Quality-quantity trade-off of human offspring under adverse environmental conditions
Meij, J.J.; van Bodegom, D.; Ziem, J.B.; Amankwa, J.; Polderman, A.M.; Kirkwood, T.B.L.; de Craen, A.J.M.; Zwaan, B.J.; Westendorp, R.G.J.
Journal of Evolutionary Biology 22(5): 1014-1023
2009
ISSN/ISBN: 1420-9101 PMID: 19298492 DOI: 10.1111/j.1420-9101.2009.01713.xDocument Number: 223797
A central paradigm in life-history theory is the trade-off between offspring number and quality. Several studies have investigated this trade-off in humans, but data are inconclusive, perhaps because prosperous socio-cultural factors mask the trade-off. Therefore, we studied 2461 offspring groups in an area under adverse conditions in northern Ghana with high fertility and mortality rates. In a linear mixed model controlling for differences in age and tribe of the mother and socioeconomic status, each additional child in the offspring group resulted in a 2.3% (95% CI 1.9-2.6%, P < 0.001) lower proportional survival of the offspring. Furthermore, we made use of the polygamous population structure and compared offspring of co-wives in 388 households, thus controlling for variation in resources between compounds. Here, offspring survival decreased 2.8% (95% CI 2.3-4.0%, P < 0.001) for each increase in offspring number. We interpret these data as an apparent quality-quantity trade-off in human offspring.
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