title: Competition for Cooperation: variability, benefits and heritability of relational wealth in hunter-gatherers.
abstract: Many defining human characteristics including theory of mind, culture and language relate to our sociality, and facilitate the formation and maintenance of cooperative relationships. Therefore, deciphering the context in which our sociality evolved is invaluable in understanding what makes us unique as a species. Much work has emphasised group-level competition, such as warfare, in moulding human cooperation and sociality. However, competition and cooperation also occur within groups; and inter-individual differences in sociality have reported fitness implications in numerous non-human taxa. Here we investigate whether differential access to cooperation (relational wealth) is likely to lead to variation in fitness at the individual level among BaYaka hunter-gatherers. Using economic gift games we find that relational wealth: a) displays individual-level variation; b) provides advantages in buffering food risk, and is positively associated with body mass index (BMI) and female fertility; c) is partially heritable. These results highlight that individual-level processes may have been fundamental in the extension of human cooperation beyond small units of related individuals, and in shaping our sociality. Additionally, the findings offer insight in to trends related to human sociality found from research in other fields such as psychology and epidemiology.
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Chaudhary
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: Gul Deniz
authors.initials: GD
authors.lastname: Salali
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Thompson
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: Aude
authors.initials: A
authors.lastname: Rey
authors.affiliation: Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom.
authors.forename: Pascale
authors.initials: P
authors.lastname: Gerbault
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: Edward Geoffrey Jedediah
authors.initials: EG
authors.lastname: Stevenson
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Dyble
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: Abigail
authors.initials: A
authors.lastname: E Page
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: Daniel
authors.initials: D
authors.lastname: Smith
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: Ruth
authors.initials: R
authors.lastname: Mace
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: Lucio
authors.initials: L
authors.lastname: Vinicius
authors.affiliation: Department of Anthropology, University College London, London WC1H 0BW, United Kingdom.
authors.forename: Andrea Bamberg
authors.initials: AB
authors.lastname: Migliano
mesh_terms: D000328:Adult; D015992:Body Mass Index; D003299:Cooperative Behavior; D005260:Female; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D008875:Middle Aged; D044382:Population Groups; D012919:Social Behavior