Darwin-L Message Log 8:74 (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.

<8:74>From LANGDON@GANDLF.UINDY.EDU  Fri Apr 22 08:41:24 1994

Date: Fri, 22 Apr 1994 08:41:24 -0500
To: darwin-l@ukanaix.cc.ukans.edu
Subject: Re: chimps & sex

 Patricia Princehouse writes

> I'm no great fan of sociobiology but am intrigued by the
> sociobiological/adaptive argument for bonobo sexual behavior - that the
> high level of sexual activity is not directly related to the reproductive
> benefits of competing individuals but that benefits of greater group
> coherence promote selection for the genes responsible for these behaviors.
> I don't remember if Meredith said anything about it in the article but
> I've heard numerous times in conversation (eg at anth meetings) that the
> bonobo example helps explain human penis size as the result of sexual
> selection (ie evidently bonobos have larger penises than common chimps and
> use them as visual cues in displays for initiating sexual activity & use
> many visual displays, often hand signals, mostly having to do with food &
> sex).

Wrangham reviews non-conceptive sexual behavior in chimps and other
species in Human Nature 4(1993):47-79, "The evolution of sexuality
in chimpanzees and bonobos."

There are several reasons for non-conceptive sex-- group coherence,
reassurance, elevation in status by associating with high status
individuals, food and other material gain. There are sufficient
individual benefits that its evolution seems reasonable, though
one ultimately has to address the question why it occurs more in
some species than others.

I think this is completely unrelated to penis size. The latter
probably reflects the distance to the cervix. Goodall reports male
common chimps occasionally displaying an erect penis to females in
an apparent attempt to solicit sex. Is there any documentation for
similar behavior in bonobos? If females respond, is there any
reasons to believe that they would do so on the basis of size
rather than merely the erect state?

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