Darwin-L Message Log 8:38 (April 1994)

Academic Discussion on the History and Theory of the Historical Sciences

This is one message from the Archives of Darwin-L (1993–1997), a professional discussion group on the history and theory of the historical sciences.

Note: Additional publications on evolution and the historical sciences by the Darwin-L list owner are available on SSRN.

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<8:38>From wright@clark.net  Thu Apr 14 01:09:11 1994

Date: Thu, 14 Apr 1994 02:09:21 -0400 (EDT)
From: Bob Wright <wright@clark.net>
Subject: Re: sexual selection
To: darwin-l@ukanaix.cc.ukans.edu

JOHN LANGDON writes, about sexual selection in humans:

> Are these scenerios mutually contradictory or can each sex select the other
> simultaneously?

I believe that sexual selection can indeed work in both directions
simultaneously--men competing for women and women competing for men. But
the evidence suggests that sexual selection has been more intense among
men. A key index of that intensity is the variation in reproductive
success within a given sex.  Since men can in principle have many
offspring per year, whereas women can't, that variation is potentially
much larger among men. And the anthropological record suggests that,
indeed, most societies, including many that seem roughly typical of the
social environment in which much human evolution took place, have been at
least mildly polygynous; some men have succeeded in monopolizing more than
one mate and producing many offspring, at the expense of other men who
were therefore left with no mate and no offspring. This is the driving
force behind sexual selection, and it is hard to imagine it reaching
comparable heights among females; virtually any young woman, after all,
can secure a mate for long enough to achieve reproduction.

> Females
> are now competing with one another because males are investing more.

The advent of male parental investment can indeed intensify competition
among females, and it presumably has in our species. Though, as I've
noted, just about any fertile woman can arrange to have offspring (thus
escaping the fate that afflicts a man who fails in the mating game),
having offspring who are well taken care of is another matter altogether.
This fact would seem to fuel sexual selection among women.  But again:
even given this source of competition, reproductive variation among men
seems to have fairly consistently been higher than among women, suggesting
that sexual selection has generally operated more strongly among men.

Bob Wright
Washington, DC

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