THE DEMOGRAPHIC-TRANSITION - ARE WE ANY CLOSER TO AN EVOLUTIONARY EXPLANATION

The radical shift in human reproduction in the late 19th century, know n as the demographic transition, constitutes a major challenge to evol utionary approaches to human behaviour. Why would people ever choose t o limit their reproduction voluntarily when, at the peak of the Indust rial Revolution, resources were apparently so plentiful? Can the trans ition be attributed to standard life history tradeoffs, is it a conseq uence of cultural evolutionary processes, or is it simply a maladaptiv e outcome of novel and environmental social conditions? Empirical anal yses and new models suggest that reproductive decision making might be driven by a human psychology designed by natural selection to maximiz e material wealth. If this is the case, the mechanisms governing ferti lity and parental investment are likely to respond to modern condition s with a fertility level much lower than that that would maximize fitn ess.