Sharing and caring: Testosterone, fathering, and generosity among BaYaka foragers of the Congo Basin

Lee T Gettler,Mallika S Sarma,Adam H Boyette,Valchy Miegakanda,Sheina Lew-Levy

doi:10.1038/s41598-020-70958-3

Abstract

Humans are rare among mammals in exhibiting paternal care and the capacity for broad hyper-cooperation, which were likely critical to the evolutionary emergence of human life history. In humans and other species, testosterone is often a mediator of life history trade-offs between mating/competition and parenting. There is also evidence that lower testosterone men may often engage in greater prosocial behavior compared to higher testosterone men. Given the evolutionary importance of paternal care and heightened cooperation to human life history, human fathers’ testosterone may be linked to these two behavioral domains, but they have not been studied together. We conducted research among highly egalitarian Congolese BaYaka foragers and compared them with their more hierarchical Bondongo fisher-farmer neighbors. Testing whether BaYaka men’s testosterone was linked to locally-valued fathering roles, we found that fathers who were seen as better community sharers had lower testosterone than less generous men. BaYaka fathers who were better providers also tended to have lower testosterone. In both BaYaka and Bondongo communities, men in marriages with greater conflict had higher testosterone. The current findings from BaYaka fathers point to testosterone as a psychobiological correlate of cooperative behavior under ecological conditions with evolutionarily-relevant features in which mutual aid and sharing of resources help ensure survival and community health.

Highlights

Humans are rare among mammals in exhibiting paternal care and the capacity for broad hypercooperation, which were likely critical to the evolutionary emergence of human life history
In OLS regression models with clustered standard errors and adjusted for key demographic and energetic covariates, we found that BaYaka fathers who were ranked as better sharers within the community had lower T than men seen as poorer sharers (p = 0.005; Table 3; Fig. 1)
We found that BaYaka fathers who were seen as better community sharers and those in less conflicted marriages, respectively, had lower T than their peers

Summary

Introduction

Humans are rare among mammals in exhibiting paternal care and the capacity for broad hypercooperation, which were likely critical to the evolutionary emergence of human life history. During periods when males partner with females to raise young, their T often declines, which helps divert limited time and energetic resources towards that cooperative parenting effort and away from competition[3,4,5,6] In such species, T has the potential to shape variation between males in health, survival, and reproductive fitness. Lower T in fathers to greater paternal care has been conducted in the U.S, Europe, and the Philippines, which are cultural contexts in which care within the nuclear family has long been primarily prioritized or is increasingly emphasized (Philippines)[21,22,23,24,25] In these societies, communal caregiving (or “cooperative breeding”), which is widely recognized as a critical adaptation that helped facilitate the evolution of human’s “slow” life history, is variably practiced[26,27,28,29]

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Discussion

Conclusion