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. 2019 Nov;3(11):1154-1163.
doi: 10.1038/s41562-019-0679-2. Epub 2019 Aug 12.

Testing Adaptive Hypotheses of Alloparenting in Agta Foragers

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Free PMC article

Testing Adaptive Hypotheses of Alloparenting in Agta Foragers

Abigail E Page et al. Nat Hum Behav. .
Free PMC article

Abstract

Human children are frequently cared for by non-parental caregivers (alloparents), yet few studies have conducted systematic alternative hypothesis tests of why alloparents help. Here we explore whether predictions from kin selection, reciprocity, learning-to-mother and costly signalling hypotheses explain non-parental childcare among Agta hunter-gatherers from the Philippines. To test these hypotheses, we used high-resolution proximity data from 1,701 child-alloparent dyads. Our results indicated that reciprocity and relatedness were positively associated with the number of interactions with a child (our proxy for childcare). Need appeared more influential in close kin, suggesting indirect benefits, while reciprocity proved to be a stronger influence in non-kin, pointing to direct benefits. However, despite shared genes, close and distant kin interactions were also contingent on reciprocity. Compared with other apes, humans are unique in rapidly producing energetically demanding offspring. Our results suggest that the support that mothers require is met through support based on kinship and reciprocity.

Conflict of interest statement

Competing interests

The authors declare no competing interests.

Figures

Figure 1
Figure 1. Predictors of carer-child interactions.
Odd ratios with 95% CI for each of the predictor variables in the univariable mixed-effect models (triangles) and the full mixed-effect models between and within households (circles; n = 1,701) and the full mixed-effect models between households only (squares; n = 1,615). Bars represent 95% confidence intervals, bars spanning the 0 line are non-significant.
Figure 2
Figure 2. Relatedness, need and reciprocity and carer-child interactions.
Model predicted number of contacts based on interactions between kin type and a) receiver household need; b) household reciprocity. Red lines are close kin (r = 0.5), green lines distant kin (0 ≤ r ≤ 0.25) and non-kin (r = 0) are represented by blue lines. Shaded zones represent 95% confidence intervals

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