Comparative study of reproductive skew and pair-bond stability using genealogies from 80 small-scale human societies

Ryan M. Ellsworth, Mary K. Shenk, Drew H. Bailey, Robert S. Walker

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Objectives: Genealogies contain information on the prevalence of different sibling types that result from past reproductive behavior. Full sibling sets stem from stable monogamy, paternal half siblings primarily indicate male reproductive skew, and maternal half siblings reflect unstable pair bonds. Methods: Full and half sibling types are calculated for a total of 61,181 siblings from published genealogies for 80 small-scale societies, including foragers, horticulturalists, agriculturalists, and pastoralists from around the world. Results: Most siblings are full (61%) followed by paternal half siblings (27%) and maternal half siblings (13%). Paternal half siblings are positively correlated with more polygynous marriages, higher at low latitudes, and slightly higher in nonforagers, Maternal half sibling fractions are slightly higher at low latitudes but do not vary with subsistence. Partible paternity societies in Amazonia have more paternal half siblings indicating higher male reproductive skew. Conclusions: Sibling counts from genealogies provide a convenient method to simultaneously investigate the reproductive skew and pair-bond stability dimensions of human mating systems cross-culturally.

Original languageEnglish (US)
Pages (from-to)335-342
Number of pages8
JournalAmerican Journal of Human Biology
Issue number3
StatePublished - May 1 2016

All Science Journal Classification (ASJC) codes

  • Anatomy
  • Ecology, Evolution, Behavior and Systematics
  • Anthropology
  • Genetics


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