Path: utzoo!mnetor!uunet!husc6!mailrus!ames!pasteur!ucbvax!agate!saturn!chromo!kevin
From: kevin@chromo.ucsc.edu (Kevin McLoughlin)
Newsgroups: sci.bio
Subject: Re: Sexual selection
Message-ID: <2534@saturn.ucsc.edu>
Date: 28 Mar 88 20:09:10 GMT
References: <1566@mmm.UUCP> <3138@arthur.cs.purdue.edu> <1164@microsoft.UUCP> <25746@cca.CCA.COM> <1805@ssc-vax.UUCP>
Sender: usenet@saturn.ucsc.edu
Reply-To: kevin@chromo.UUCP (Kevin McLoughlin)
Organization: Physics Asylum, University of California, Santa Cruz
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>In article <25746@cca.CCA.COM>, g-rh@cca.CCA.COM (Richard Harter) writes:
>> In article <4368@blia.BLI.COM> heather@blia.BLI.COM (Heather Mackinnon) writes:
>> >There have been many human societies with baboon-style alpha male
>> >mating patterns.  [Examples of polygamy deleted.]
>> 	Not the same thing.  Human polygamy is tied to support.  The
>> male with several wives must be able to support them all.  In these
>> societies I believe you will find that polygamy was pretty much restricted
>> to a relatively wealthy minority, with most people being monogamous.

>> >This leads to an interesting question:  when did the move towards monogamy
>> >happen and why?  Did it happen when agriculture replaced hunting and 
>> >gathering?  Did it happen with the growth of cities?  

Based on my knowledge of hominid evolution, prehistoric evidence,
and known human societies (i.e. some graduate work in this field), 
my guess is that what's key here is not monogamy or polygamy per se, but
thinking about rigid pairing and the institution of marriage itself,
and humans evolving to get smart enough to map out their own kinship
on a symbolic basis, ie caring about paternity and such. I suspect it
also might have something to do with a shift from egalitarian groups,
centrally organized around females and their children and sisters 
and male consorts, to power lodged with males. And my pet theory
has for some time located this during some ice age, perhaps around
the Homo sapiens emergence period ~ 40-30,000 BP. Why? Because during
most of hominid evolution, females probably provided the bulk and
the most dependable source of food, via gathering vegetable foods
and small animals for protein. A female didn't HAVE to have a male
around (sure, it helped, but she could make it with a little help
from her friends/sisters/aunts). During the colder periods in the
temperate latitudes, however, these plant foods weren't available
for most of the year and women would have had to depend on males
to hunt bigger animals for food (the main reason women couldn't
do this heavy-duty hunting work: they were pregnant or nursing
a lot of the time). Thus they became REALLY dependent on males
for the first time in evolutionary history. Males slowly 
started to call more of the shots.

And as we know, males have this thing about paternity, wanting
to ensure who's whose (in contrast to females, who have no particular
evolutionary interest in getting the same guy who fathered their
kids, to help raise them); so rigidified mating could have replaced
flexible promiscuity most easily at this time. (And the rest, as we say,
is--groan--history.)

>> >Did it happen when
>> >the male and female populations became more even?  

Sex ratios at birth are ALWAYS nearly even, at least for mammals.
This is a biological "fact". 
Thus when you have a situation (animal or human) in which polygyny
(a male with >1 female mate) or polyandry (a female with >1 male mate)
occurs to any significant degree, there are always surplus males or 
females left over. Among mammals polygyny is far more common, so
it's bachelor males who are commonly left over and--such as in 
many monkey species and I think also deer and wild sheep and such--
who often form "bachelor male" groups that forage together.

-----------
Susan Nordmark
Internet: kevin@chromo.UCSC.edu			
UUCP: ...ucbvax!ucscc!chromo.kevin		Santa Cruz, CA