh av io r by ju ven ile m ac aq ue s.

5w eet-potato-w ash ing m onkey s e at potatoe s at th e e dge of w ater. S o tha t

the potato skin is scattered around at the bottom of w ater. Babies, w ho

have the experience of eating potatoes in water at the beginning of the

developm ent of feeding behavior, are conscious of the association of

potato w ith w a~ er. In the proce ss of learning, e ating potato by pickin g it

up out of water is to them equally on a level w ith eating natural food.

Being alw ays w ith m others, babies stare at their m others' behavior

w hile m others are doing sw eet-potato-w ashing behavior. In this m an-

ner, infa nts a cquire sw eet-pota to-w ashing beh avio r through m others'

behavior.

The question is whether any, all, or only one of the interactions

m en tio ne d by K aw ai w ere n ec essa ry fo r th e slo w sp rea d o f s w ee t-po ta to

w ashing through the K oshim a troop. The question cannot be answ ered

b y u nob tru siv e ob se rva tio n o f the m on ke ys. S ure ly , un ob tru siv e o bse r-


6/12

166

Human Nature, Vol. 3, No.2, 1992

T he Que sti on o f A nim a l C ult ur e 167

v atio n d .o es n ot d em on strate th at im itatio n o f o ne an im al b y an oth er w as

responsIble for propagation of the behavior, as so m any secondary

s ou rc es h av e s ug ge ste d.

the fact that chim panzees at G om be are m ore likely to use both ends of a

prob e before discarding it th an are chim panzees at A ssirik in Senegal

(West Africa) or that the bark is usually peeled from twigs used as

probes by chim panzees at Assirik, whereas those found in Gom be are

not peeled (McGrew et al. 1979). Of course, the present lack of an

ecological explanation for locale-specific behaviors cannot be u sed to

infer that they are the result of im itation learning (Tom asello 1990).

S ub tle e co lo gical facto rs m ay ex plain all su ch d ifferen ces in b eh av io r.

In deed, as discussed in the next section, it is d ifficult to im agine how a

locale-specific behavior, such as peeling bark from a probe, could be

sustained in a population in th e absence of rew ards for that behavior in

the particular area in w hich it occurred.

A F ie ld Experiment. A lt ho ugh t he s kil ls u se d b y c him pan ze es t o f is h

fo r in sects ap pear at first g lan ce to b e relativ ely u nso ph isticated , T elek i

(1 97 4:5 85 -5 88 ) rep orts th at w hen , af ter m on th s o f carefu l o bserv atio n o f

G om be chim panzees fishing for term ites, he tried to fish for term ites

him self, he was unable to locate tunnel entrances of term ite m ounds

consistently, to select twigs or grasses of the proper rigidity to use as

probes ( D espite m onths of observing and apin g adult chim panzees as

they selected probes with enviable ease, speed and accuracy, I was

unable to achieve their level of com petence ), and to catch term ites

efficiently by probing their tunnels. T eleki concludes (1974:587) that

each stage of a particular com plex [of insect fishing] m ay w ell have to

be learned via a cultural tradition that is passed from individual to

in div id ual w ith in a p op ulatio n. T elek i's o wn failed attem pts to learn

to f is h f or te rm ite s e ff ic ie ntly b y o bs er vin g th e b eh av io r o f a cc om plis he d

adu lt chim panzees seem to contrad ict h is interpretation. U nless chim -

panzees are m ore proficient than doctors of philosophy atjearning

term ite-fish in g tech niq ues b y im itatio n, o bserv atio n o f p ro be selectio n

and probe m anipulation by adults cannot in itself lead to developm ent

of efficient term ite fishing by young chim panzees at Gom be or else-

where.

Termite Fishing by himpanzees

at G om be N ation al P ark

F i e l d Observations.

Chimpanzees in Gombe National Park in Tan-

za nia cap tu re term ites u sin g tw ig s o r b lad es o f g rass as to ols to p ro be th e

passageways of the term ites' earthen m ounds. W hen the insects react

defensively to an intruding probe, biting and clinging to it, the chim -

p anzees carefully extract the probe and eat any term ites that they fin d

clin gin g to it.

