The demographic transition: are we any closer to an evolutionary explanation?
The radical shift in human reproduction in the late 19th century, known as the demographic transition, constitutes a major challenge to evolutionary approaches to human behaviour. Why would people ever choose to limit their reproduction voluntarily when, at the peak of the Industrial Revolution, resources were apparently so plentiful? Can the transition be attributed to standard life history tradeoffs, is it a consequence of cultural evolutionary processes, or is it simply a maladaptive outcome of novel and environmental social conditions? Empirical analyses and new models suggest that reproductive decision making might be driven by a human psychology designed by natural selection to maximize material wealth. If this is the case, the mechanisms governing fertility and parental investment are likely to respond to modern conditions with a fertility level much lower than that that would maximize fitness.
Dept of Anthropology, University of California at Davis, Davis, CA 95616, USA.
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Borgerhoff Mulder