The evolution of large-scale cooperation in human populations.
Doctoral thesis, UCL (University College London).
Large-scale cooperation between unrelated humans is a major evolutionary puzzle. Natural selection should favour traits benefiting the self, whereas cooperation entails a cost to self to benefit another. The work presented in this thesis makes an empirical contribution towards understanding the evolution of large-scale cooperation in humans. Theory posits that large-scale cooperation evolves via selection acting on populations amongst which variation is maintained by cultural transmission. While cross-cultural variation in cooperation is taken as evidence in support of this theory, most studies confound cultural and environmental differences between populations. I test and find support for the hypothesis that variation in levels of cooperation between populations is driven by differences in demography and ecology rather than culture. I use economic games and a new ‘real-world’ measure of cooperation to demonstrate significant variation in levels of cooperation across 21 villages of the same small-scale, forager society, the Pahari Korwa of central India. Demographic factors explain part of this variation. Variation between populations of the same cultural group in this study is comparable in magnitude to that found between different cultural groups in previous studies. Experiments conducted in 14 of the villages demonstrate that the majority of individuals do not employ social learning in the context of a cooperative dilemma. Frequency of social learning varies considerably across populations; I identify demographic factors associated with the learning strategy individuals employ. My findings empirically challenge cultural group selection models of large-scale cooperation; behavioural variation driven by demographic and ecological factors is unlikely to maintain stable differences essential for selection at the population-level. This calls for re-interpretation of cross-cultural data sampled from few populations per society; behavioural variation attributed to ‘cultural norms’ may reflect environmental variation. The work presented in this thesis emphasises the central role of demography and ecology in shaping human social behaviour.
|Title:||The evolution of large-scale cooperation in human populations|
|UCL classification:||UCL > School of Arts and Social Sciences > Faculty of Social and Historical Sciences > Anthropology|
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