N early all m em bers of the G om be stud y po pulation that are m ore than

5 years old fish for term ites for 1 to 5 hours per day during October and

N ovem ber. Sim ilar m ethods of probing for insects w ith tw igs, vines, or

grasses have been observed in all chim panzee com munities studies in

E ast A frica, as w ell as in so me, b ut n ot all, ch im pan zee g ro up s o bserv ed

in W est A frica (M cG rew and R ogers 1983; M cG rew et al. 197 9). T here is

also variation am ong chim panzee populations in the species of ant or

term ite for which they fish, in the m aterials used as probes, and in the

ways in which probes are prepared for fishing.

G oo dall (1 98 6:5 61 ) h as su gg ested th at Y ou ng ch im pan zees learn th e

to ol u sin g p attern s o f th e co mm un ity d urin g in fan cy , th ro ug h a m ix tu re

o f so cial facilitatio n, o bserv atio n, im itatio n, an d p ractice-w ith a g oo d

deal of trial and error learning thrown in. Secondary sources often

considerably truncate G oodall's analysis and suggest that learning by

im itatio n an d cu ltu re are resp on sib le eith er fo r d ev elo pm en t o f ter-

m ite fishing generally or for developm ent of the v ariations in term ite

fish in g tech niq ue to b e fo un d in d ifferen t co mm un ities o f ch im pan ze es

( Bo nn er 1 98 0; M cF ar la nd 1 98 5) .

T he ~e is little q ue stio n th at s om e o bs er ve d d if fe re nc es in in se ct- fis hin g

b eh aV io r are re ad ily ex plain ed eith er as resp on ses to d ifferen ces in th e

b eh av io r o f v ario us sp ecies o f in sect p rey (M cG rew et al. 1 97 9; N ish id a

an d U eh ara 1 98 0) o r as d ifferen ces in th e av ailab ility o f m aterials u sed as

probes (M cB eath and M cG rew 1 982). For instance, the genus of term ite

for which the Gom be chim panzees fish is absent from the m ain study

area at M ah ale, an d th e term ites p resen t at M ah ale p ro du ce a d istastefu l

d efen siv e secretio n th at p ro tects th em fro m ch im pan zee p red atio n (C ol-

lins and M cG rew 1987; Nishida and Uehara 1980). It is therefore not

necessary to invok e t radition to explain the fact that G om be chim -

panzees fish for term ites and M ahale chim panzees do not.

O n th e o th er h an d, n o eco lo gical ex plan atio n is cu rren tly av ailab le fo r

Imi ta ti on b y Ch impan ze es i n Capt iv it y. If it had been shown in the

lab orato ry th at ch im pan ze es co uld learn to so lv e p ro blem s b y o bserv in g

an d th en im itatin g th e b eh av io r o f su ccessfu l co nsp ecifics, th en it m ig ht

b e a b it p ig -h ead ed to in sist th at free-liv in g ch im pan zees d o n ot u se th eir

ability to im itate to learn to fish for insects. Evidence of an ability of

chim panzees (or of other prim ates) to learn novel b ehaviors by ob serv-

in g a nd th en im ita tin g t he ir f ellows ( re vi ew ed r ec en tly a nd th ou gh tf ully

in b oth T om asello 1 99 0 an d V isalb erg hi an d F rag aszy 1 99 0a), h ow ev er,

is su rp risin gly lim ited , alm ost en tirely an ecd otal, an d as d iscu ssed b e-

lo w, p ro bab ly irrelev an t to u nd erstan din g th e sp read o f g oal-d irected

b eh av io rs lik e f is hin g f or in se cts .


7/12

1 6 8

T he Q ue st io /J o f A /J im a l C ul t u r e

1 6 9

H um an N atu re ,

V o l 3 N o 2 1 9 9 2

. yp ic al o f d e sc rip tiv e re ports of im ita tio n b y c him pa nz ee s a re th ose o f

Kohler (l?5::8~, 280) and, m ore recently, those of de W aal (1982, in

p re s s) . o f Im i ta t. IOn ~ f

loc om oto ry p atte rn s b y c him pa nz ee s in o the r th an

g oa l- dI ~e cte d s Itu atio ns . F or e xa mp le , d e W a al ( 19 82 :8 0) r ep or ts : K ro m

means .crooked.' H er body is distorted and she has a hunched-up way

of walkmg. . . . The young apes. . . Once had an 'ape Krom' craze. For

days

o~

end .they w ould w alk behind her, single file, all w ith the sam e

pathetic carnage as Krom . . . .

