Infant allocare in traditional societies

Publication date: 1 September 2018Source: Physiology & Behavior, Volume 193, Part AAuthor(s): Karen L. Kramer, Amanda VeileAbstractAcross human societies infants receive care from both their mothers and others. Reproductive cooperation raises two important questions: how does allocare benefit mothers and infants, and why do caretakers help mothers when they could spend their time in other, perhaps more valuable ways? We use behavioral and biological data from three small-scale societies to evaluate 1) how allocare affects a nursing mother's time, 2) whether a mother's birth interval length, surviving fertility and infant weight vary as a function of the childcare help that she receives, and 3) the opportunity cost for helpers to spend time caring for children. Across our hunter-gatherer and agricultural samples we find that on average mothers provide 57% of the direct care that an infant receives and allocaretakers 43% (±20%). Model results show that for every 10% increase in allocare the probability that a mother engages in direct care diminishes by 25%, a potential savings of an estimated 165 kcals per day. While allocare has a significant immediate impact on mother's time, no detectable effect on delayed fitness measures (birth interval and surviving fertility) or on infant weight status was evident. Cross culturally we find that other than mothers, siblings spend the most time caretaking infants, and they do so without compromising the time that they might otherwise sp...
Source: Physiology and Behavior - Category: Physiology Source Type: research