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Impact of infancy duration on adult size in 22 subsistence‐based societies
Author(s) -
Gawlik Aneta,
Walker Robert S,
Hochberg Ze’ev
Publication year - 2011
Publication title -
acta paediatrica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 115
eISSN - 1651-2227
pISSN - 0803-5253
DOI - 10.1111/j.1651-2227.2011.02395.x
Subject(s) - breastfeeding , demography , natural fertility , medicine , fertility , subsistence agriculture , weaning , breast feeding , trait , population , birth weight , pregnancy , pediatrics , geography , environmental health , agriculture , biology , endocrinology , family planning , research methodology , sociology , computer science , programming language , genetics , archaeology
Aim: Humans evolved to withstand harsh environments by adaptively decreasing their body size. Thus, adaptation to a hostile environment defers the infancy‐childhood transition age (ICT), culminating in short stature. In natural‐fertility human societies, this transition is associated with weaning from breastfeeding and the mother’s new pregnancy. We therefore used the interbirth interval (IBI) as a surrogate for the ICT. Methods: We hypothesized that long IBI will be associated with smaller body size. The sample used is 22 subsistence‐based societies of foragers, horticulturalists and pastorals from Africa, South America, Australia and Southeast Asia. Results: The IBI correlated negatively with the average adult bodyweight but not height. After correction for ‘pubertal spurt takeoff’ and ‘weight at age 5’, the IBI explains 81% of ‘average adult weight’ variability. Conclusions: This inter‐population study confirms that body weight is adaptively smaller in hostile environments and suggests that the selected trait for this adaptation is the ICT age.