Monday, January 26, 2009

Evolutionary roots of human behaviour / gender pay gap

The year-end issue of the Economist offered an overview of some recent work in the burgeoning field of evolutionary social science, i.e. the inquiry into possible evolutionary roots of human social, economic, and political behaviour. The article is titled "Why we are, as we are", and primarily reviews studies that highlight "Darwinian answers to social questions", i.e. different ways in which the evolutionary drive to reproduce may translate into observed patterns of human behaviour. The article is interesting though also a bit simplistic.

One of the more interesting and counter-intuitive findings: the number of children a man fathers is, on average, correlated with his income. It is important to note, however, that this relationship is drowned out by the impact of education (i.e. it only holds if one controls for education, which is highly correlated with income but tends to reduce reproduction). The apocalyptic scenario laid out in the movie Idiocracy may, therefore, still come true :-)

More importantly (and problematically), as my favourite evolutionary biologist points out: most of the findings discussed in the article lean rather heavily on the assumption that "correlation probably implies causation". For example, the article suggests that the growing income gap between men and women as they get older may be related to the fact that older women feel less of a need to show off to catch a mate, and may care more about security and working conditions. Fair enough, this may be part of the explanation. But the fact that women may care more about security does not mean they are not experiencing gender-based discrimination in the workplace.

After all, this particular "finding" downplays the fact that there have been dramatic reductions (in some places and among some groups) in the gender pay gap over the past century. This is hardly long enough for meaningful evolutionary change among humans on this issue, leaving discrimination as the rather more obvious explanation. To hint that all (or even most) of the remaining gap is evolutionarily determined seems willfully (even disingenuously) naive.

In fairness, it is worth noting that the actual report on which the Economist relies to sustain its argument (available here) does not rely on evolutionary claims, nor does it say that no pay gap exists. It mostly argues
1) that the gap is smaller than it appears in aggregate data because men and women are not evenly distributed across all types of jobs (and part of that difference is by choice), and
2) that, as a result, one-size-fits-all policies aimed at redressing the gap will probably fail.

Both of these claims are uncontroversial. Unfortunately, both the report's author and those who have cited it seem inclined to gloss over two important points:
1) A gap that is smaller than it might seem at first sight (and shrinking) may still be sizeable and, for those on the "receiving" end of the gap, of great importance.
2) Narrowly targeted policies aimed at overcoming gender discrimination within particular economic sectors may well succeed (and, hence, are worth trying)

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