In go al-dire cted .c ircu ~sta nc es, im itatio n is n ot a s ea sily se en in ch im -

pa nz ee ~. C ~n c~ rn mg c hIm pa nze es' im ita tio n o f n ove l, m ea nin gful ac ts

(of whIch fishmg for termites would surely be an example), Kohler

(1 95 9:1 8) ~ ep orts, U nfortu na te ly , th is is a ve ry ra re o ccu rre nc e, ev en

am o~g chlm pan~ee~, and w hen it does occur, the situation, as w ell as its

solu~on, must he Just about w ithin the bounds set for S

p

ontaneous

solution.

K oh le r ( 19 59 ~e mp ha siz es ~ wo lim its o n im ita tio n le ar nin g o f m ea nin g-

ful a~ts by chlm 'panzee~: fIrst, the chimpanzees have to be able to

pe rc eIv e t~ e cru ~Ia l re la tIO nsh ips le ad ing to so lu tio n of a p ro ble m, a nd

se ~on d, na rv e. a m~ als c ann ot ~ im ply c opy m ov em en ts m ad e b y a sk ille d

ammal.

. hat

I S, c hI mp an ze es m p ro ble m-s olv in g s itu atio ns im ita te o nly

what K ohler called the substance of an action (the purpose of the se-

q ~e~ ce o f ~ ov em en ts), n ot its f o r m ( th e moveme nts th em se lv es ). I t is

dlf~ cu lt to I~ ag in e a s~ tu atio n. in w ~ic h o bse rv atio n is le ss like ly to lea d

to p e:c ep tio n o f c ru CIa l r ela tio ns hI ps o r in w hic h th e s ub sta nc e o f

an acti~n woul~ be ~ore, o?scure than it is in termite fishing.

C on ~I ste nt.w lth K oh le r s m te rp re ta tio n, T om as ello e t a l. ( 19 87 ) f ou nd

that naIve chlm fan~ees that observed a trained conspecific use a rake to

reach food outsIde ItS cage w ere m ore likely to learn to use the rake for

the. sam e purpose than w ere naive chim panzees that lacked this obser-

v atio na l.e xp erie nc e. T he o bserv ers d id no t use the sam e m oto r pa tte rns

that theIr dem onstrator had used, how ever. A cquisition of the motor

p~tterns needed to obtain food efficiently w as the result of individual

tnal-and-error learning (see also Sum ita et al. 1985).

enhancem ent, and trial-and-error learning on the developm ent of be-

h av io r a re w ell e sta blish ed. E vide nc e o f a c on trib utio n o f i m itatio n to th e

a cqu isitio n, e ve n b y ch im pan ze es, o f p ro ble m-so lvin g b eh av io rs (su ch

as term ite fishing) is w eak (T om asello 1990).

A s is th e c ase w ith sw ee t-p ota to w ash in g, it se em s in tuitiv ely im pro b-

a ble tha t e ach c him pa nz ee d isc ov ers for itse lf th e e ffec tiv en ess of usin g

twigs or blades of grass to fish in term ite mounds for food. it is,

how ever, easy to underestim ate the com plexity of the m otor patterns

that infant chimpanzees develop in the course of their unrew arded

( pla yf ul) in te ra ctio ns w ith th e p hy sic al e nv ir on me nt ( Birc h 1 94 5; M en ze l

e t a l. 1 97 0; S ch ille r 1 95 2, 1 95 7).

D ev elop me nt o f F ish in g B eha vio r

O ~e m ight reasonably. ask, given. that I question the view that young

c hIm pa nz ee s le arn to frsh fo r te rm Ite s b y im ita tin g a du lts o f th eir tro op

how w ould I explain the existence of the behavior and its variants? i

w ould answ er that I accept G oodall's (1986:561) explanation of the

devel~p~e~t of term ite fishing (quoted above), except that 1 w ould

le av e Im Ita tio n o ut o f th e a na ly sis. T he e ff ec ts o f s oc ia l f ac ilita tio n, lo ca l

U nfo rtu na te ly w e k no w little of th e de ve lop me nt o f b eha vio rs u sed by

chim panzees w hen fishing for insects. A t G om be, young chim panzees 2

to 5 years old typically accompany their mothers when they fish for

inse cts, p lay w ith th eir m oth ers' disc arde d p ro bes, a nd e xh ibit a du ltlike

competence in term ite fishing when they are only 5 to 6 years of age.

