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The life-history trade-off between fertility and child survival - can we address family planning without attention to infectious diseases?
+ Author Affiliations
- ↵*Author for correspondence (d.lawson@ucl.ac.uk).
Abstract
Evolutionary models of human reproduction argue that variation in fertility can be understood as the local optimization of a life-history trade-off between offspring quantity and ‘quality’. Child survival is a fundamental dimension of quality in these models as early-life mortality represents a crucial selective bottleneck in human evolution. This perspective is well-rehearsed, but current literature presents mixed evidence for a trade-off between fertility and child survival, and little empirical ground to evaluate how socioecological and individual characteristics influence the benefits of fertility limitation. By compiling demographic survey data, we demonstrate robust negative relationships between fertility and child survival across 27 sub-Saharan African countries. Our analyses suggest this relationship is primarily accounted for by offspring competition for parental investment, rather than by reverse causal mechanisms. We also find that the trade-off increases in relative magnitude as national mortality declines and maternal somatic (height) and extrasomatic (education) capital increase. This supports the idea that socioeconomic development, and associated reductions in extrinsic child mortality, favour reduced fertility by increasing the relative returns to parental investment. Observed fertility, however, falls considerably short of predicted optima for maximizing total offspring survivorship, strongly suggesting that additional unmeasured costs of reproduction ultimately constrain the evolution of human family size....
"two-thirds of child deaths in the developing world are
caused by infectious diseases such as malaria, pneumonia
and diarrhoea, difficult to prevent in the absence of
modern sanitation and medical care [44]. Under such
conditions, limiting fertility as a strategy to increase
levels of parental investment is more likely to be reduce
reproductive success."
caused by infectious diseases such as malaria, pneumonia
and diarrhoea, difficult to prevent in the absence of
modern sanitation and medical care [44]. Under such
conditions, limiting fertility as a strategy to increase
levels of parental investment is more likely to be reduce
reproductive success."
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