Re: Zihlman and Sociobiology

Bryant (
24 Sep 1996 11:41:19 -0600

In article <528s6f$>, Susan <> wrote:
>essentially passive. While noting the idea of female choice, there is
>still an assumption that if males mate, then males reproduce, discounting
>the possibility that female action may have an impact.

There is only the assumption that males who mate have a greater
probability of reproducing than those who do not. This seems a
reasonable assumption to me. :)

>controversial example discussed before here, there is the assumption that
>a woman who is raped and becomes pregnant will automatically carry the
>child to term, thus making this an effective male reproductive strategy.

I see no such assumption. In fact, the Thornhills arrived at their study
of male coercive sexuality by way of their studies of post-rape
psychological pain in victims.

On the other hand, even in the current environment, human rapes leads to
viable pregnancies, no? I'm not sure what the point is, here. Do you
think rape was unknown in ancestral hominid populations?

> But if the rape is seen as a violent social act, and the woman
>encouraged to abort the child (something which is typically supported by
>laws which except abortion in the case of rape or incest), then it is a
>lousy strategy. So considering rape as simply a male reproductive
>strategy, outside of its social context and discounting possible female
>responses, is reductionistic.

I'm unfamiliar with how you're using "reductionistic" here.

At any rate, the Thornhills' argument was precisely the opposite. Rape
provided benefits in the form of reproductive fitness to some males, they
argue, and this caused the evolution of female counter-strategies.

A more convincing example of female counter-strategy to coercive male
suitors is the water skipper's anti-rape "atl atl" structure, with which
females fling undesired mates from their backs.

>Interestingly, Zihlman discusses the difficulties of determining
>paternity in other kinds of primate groups in the field. There is the
>assumption that observers are witnessing all matings, even though both
>males and females have been observed "sneaking" away from the main group
>to mate, outside the view of dominant males.

Nice point. Junglefowl hens do something similar, perhaps to inspire
sperm competition (?) But the vast majority of the hens' offspring are
sired by socially dominant males. It sounds like this is less clear with
non-human primates.

A recent review in Trends in Ecology and Evolution, showing that some
passarine bird females' preference for males with more complex songs
leads to differential survivorship in resulting offspring, says that DNA
evidence for EPC (extra pair copulations) in these little birds only
accounts for ~3% of the chicks hatched. That's much lower than the
cuckoldry rate for humans, I believe.