Coastal foragers and the origins of modern human behavior

Curtis W. Marean Institute of Human Origins

School of Human Evolution and Social Change Arizona State University, Tempe, AZ 85287-2402 USA

Proposal • The conditions that lead to land ownership and

defense (territoriality) in human evolution only arise when the diet expands to resources that are dense and predictable

• In Africa, this is only in coastal, lake, and riverine contexts (aquatic)

• This occurs relatively late in human evolution – After 200 thousands years ago (ka) – After the origins of modern humans – Only in the modern human lineage (not

Neanderthals or other archaic hominins)

Proposal • Why so late? Why not before 200 ka?

– Using coastal resources with sufficient productivity to trigger defense requires a complex cognition that can develop a calendar (Marean 2011)

– Using riverine or lake resources requires complex technology that:

• Needs to be driven by intensification • Requires a prolonged ratcheting process coupled

to sufficient population size to stick – So, coastal resource use appeared first (~200

ka) while riverine/lake resource appeared much later (>40 ka)

Proposal • Prior to the development of coastal

adaptations (before ~200 ka), all hominin adaptations in Africa were highly mobile, low density, and non-territorial (no active boundary defense)

• Coastal adaptations only developed in a small number of locations that were relatively geographically isolated at the time of their origins – Coastal South Africa (absolutely) – Coastal Maghreb (maybe, probably not)

Proposal • Coastal adaptations and this new territorial

system triggers inter-group conflict (~200-130 ka)

• Inter-group conflict and the small isolated population provides the ideal conditions for the origins of prosocial behaviors (following Bowles 2009; Bowles and Gintis 2011)

• Climate change at ~130 ka – Connects this isolated population to Africa – This isolated population expands bringing a

new prosocial hominin worldwide, or – The genes associated with prosociality spread

1000's of years0 100 200 300 400 500 600 700 800de

lta D

EPI

CA

Ice C

ore

-450

-400

-350

Eurasia

Africa

Warm

Cold

Eurasian Archaic Lineage

Gene Flow Very Little or No Gene Flow

First Homo sapiens fossils And genetic origin of lineage

Africans Eurasians

Denisovan

Archaic African Lineage

Melanesians Aborigines Many others

The Biological Story

Neanderthal

Modern Human Lineage

Inter-Glacial Africa 230-195 ka • Continent is warm

and wet • Well vegetated • Few natural

boundaries • Populated by a pan-

African near or fully Homo sapiens = Herto and Omo

• Gene flow widespread

Map redrawn from Adams, J.M. Global land environments since the last interglacial. http://www.esd.ornl.gov/ern/qen/nerc.html

Glacial Africa 195 - 123 ka • Continent is cool and

dry • Poorly vegetated,

widespread deserts • Many natural

boundaries • Gene flow is cut • Lineages diverge • 4 – 6 potential

progenitor lineages Map redrawn from Adams, J.M. Global land environments since the last interglacial. http://www.esd.ornl.gov/ern/qen/nerc.html

Characteristics of the Coastal Adaptation

• Mobility systems always intercept the coast, sometimes moving between the interior and the coast, and are designed to systematically intercept the coast at crucial times (or even stay there all year)

• Diet includes a substantial portion of shellfish and fish, and sometimes sea mammals and sea birds

• People embed in cultural knowledge and traditions the importance of the sea and lunar scheduling of the tides

• Schedule their activities, and sometimes ideology, around the tidal rhythms of the sea

• Often develop technological and cultural peculiarities

How do we Identify Coastal Adaptations Archaeologically?

• Isotopic identification of marine-dominated diet on human skeletal remains

• Presence of shellmidden deposits – Sediment is shell supported

• Residential mobility is scheduled around spring and neap tides

• Tidally focused shellfish collection • Indications of marine foraging embedded in

cultural institutions – Shells are collected, traded, made into ornaments – World-view is “sea-centric”

Neotropical

Holarctic

Paleotropical

AustralianCape

Antarctic

The World’s Floral Kingdoms

13B

9C

5-6

13B

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

Age

Befo

re P

rese

nt

Pinnacle Point

9C 9B

Klas

ies

Riv

er

Blom

bos D

iepk

loof

Boom

plaa

s

13B

Sibu

du

Do Early Modern Humans Have Coastal Adaptations in South

Africa?

