Darwin-L Message Log 8:43 (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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<8:43>From LANGDON@GANDLF.UINDY.EDU  Thu Apr 14 12:29:12 1994

Date: Thu, 14 Apr 1994 12:29:12 -0500
From: "JOHN LANGDON"  <LANGDON@GANDLF.UINDY.EDU>
To: darwin-l@ukanaix.cc.ukans.edu
Subject: Re: sexual selection

I thank the many people who have responded to my query about sexual selection
on and off the net. In fact, I have had so many replies that I fear I cannot
make personal response to all. They have been helpful in focusing my thinking
and some tackle some of the specific issues I an trying to address. I have seen
several restatements of the standard lines. I accept the theory but have qualms
about applying it to humans.

Bonnie Blackwell replies...
> >but what about warfare as a method of selecting males in the middle ages.

to which James Maclaurin replies . . .
> I agree with Blackwell that this is a case of Male competition (in some
> sense of competition) but whether or not it counts as an important case of
> sexual selection depends on several factors.

In addition to Maclaurin's critique of this, I add, what is the relationship
between such combat and mating? If losers lost simply because they were dead,
this is natural selection. It becomes sexual selection only if one can relate
it to mating preferences.

Likewise, Wright's response that we can expect males to have greater variance
in RS is reasonable. But his previous statement "the evidence suggests that
sexual selection has been more intense among men" does not automatically
follow, however many times I see it in print. High variance in RS among males
does not equal sexual selection, although it is a necessary condition.

What is the evidence that sexual selection of males has been an important force
shaping human evolution since the ape-human split? Dimorphism of body size has
diminished several times (continually?) since the Miocene. Evidence for sperm
competition is ambiguous, at best. About the only striking acquisitions of
human males that are likely to be explained by sexual selection have been (1)
beards and (2) a tendency to invest in long term pair-bonds. The second is a
significant change that appears to have come about in both sexes, but it
negates the argument that contemporary male competition centers on promiscuity.

In a very skeptical mood, how can we be certain that male behavior is not
simply a carry-over of proximate behaviors evolved in the Miocene that no
longer have evolutionary significance now that pair-bonding has become so much
more important?

Let me put it another way, and this is a challenge to all of human
sociobiology. Given that (1) the human brain has evolved a capacity for a great
range of behavior; and (2) that range includes making rational decisions in our
own best interest, when do we ascribe an apparently sensible behavior as an
adaptive evolved trait and when is it a non-evolved economic decision? A great
deal of promiscuous behavior can be explained as non-evolved pursuit of sexual
behavior (specific examples from the literature-- soliciting prostitutes and
masturbation). What are the grounds for arguing that these are evolved
reproductive strategies?

JOHN H. LANGDON                email   LANGDON@GANDLF.UINDY.EDU
DEPARTMENT OF BIOLOGY          FAX  (317) 788-3569
UNIVERSITY OF INDIANAPOLIS     PHONE (317) 788-3447
INDIANAPOLIS, IN 46227

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