Sex equality can explain the unique social structure of hunter-gatherer bands

Abstract

The social organization of mobile hunter-gatherers has several derived features, including low within-camp relatedness and fluid meta-groups. Although these features have been proposed to have provided the selective context for the evolution of human hypercooperation and cumulative culture, how such a distinctive social system may have emerged remains unclear. We present an agent-based model suggesting that, even if all individuals in a community seek to live with as many kin as possible, within-camp relatedness is reduced if men and women have equal influence in selecting camp members. Our model closely approximates observed patterns of co-residence among Agta and Mbendjele BaYaka hunter-gatherers. Our results suggest that pair-bonding and increased sex egalitarianism in human evolutionary history may have had a transformative effect on human social organization.

Reproductive trade-offs in extant hunter-gatherers suggest adaptive mechanism for the Neolithic expansion

“…There are around 1,000 Agta living in Palanan municipality, Isabela Province, located in northeastern Luzon, Philippines. The Agta are primarily fisher-foragers, residing either at the coast or in inland watersheds (91). Hunting does occur, but fishing is far more common: of 2,168 work activities 54% were spent fishing, 20% in gathering, and 3% hunting.…”

The Original Partnership Societies: Evolved Propensities for Equality, Prosociality, and Peace

“…One indicator of the gender egalitarian nature of nomadic forager social organization is that bilateral descent is typical, meaning that lines of descent are equally reckoned through both parental lines, as opposed to favoring, for instance, patrilineal descent. Recent research also shows the rough equality between men and women regarding residency decisions (Dyble et al, 2015;Fry, 2006;Knauft, 1991).…”

“…For example, Nowak (2011) recently dubs human beings "supercooperators" and reviews multiple lines of evidence as to why cooperation actually represents the centerpiece on the human evolutionary table (see also Dyble et al, 2015). Obviously, humans possess the capacity for competition, cruelty, and violence, but a growing corpus of evidence shows that human nature is much less violent and selfish than has long been presumed under the traditional evolutionary paradigm (de Waal, 2009;Ferguson, 2011;Fry, 2006;Hart & Sussman, 2009Nowak, 2011).…”

“…4 http://pubs.lib.umn.edu/ijps/vol4/iss1/4 that is regularly described for nomadic foragers. Uniformly, mobile foragers share meat (e.g., Apicella et al, 2012;Birdsell, 1971;Boehm, 1999;Clastres, 1972;Dyble et al, 2015;Fry, 2006 and references therein;Gusinde, 1937;Knauft, 1991;Leacock, 1954;Lee, 1993). For instance, the Guayaki of South America possess a food taboo that promotes meat-sharing: A man should not consume the meat of any animals he personally has killed (Clastres, 1972, p. 169).…”

“…The fluctuating nature of band composition also can tilt decisions toward reciprocal sharing instead of toward hostile competition over resources (Fry & Söderberg, 2013b; see also Fry, 2006;Myers, 1982). Dyble et al (2015) speculate that over the course of human evolution, "co-residence with unrelated individuals set the selection environment for the evolution of hypercooperation and prosociality. …This social system may have allowed hunter-gatherers to extend their social networks, buffering environmental risk and promoting levels of information exchange required for cumulative culture" (p. 798).…”