PP13B

Are There Shell Middens? Shell midden = shell supported matrix

PP5-6

Erich Fisher

Low Neap Tide Maximum Availability Low Spring Tide Maximum Availability

Littorina Balanoid Upper Lower

Cochlear Infratidal

0

+1.5m

-1.5m Available Available Available Unavailable

(except on equinox) Available

Is There Tidally Structured Foraging For Shellfish?

Go to Coast Leave Coast Go to Coast Leave Coast

Full Moon New Moon

Tida

l Var

iatio

n Danger Zone – No Shellfish

Caution Zone – Some Shellfish

Safe Zone - High Returns on Shellfish

Tides Structure Returns and Safety (Holding Weather Conditions Constant)

Appearance of Structured Use of Inter-Tidal Zones

Age ka Cochlear Very Low spring tide

Lower Balanoid Low spring tide

Upper Balanoid Low neap tide

70-50 Klasies Klasies

Klasies Klasies Blombos

Klasies Klasies Blombos

90-70 Blombos Blombos

Klasies Blombos Blombos

Klasies Blombos Klasies Blombos

120-90 Klasies

Klasies PP13B PP9 PP13B PP9

130-120 PP13B

170-160 PP13B

Middens Appear

Is There Evidence for a “Sea-Centric” Symbolic System?

Phalium labiatum, Helmet Shell

Glycymeris connollyi , Dog Cockel

30998 62903 121439

63696 75575

Antonieta Jerardino and Curtis W. Marean. Shellfish gathering, marine palaeoecology and modern human behavior: perspectives from Cave PP13b, Pinnacle Point, South Africa. Journal of Human Evolution 59: 412-429.

~100,000 years ago

Ochre Mixing Bowls

Shell Beads 80-70 ka in North and South Africa

Blombos Cave Grottes des Pigeons

Appearance of Coastal Adaptation In South Africa

Age ka Cochlear Very Low spring tide

Lower Balanoid Low spring tide

Upper Balanoid Low neap tide

70-50 Klasies Klasies

Klasies Klasies Blombos

Klasies Klasies Blombos

90-70 Blombos Blombos

Klasies Blombos Blombos

Klasies Blombos Klasies Blombos

120-90 Klasies

Klasies PP13B PP9 PP13B PP9

130-120 PP13B

170-160 PP13B

Mid

dens

and

Sym

bolic

She

ll U

se A

ppea

r

Full Interglacial

Full Glacial

Our Problem During the Glacial ~195-135 ka

Do Neanderthals Have Coastal Adaptations in Europe?

Gibraltar

Neanderthal Coastal Adaptations Have Been Claimed

12.0

12.5

13.0

13.5

14.0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

92.0

92.5

93.0

93.5

94.0

106.0 106.5 107.0 107.5 108.0 108.5 109.0

3 m

Nor

thin

g(m

)Plan View

Nor

thin

g(m

)

Easting (m)

Vanguard

PP13B

Plotted shellfish

5.0

5.2

5.4

5.6

2 2.5 3 3.5 4 4.5 5

16.3

16.5

16.7

16.9

106 106.5 107 107.5 108 108.5 109

Vanguard

PP13BElev

atio

n(7

0cm

)

Profile View

Elev

atio

n(7

0cm

) Plotted shellfish

A

B

C

D

Neanderthals Do Not Display Coastal Adaptations

Image from www.brettcolephotography.com

Chacma Baboons, Cape Point, South Africa Burmese long-tailed macaques, Piak

Nam Yai Island, Thailand

Image from Haslam M, Gumert MD, Biro D, Carvalho S, Malaivijitnond S. 2013. Use-Wear Patterns on Wild Macaque Stone Tools Reveal Their Behavioural History. PLoS ONE 8: e72872

