Gift games among saami pastoralists
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Transcript of Gift games among saami pastoralists
Gift games among Saami pastoralists show group membership can be more
important than genetic kinship
Matthew G. ThomasBård-Jørgen Bårdsen
Marius Warg NæssRuth Mace
Cooperative herding- sharing, defending, loaning, exchanging
- lowest cost strategy
- pooling risk
- presence of relatives associated with increased herd size
Cooperation influenced by mix of genetic (kin selection)and social factors (reciprocity)
Aktipis et al. 2011; Apicella et al. 2012; Gerkey 2013; Lamba & Mace 2011; Næss et al. 2010
Who do herders help?
What makes people more likely to receive gifts?
Hypotheses:
Genetic kinship > cultural kinship gifts to relatives
Cultural kinship > genetic kinship gifts to cooperative group
Wealth flows: gifts given to younger family members
Kaplan 1994; Hamilton 1964; Trivers 1971
Study site: Finnmark, Norway
~3,500 Saami reindeer herders
533 license owners
(75 in study district)
Households form cooperative groups: the siida
Summer siidas contain from 10 to 100+ people
Summer siidas split into smaller, family-oriented winter siidas
70°
65°
60°
20°10°
100 km
From Næss (2009)
Interviewed 30 (out of 75) licensed herd owners in a district
Externally valid, culturally salient experimental game: anonymous gifts of petrol
Assembled complete kinship network for district
Methods
Gift network
Colours are siidas
Circles = 75 license owners(Size is no. gifts received)
Filled circle = 30 interviewees
Gift network: 71 gifts given. 45 given within siida.
Colours are siidas
Circles = 75 license owners(Size is no. gifts received)
Filled circle = 30 interviewees
Lines = gifts(Thickness is gift size)
Same siida? Related?Gift?
Yes No
YesYes 30 74
No 15 153
NoYes 3 88
No 23 1,834
Breakdown of gifts:Highest proportion given to kin in same siida
Total of 2,220 potential giftsgiven from 30 interviewees
to any of 75 people
Yes
No
Yes
No
Yes
No
Yes
No
Most of the 23 gifts to non-kin in other siidas are for ‘good’ or new herders
Good herders: 8
Young/new owners: 5
Current or future reciprocity: 2
Old friend: 1
Need help: 1
Lazy: 3
Family: 2
(No reason given): 1
Siida membership is strongest predictor of receiving a gift
(the best model)
Model Predictors Odds ratio p value ΔAIC
Close family onlyMember of same summer siida? (ref: no) 24.29 0.004
0.000Close family ( )? (ref: no) 6.05 0.24
All relativesMember of same summer siida? (ref: no) 19.11 <0.001
1.006Genetic relative ( )? (ref: no) 4.66 0.068
Gifts not preferentially given to younger family
Gifts to kin Gifts to non-kin
to youngerherders
to olderherders
to youngerherders
to olderherders
Siida membership makes people more likely to receive gifts
Hypotheses:
Genetic kinship > cultural kinship gifts to relatives
Cultural kinship > genetic kinship gifts to cooperative group
Wealth flows: gifts not given to younger family members
Belonging to the same siida is strongest predictor of receiving gifts
But gifts given to non-kin in other siidas- reputation and reciprocity
No age bias in gift giving
Studies of cooperation to understand high reindeer death rate
Summary
Ruth MaceAndrea MiglianoHuman Evolution Ecology Group at UCL
Katharina OlsenJon Mikkel EiraThe herders of Finnmark
ERCFramsenteretNorsk Institutt for NaturforskningCICERO
Thanks
ReferencesAktipis, C. A., Cronk, L., & Aguiar, R. (2011). Risk-Pooling and Herd Survival: An Agent-Based Model of a Maasai Gift-Giving System. Human Ecology, 39, 131–140
Apicella, C. L., Marlowe, F. W., Fowler, J. H., & Christakis, N. A. (2012). Social networks and cooperation in hunter-gatherers. Nature, 481, 497–501
Gerkey, D. (2013). Cooperation in context: Public goods games and post-Soviet collectives in Kamchatka, Russia. Current Anthropology, 54, 144–176
Lamba, S., & Mace, R. (2011). Demography and ecology drive variation in cooperation across human populations. Proceedings of the National Academy of Sciences of the United States of America, 108, 14426–30
Næss, M. W., Bårdsen, B.-J., Fauchald, P., & Tveraa, T. (2010). Cooperative pastoral production — the importance of kinship. Evolution and Human Behavior, 31, 246–258
Ohtsuki, H., Hauert, C., Lieberman, E., & Nowak, M. A. (2006). A simple rule for the evolution of cooperation on graphs and social networks. Nature, 441, 502–5
Trivers, R. (1971). The evolution of reciprocal altruism. Quarterly Review of Biology, 46, 35–57
West, S. A., Griffin, A. S., & Gardner, A. (2007). Evolutionary explanations for cooperation. Current Biology, 17, R661–72