G oodall (1986) reports that infant chim panzees at G om be frequently

play w ith ants, often poking at them with tiny tw igs. Infant chim-

p an ze es also use stick s to in ve stig ate h ole s in tre es. W hile still a n in fa nt,

F lin t, a G om be c him p,

'fish ed' a s th ou gh fo r te rm ite s in th e h airs o f h is

mother's leg. . .[and] when he was four years old, used these fishing

te ch niq ue s w he n d rin kin g w ate r fr om a h ollo w tr ee ( Go od all 1 98 6:5 63 ).

G oo da ll su gg ests th at in th ese ca se s F lin t w as e xhib itin g term ite fish in g

in n ove l c onte xts. B ec au se in fa nts do n ot fish for te rm ite s (T ele ki 1 97 4), 1

c on sid er G oo da ll's d es crip tio n o f F lin t's b eh av io r ill- co ns id er ed . P lu ck -

ing blades of grass or tw igs, sticking them in holes and then into one's

m outh, chasing ants w ith them , etc., are behaviors that probably devel-

o p in all y ou ng c him pa nze es d uring the ir sp onta ne ou s in te ra ctio ns w ith

th e p hy si ca l e nv ir onm en t.

If probing in holes w ith tw igs or blades of grass em erges in the course

of norm al chim panzee developm ent, then interaction w ith adult chim -

panzees fishing for term ites m ight w ell bias infants or juveniles to use

these m otor patterns to probe in tunnel entrances that w ere a focus of

a du lt a ctiv ity . T he p rese nc e o f pro bing im ple men ts a ba nd on ed b y ad ults

n ea r te rm ite n ests th at a dults w ere ex plo itin g m ig ht inc re ase th e p ro ba -

bility that young chim panzees would employ those im plem ents to ex-

p lo re a du lt-c re ate d o pe nin gs in te rm ite m ou nd s. A ny p ro bin g o f term ite

tunnels by naive juveniles w ould be rew arded, and thus m aintained, by

th e oc ca sio na l c ap tu re o f te rm ite s. D iffere ntia l re wa rd follo wing u se o f

A N A LTER NATIVE V IEW


8/12

17 0

Human Nature, Vol. 3, No.2, 1992

T he Q u e st io n o f A nim a l C u l t u r e

17 1

a

.

sh

P

a

P

p

ropnat

f

e pro bes a nd a pp ro priate fish ing te chn iq ues co uld

g

raduall y

e per ormance (Galef 1980

)

fI

.

posefully fishin f

.

un 1 young chImpanzees were pur-

opened by o th e~s ~~ t~ e i: ;~ :~ e~t~h~~u~~nn :~~~~y

e xp lo ri ng t un ne ls

nothing of the forces that either shaped the development of those

behaviors or m aintain them . The inference of culture influence rests

entirely on the absence of inform ation concerning the ontogeny of the

behaviors in question. M cGrew et aI. (1979:207) are sensitive to this

problem , indicating that further data are needed. W e are fortunate

th at, in th e c ase o f te rm ite -fish ing ch im pa nz ee s, th ere is o pp ortu nity to

co ll ec t addi ti on a l ob se rva ti on s.

