Adult sex ratios and partner scarcity among hunter-gatherers: implications for dispersal patterns and the evolution of human sociality.

ABSTRACT: Small populations are susceptible to high genetic loads and random fluctuations in birth and death rates. While these selective forces can adversely affect their viability, small populations persist across taxa. Here, we investigate the resilience of small groups to demographic uncertainty, and specifically to fluctuations in adult sex ratio (ASR), partner availability and dispersal patterns. Using 25 years of demographic data for two Savannah Pumé groups of South American hunter-gatherers, we show that in small human populations: (i) ASRs fluctuate substantially from year to year, but do not consistently trend in a sex-biased direction; (ii) the primary driver of local variation in partner availability is stochasticity in the sex ratio at maturity; and (iii) dispersal outside of the group

SUBMITTER: Kramer KL 

PROVIDER: S-EPMC5540858 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature