Saturday, February 25, 2017

Networks and cumulative culture among hunter-gatherers

Characterization of hunter-gatherer networks and implications for cumulative culture,
A. B. Migliano, A. E. Page, J. Gómez-Gardeñes, G. D. Salali, S. Viguier, M. Dyble, J. Thompson, Nikhill Chaudhary, D. Smith, J. Strods, R. Mace, M. G. Thomas, V. Latora & L. Vinicius
Nature Human Behaviour 1, Article number: 0043 (2017)

Social networks in modern societies are highly structured, usually involving frequent contact with a small number of unrelated ‘friends’. However, contact network structures in traditional small-scale societies, especially hunter-gatherers, are poorly characterized. We developed a portable wireless sensing technology (motes) to study within-camp proximity networks among Agta and BaYaka hunter-gatherers in fine detail. We show that hunter-gatherer social networks exhibit signs of increased efficiency for potential information exchange. Increased network efficiency is achieved through investment in a few strong links among non-kin ‘friends’ connecting unrelated families. We show that interactions with non-kin appear in childhood, creating opportunities for collaboration and cultural exchange beyond family at early ages. We also show that strong friendships are more important than family ties in predicting levels of shared knowledge among individuals. We hypothesize that efficient transmission of cumulative culture may have shaped human social networks and contributed to our tendency to extend networks beyond kin and form strong non-kin ties.

We studied in-camp proximity networks (within and between households) as a proxy for social interactions in two hunter-gatherer populations from Africa and southeast Asia. We developed a portable wireless sensing technology (motes; Fig. 1) to record all dyadic interactions within a radius of approximately 3 metres at 2-minute intervals for 15 hours a day (05:00–20:00) over a week, in six Agta camps in the Philippines (200 individuals, 7,210 recorded dyadic interactions) and three BaYaka camps in Congo-Brazzaville (132 individuals, 3,397 dyadic interactions; see Supplementary Table 1 with descriptive statistics for all camp networks). We built high-resolution proximity networks mapping the totality of close-range interactions within each camp. In hunter-gatherers (who lack technology-aided communication), close proximity is an indicator of joint activities such as foraging, parental care and information exchange.

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