In m y v ie w, alth oug h im ita tio n m ig ht intro duc e so me n ov el b eh av io r

into the re pe rto ire s o f m em be rs o f a p opu la tion , th ro ug h tim e (p rob ably

counted in days) this behavioral novelty w ould be m aintained, m od-

ifie d, o r e xtin guish ed d epe nd in g o n its e ffe ctiv ene ss (re la tiv e to a va il-

able variants) in acquiring rew ards. T here is no reason to believe that

in ef fic ie nt b eh av io rs in tro du ce d so cia lly in to a nim al p op ula tio ns a re a ny

m or e re sis ta nt to e xtin ctio n o r m od if ic atio n th an a re in div id ua lly le arn ed

b eh av iors. F or ex am ple , le arnin g b y im itatio n, if it w ere to ex ist, w ou ld

n ot n ec es sa rily o ff er a c om pe llin g e xp la na tio n o f th e s ta ble d if fe re nc es in

the w ays tools are m ade for insect fishing by chim panzees in different

parts of A frica (M cG rew et al. 1979). There m ay be differences in the

environm ents occupied by different troops of chim panzees that m ain-

ta in d iv er sity in to ol c on str uc tio n o ve r d ec ad es. T he id ea o f a p op ula tio n

of 20-year-old chim panzees using an inefficient m ethod to prepare

p rob es for te rm ite fishin g be ca use , a s in fan ts, th ey w atc he d th eir m oth -

ers do so, is at variance w ith what is known of the ways in which the

behavior of animals tracks environmental demands. The burden of

pro of rests o n tho se pro posin g u nlik ely e xpla natio ns.

I nte ra cti~ ~s b etw ee n S oc ia l L ea rn in g

an d In dIv Id ua l L ea rn ing

The d'

rece m g ~ccount of the developm ent of term ite fishing in ch'

_

panzees,

.sp~culatIve though it m ay be, presents tw o de artures fr~:

;~~7~~~~:~~~~~;

f%~~g ::~~~t;:::~;:;f

~~::d~sg~::~~~

.

IV I u a earnmg processes (see also Tomasello 1990) S

_

~~dhlt

sU

d

gg

b

ests

h

t~a t s oc ia ll y l ea rned behav io rs a re modi fi ab le a nd ;~l

s ape y t elr consequences.

lo~:t;/w~

P rohos it ions . ar e, I bel ie ve , wel l e st ab li shed i n t he psycho -

ex

1

1 e ~a ure ut often Ignored in discussions of anim al tradition F or

amp e, m a recent

P

a

p

e R

(1988

.

I

.

'. .

r, ogers :822) proposes that when all

e ar :u ng I S s ? cl al,

~o one IS m onitoring the environm ent, and the infor-

~ atio n ~ cq Ulre d w Ill e ven tu ally b e w orth le ss. Th is ap pro ac h im 1 .

t

t

o

a

b

t

e

sOo.al

l

an

d

~

in div id ua l le arn in g a re in de pe nd en t e ntitie s se ~m s~ ~~ g

e

lS ea mg.

'

en~:d~;i~~a~

organisms

behave.. T he~r behavior is m odified by experi-

.

o nse q~ e~ ce s o f th eIr a ctIo ns (re in fo rc em en ts ).

Social' fl

_

;~;~:;~~h~~~ss~~aI l~~~~~~~~

~i~~t~~:~t:~~~~~;ea~~:e~~~~l:~:::~~;~

:t~~~;~~a

p

l

::~~:~~~Ir~

Unle

h

s s s oc i~ ll y i ~d uc ed a ct io ns a re r ei nf or ce d

11 y an ot er actIons m an individual'

.

~;eve

tin

. r, s ~C l

h

'a l~ y le ar ne d b eh av io rs , lik e a ny o th er le ar ne ~r :~ ~~ :~ ~,

ex gUlS m short order.

'

Some have su

gg

ested

(

f

d'ff'

see, or example, McFarland 1985'513) th t

~ ~~; :~~ / ;: ;s tho~d~~~

i ns ec t c a

b

Pt~~e exhib i ted

~ y ~ himp an z~ es l iv i: g

th

nca may e learned by Im Itation and assed

.

d

roug

d

h th e p op ul~ tio n b y c ultu ra l tra ditio n. O ne e xa m

p

l e o f cu l~u ra ll

y

uce vanation m tool u

.

b

M

(1979) .

se gIven y cFarland is McGrew et ai's

report mention~d above that chim ps in East A frica do not oft~n

~el bark. from the tW IgS t hey use in termite fishing whereas chim s in

be~:tviAfri~a

fr~ qu en tly d o. M cG re w et a l. (1 97 9:20 6-20 7) a lso se th is

cultu

o~a va;ance as one of only tw o instances in w hich they believe

r~ pr~ erence predom inates over environm ental dem ands in

p r~ duo ng d Iffe ren ce s in th e b eha vior o f c him ps livin g in d iffere nt a re as

diffe :~:~ sc ~~ f;~ ; ~ h~ t I.

