Shakti Lamba, October 18
Human Evolutionary Ecology Group, Department of Anthropology, University College London
The evolution of large-scale cooperation in humans
Large-scale cooperation between unrelated humans is a major evolutionary puzzle. Current theory posits that such cooperation evolved via group-level selection acting on populations amongst which variation is maintained by cultural transmission. Critically, selection can occur at the group-level only if stable behavioural variation is maintained between populations in the face of migration. 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 will present results from a study testing whether variation in levels of cooperation between populations is driven by differences in demography and ecology rather than culture.
I use ultimatum games, public goods games and a new naturalistic measure of behaviour 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.
These findings call for re-interpretation of cross-cultural data sampled from few populations per society; behavioural variation attributed to ‘cultural norms’ may reflect environmental variation. I argue that the findings present an empirical challenge to cultural group selection models of large-scale cooperation.
- Where and when:
15:45-17:00 Oct 18, 2011MPI Nijmegen, Conference room 163