Impact of a Coastal Adaptation • Population size and density typically is higher

than other hunter-gatherers • Band (local group) size typically is larger than

other hunter-gatherers • Residential mobility (the number of times per

year the band moves) is reduced • Women produce protein • Shellfish are a high quality diet that provide an

excellent source of omega-3 fatty acids – Many important nutritional benefits directly related to

fertility and cognition • Territoriality is elevated and Inter-group conflict

can be common

Territoriality - when “an area is occupied more or less exclusively by an animal or group of animals by means of repulsion through overt defense or advertisement” (Wilson, 1975)

Murngin – Australian Aborigines Warner WL. 1937. A black civilization: a social study

of an Australian tribe, Gloucester, P. Smith

Many Examples of High Territoriality of Coastal Resources in Ethnographic Record

Hunter-Gatherer Territoriality and Primitive Warfare in Anthropology

• Speck FG, Eiseley LC. 1939. Significance of Hunting Territory Systems of the Algonkian in Social Theory. American Anthropologist 41: 269-80

• Heinz HJ. 1972. Territoriality among the Bushmen in general and the !ko in particular. Anthropos 67: 405-16

• Peterson N. 1975. Hunter-gatherer territoriality: the perspective from Australia. American Anthropologist 77: 53-68

• Dyson-Hudson R, Smith EA. 1978. Human territoriality: an ecological reassessment. American Anthropologist 80: 21-41

• Cashdan EA. 1983. Territorality among human foragers: ecological models and an application to four Bushmen groups. Current Anthropology 24: 47-66

• Mead M. 1940. Warfare is only an invention—not a biological necessity. Asia 40: 402-05

• Newcomb WW, Jr. 1950. A Re-Examination of the Causes of Plains Warfare. American Anthropologist 52: 317-30

• Turney-High HH, Rapoport DC. 1971. Primitive war: Its practice and concepts: University of South Carolina Press Columbia, South Carolina

• Keeley LH. 1996. War before Civilization. New York: Oxford University Press

• Gat A. 1999. The pattern of fighting in simple, small-scale, prestate societies. Journal of Anthropological Research: 563-83

• Kelly RC. 2000. Warless Societies and the Origin of War. Ann Arbor: University of Michigan Press

• Otterbein KF. 2004. How War Began. College Station, TX: Texas A & M University

Durham WH. 1976. Resource Competition and Human Aggression, Part I: A Review of Primitive War. The Quarterly Review of Biology 51: 385-415

Special Insight - Theory of Economic Defendability

Resource Density

Resource Predictability

High

Low

High Low

Weakly Territorial Strongly Territorial

Not Territorial Not Territorial

Dyson-Hudson and Smith 1978 Model

+ Must be highly ranked and/or crucial

Resource Density

Resource Predictability

High

Low

High Low

Weakly Territorial Strongly Territorial

Not Territorial Not Territorial

Dyson-Hudson and Smith 1978 Model

+ Must be highly ranked and/or crucial

What Resources in Africa are Predictable and Dense?

Limpets

Mussels

Res

ourc

e D

ensi

ty

Resource Predictability

High

Low

High Low

Weakly Territorial

Not Territorial Not Territorial

Strongly Territorial

Origins of Microlithic Technology at 71,000 Years Ago

Cover Art by Erich Fisher

Appears Worldwide By 20,000 years ago

Blade + Microlithic Technology

Microlithic typically associated with projectile (atlatl and bow) technology

Modern Humans at 71,000 Years Ago Have Advanced Projectile Weapons

• Distance • Power • Accuracy

Australian Aborigines with Atlatls - 1914

~55 ka: Modern Humans Leave Africa ~50 ka: Arrival into SW Asia and Australia

~45 ka: Arrival into Western Europe

~14 ka: Arrival into North America ~35 ka: Spread into Arctic

The Great Human Diaspora

Why Does It Commence ~60 ka?

A Hypothesized Sequence to the Cooperating Expanding Human Species

Coastal Adaptation – 160 to 120 ka

Elevated Territoriality and Conflict

Selection for Prosocial Behaviors

Intra- and Inter-Group (Tribal) Cooperation

~ 70 ka??

Complex cognition and origins of lineage – 200 to 160 ka

Out of Africa