am

tO

h

t.

e nt ir el y c onv ince d. Obse rvat ion s o f

e aVlOr 0 c Impanzees in different locales tells us

Summary

G oo da ll ( 19 70 :1 61 ) o nc e s ta te d, U nd ou bte dly , g iv en th e in ve stig ativ e

and m anipulative tendencies of the young chim panzee and his ability to

learn through trial and error, alm ost all of the feeding and tool using

behaviors I have described could be invented anew by each individual,

especially since the behavior of others in his group w ill serve to direct

h is a tte ntio n to th e re le va nt p arts of the e nviro nm en t. I a gre e w ho le -

heartedly. On the other hand, I see no reason to accept either the

premise or the conclusion of G oodall's next sentence: H ow ever, in a

s pe cie s w hic h is so w ell k no wn f or its im ita tiv e a bilitie s it s ee ms s en sib le

to suppose that m ost, if not all, of the behaviours outlined above. . . are

passed dow n from one generation to the next through observational

lea rn ing in a so cial c on te xt.

L ik e V isa lbe rg hi a nd F ra ga szy (1 99 0a ) a nd T om ase llo (19 90 ), I fin d no

c onv in cin g e vid en ce in th e litera tu re th at m on ke ys or a pes in ge ne ra l, or

c him pa nz ee s in p artic ular, c an lea rn b y im itatio n to u se pa rtic ula r m oto r


9/12

172

e Q ue st io n o f A nim a l C ult ur e

17 3

u man N atu re, V ol. 3 , N o.2 , 1 99 2

sk i~ ls in p ro blem -so lv in g situatio ns. C on seq uen tly , I h av e n o reaso n to

b e~ Ie ve th at b eh av io rs a ss oc ia te d w ith f is hin g f or te rm ites a re c ultu ra l in

c.h H~ pan zees.. S urely , g iv en th e cu rren t state o f th e ev id en ce, term ite

fishmg

b y. ch Im pa~ z~ es .d oes n ot w arrant d iscu ssio n as a p ro to ty pical

exam ple eIther of Im ItatIon or of culture in anim als.

m alogous features of the behavioral repertoires of vertebrates, then

:ulture is not a trait w hose antecedents can be traced back into the early

'eaches of the vertebrate line and beyond. W e do not know when the

n te lle ctu al a bilitie s n ec es sa ry f or le ar nin g b y im ita tio n a nd f or te ac hin g

first aro se. In deed , as S ah lin s (1 97 6) su gg ests, th e in tellectu al ab ilities

supporting learning by im itation, teaching, sym bolic language, etc.,

may have developed to the point where culture could develop only

w ithin the hom inid line; there m ay, in fact, have been no culture before

th e h om in id line ev olv ed ,

Given this view, there is no reason to treat culture as a trait that

evolved out of prim itive antecedents. Through evolutionary time, a

p op ulatio n o f o ur direct an cestors m ay h ave b eco me in creasin gly lik ely

to e xp re ss c ultu re a s a c on se qu en ce o f s ele ctio n f or in cr ea se d s op his tic a-

tion in intellectual processes that served other functions and only later

cam e to play a role in cultural transm ission. After the thresholds for

culture had been crossed, once our hypothetical ancestral hom inid w as

ab le to im itate o r to teach , th en selectio n fo r in creased ab ility to p artici-

p ate in c ultu re ( fo r in cr ea se d d oc ility , in S im on 's [ 19 90 ] te rm in olo gy )

w ould have led to elaboration of intellectual processes supporting cul-

tural transmission. In this model, continuity would be found in the

e vo lu tio n o f p sy ch olo gic al p ro ce ss es n ec es sa ry f or c ultu re , n ot in c ultu re

itself.

