Cultural norms of exogamy and mobility shape genetic evolution of Central African hunter-gatherers
8 affiliations
- 1HUMAN ORIGINS-Cluster of Excellence for Integrative Human Origins Studies (EXC 3101), University of Tübingen, Tübingen, Germany.
- 2Evolutionary Ecology Group, Department of Zoology, University of Cambridge, Cambridge, UK.
- 3Emmanuel College, University of Cambridge, Cambridge, UK.
- 4McDonald Institute for Archaeological Research, University of Cambridge, Cambridge, UK.
- 5Human Evolutionary Ecology Group, Department of Evolutionary Anthropology, University of Zurich, Zurich, Switzerland.
- 6Marien Ngouabi University, Brazzaville, Republic of Congo.
- 7Laboratory of Anthropology, Genetics and Peopling History, Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland.
- 8iGE3 Genomics Platform, University of Geneva, Geneva, Switzerland.
Abstract
Through a hunting and gathering lifestyle, humans have managed to thrive across all terrestrial ecosystems. A key adaptive feature enabling this ecological success is the ability of hunter-gatherer societies to maintain high levels of genetic diversity despite ecological and demographic shocks, but the mechanisms underlying this resilience are poorly understood. Here, we integrate genomic, demographic, mobility, and ethnographic data from two Central African hunter-gatherer populations to show that genetic diversity emerges from interacting effects of population size, mobility, and cultural norms governing marriage. We first demonstrate direct selection against background homozygosity: Even modest increases in runs of homozygosity, in the near absence of close-kin marriages, are associated with reduced reproductive success. Despite regional differences in effective population size, clustering of relatives, sedentism, and exogamy rules, overall levels of homozygosity are similarly low in both populations. These shared genetic outcomes are achieved through distinct strategies: In one region, strict exogamy combined with high lifetime mobility limits local relatedness, whereas in the other, more relaxed exogamy norms are offset by increased male mate-search distances that reduce offspring homozygosity. Together, our results show that human populations flexibly adjust mobility and social norms to demographic constraints to preserve genetic diversity and avoid fitness costs, revealing culture as a central component of human adaptation.
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BibTeX
@article{padillaiglesias2026cultural,
title = {{Cultural norms of exogamy and mobility shape genetic evolution of Central African hunter-gatherers}},
author = {Cecilia Padilla-Iglesias and Dieudrice Nganga and Eustache Amboulou and Juliette Ruf and Pascale Gerbault and Mylène Docquier and Suspense Ifo Averti and Lucio Vinicius and Andrea Manica and Andrea Migliano},
journal = {Science Advances},
year = {2026},
month = oct,
doi = {10.1126/sciadv.aeh1658},
url = {https://www.science.org/doi/abs/10.1126/sciadv.aeh1658},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Cultural norms of exogamy and mobility shape genetic evolution of Central African hunter-gatherers
AU - Cecilia Padilla-Iglesias
AU - Dieudrice Nganga
AU - Eustache Amboulou
AU - Juliette Ruf
AU - Pascale Gerbault
AU - Mylène Docquier
AU - Suspense Ifo Averti
AU - Lucio Vinicius
AU - Andrea Manica
AU - Andrea Migliano
PY - 2026
DA - 2026/10/28
JO - Science Advances
DO - 10.1126/sciadv.aeh1658
UR - https://www.science.org/doi/abs/10.1126/sciadv.aeh1658
AB - Through a hunting and gathering lifestyle, humans have managed to thrive across all terrestrial ecosystems. A key adaptive feature enabling this ecological success is the ability of hunter-gatherer societies to maintain high levels of genetic diversity despite ecological and demographic shocks, but the mechanisms underlying this resilience are poorly understood. Here, we integrate genomic, demographic, mobility, and ethnographic data from two Central African hunter-gatherer populations to show that genetic diversity emerges from interacting effects of population size, mobility, and cultural norms governing marriage. We first demonstrate direct selection against background homozygosity: Even modest increases in runs of homozygosity, in the near absence of close-kin marriages, are associated with reduced reproductive success. Despite regional differences in effective population size, clustering of relatives, sedentism, and exogamy rules, overall levels of homozygosity are similarly low in both populations. These shared genetic outcomes are achieved through distinct strategies: In one region, strict exogamy combined with high lifetime mobility limits local relatedness, whereas in the other, more relaxed exogamy norms are offset by increased male mate-search distances that reduce offspring homozygosity. Together, our results show that human populations flexibly adjust mobility and social norms to demographic constraints to preserve genetic diversity and avoid fitness costs, revealing culture as a central component of human adaptation.
SN - 2375-2548
ER -