Darwin rem arked both that there is no fundam ental difference be-

tw een m an an d the h ig her m am mals in th eir m en tal facu lties (1 87 1:3 5)

and that the difference between the m ind of the lowest m an and that of

th e h ig hest an im al is im men se (1 871 :1 04 ). O ne h un dred an d tw en ty

years later, our understanding of the relationship betw een the m ental

facu lties o r m in ds o f h um an s an d o f th eir closest p hy lo gen tic rela-

tions is little more consistent than was Darwin's. In the preceding

discussion of culture, I have emphasized differences in human and

anim al m ental processes, where others m ight choose to em phasize

s im ila rities . F ur th er e xp lo ra tio ns in c om pa ra tiv e p sy ch olo gy p ro vid e o ur

o nly m ean s to im pro ve o ur u nd erstan din g o f w hy th e b eh av io ral cap aci-

ties of members of our own species appear both so similar to and so

d ifferent fro m th ose o f o ur fello w p rim ates.

ON LUSIONS

T h.ose w ho fa~ or a co nserv ~tiv e ~ pp ro ach to d escrip tio n an d an aly sis o f

a~ um al b eh av IO r, as I d o, fm d lIttle satisfacto ry evid en ce th at an im als

eIt~ er teach o r l~ arn b y im itatio n. L ocale-sp ecific beh av io rs, co mm on in

~n~m~l populatIons, do not provide evidence either of tuition or of

Im It~tion (G alef 1990). B oth analyses of field reports and laboratory

s tu dIe s o f s oc ia l- le ar nin g p he nome na s ug ge st th at a nim al tra ditio ns r es t

o n .p ro cesse~ ~ uite d ifferen t fro m th ose su pp ortin g cu lture in h um an s.

A mm al tradItIons are, theref?re, analogs rather than hom ologs of hu-

~an culture. Consequently, It can be m isleading to speak of an evolu-

tio n o f cu ltu re in anim als (e.g ., B on ner 1 98 0); th is u sag e su gg ests h om ol-

ogy w.hen there is evidence only of analogy.

.

It

n :' I gh tb e a rg ued th at it is n o m or e m is le ad in g to ta lk a bo ut c ultu re

mammals and humans than it is to discuss the win

g

s of bi d

d

b t th

r s an

a.

s or e eyes of vertebrates and insects. All three cases involve

usm g the sa~e label for analogous features rather than for hom ologous

ones. T here IS no problem w ith using the labels w ings or eyes to

re~ er to an alo go us stru ctu res, h ow ev er, b ecau se n o o ne su gg ests th at b at

~mgs evolved from bird wings or that vertebrate eyes evolved from

~~verteb:,a e on~s. W ould that the same were true in discussions of

culture mammals and humans.

Discussion of anim al analogs of hum an culture as though they were

~om ologs of hum an culture has the potential to lead students of culture

m to the sam e error m ade by com parative psychologists during the 1950s

and 1960s, when they trie~ to create a phylogeny of intelligence by

o rd erm g th e learn mg cap a~ ltIes o f an im als (tu rtles, g oldfish , p ig eon s,

rats, m onkeys, etc.) from dIverse evolutionary lineages. A s H odos and

C ~m pb ell (1 96 9) m ad e clear in a d ev astating critiq ue o f th e en tire en ter-

~ nse, o nly

re'p resen t~ tiv es of a co mm on evo lu tio nary lin eag e p ro vid e a

fIrm found~tIon for m ferences concerning the evolution of behavior.

R eprese~ tatIv es o f d iv e.rse lin eag es p ro vid e in fo rm atio n ab ou t g en eral

m ech ~m sm s o .f .ad ap tatIo n, n ot ab ou t ev olu tio nary h isto ry .

A mm al t~ ad ltIo n an d h um an cu ltu re serv e sim ilar fu nctio ns. If, as th e

present revIew suggests, anim al tradition and hum an culture are only

P rep ara tio n o f th is m an us crip t w as g re atly fa cilita te d b y fu nd s fro m th e N atu ral

S ciences and E ngineering R esearch C ou ncil o f C anad a an d the M cM aster U ni-

versity R esearch B oard. I thank M ertice C lark, M artin D aly, D oree F rag aszy,

Jurgen Lethmate, Marc Hauser, Michael Tomasello, Ann Russon, and two

anon ym ous rev iew ers for thou ghtful com men ts on earlier drafts.


10/12

17 4


T he Q u es ti on o f A nima l C u lt ur e

17 5

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