Re: Social evolution of hominids

ailak@walrus.megabaud.fi
13 Jan 1997 15:03:11 +0200

susansf@netcom.com wrote:

> Evolutionarily speaking, there's not a great incentive for males of
> the species to mate with only one female for life. That's why
> monogamy in a very strict sense (one mate for life, as in the
> gibbons) rarely happens in humans. The reasoning behind this is
> fairly obvious for the male, try to spread those genes around as far
> and for as long as he can. Monogamy does make more sense for the
> female, since her reproductive resources, unlike that of the male,
> is fixed. Promiscuity would not produce more offspring, just confusion.

Let's make a rapid analyse of this! These men mate with several
women, their genes spread in the population, and in due time, most
men are promiscuous and mate with several women. For the women,
monogamy is an evolutionary more sensible solution. This means that
in due time, most women will be monogamous and mate with only one man.
Evolutionary speaking, it somehow does not work... :)

What if both men and women were promiscuous, to a certain extent, as a
remnant from a long, long promiscuous period in the prehistory of our
species. We are only learning, how to be monogamous?

>I don't know that this behavior pattern in human females could be termed
>"fixed" genetically, aside from the fact that XX sex chromosome tends to
>result in less promiscuous sexual behavior. Professor Vince Sarich used
>the following example in his evolution of human behavior class, namely
>"How many male prostitutes are out there, compared to female prostitutes?"

This behavior pattern in human females *can not* be termed as fixed.
If it was, no woman, ever, could have sex but with one man in her
life, as far as he lived. This is how it is with the gibbons? Now,
take a society which denies all exceptions from strict monogamy. It
will favour people, who have an inborn tendency to stick to the first
man or woman with whom they have sex. Marriages between such people
yield more succesful children than marriages, where one or both
parents seek outside sex and get in trouble for it. In this way the
social environment selects for traits which fix monogamy at the genetic
level. They are not sexual, but mental traits, and they cover males
as well as females.

Prostitution in our society has historical grounds, and average women
never could afford a prostitute, even if they would have wanted.
Where women had power, like queens and the top class, they used any
man who pleased them in their vicinity. It has also been stated, that
XX results in less sexual desire... Depriving the cultural context, I
don't think his argument holds.

> Sex once a year... very doubtful any primate species would survive
> such a reproductive cycle... non-conception, miscarriages, non-viable
> offspring... when this occurs, the next reproductive opportunity is
> quite a few long months away.

A host of animals can reproduce just at certain times a year.
Primates live in rainforests, mainly, and have a continuous food
supply. It is possible, that this was needed for further evolution.
Yet, two surviving offspring per female, for her lifetime,
in average, is enough for the species to survive, too.

> Now why on earth (or anywhere else) would a male
> stay around for this type of reproductive behavior?

You may ask the rooks. They are monogamous for the whole life, and
they have sex once a year, when they nest. The wolves have a
dominant male and a dominant female. Each of them fights
independently his and her way to the top. They accept each other
as far as they are in command and make a pair, the only
reproducing pair, and have sex once a year. Many savanna animals
reproduce once a year, which means sex once a year even for a male
with a harem. Big animals often have pregnancies close to a year.
There are different survival strategies, and sexual strategies
belong to them. They depend. Do you really think, that it is the
physical sex, not mental traits, which determines pair binding?
Continuous sex is an exception in the animal kingdom, not the
rule!

>The whole concept behind Lovejoy's theory is that since sex and
>the *possibility* of conception, therefore offspring, is continuous,
>year round, throughout the entire month, pair bonds become a better
>reproductive strategy out in the "savanna"...
snip

Hmm. Sounds complicated. How often do chimps ovulate? Somehow there
are ovulations and prolonged receptivity mixed. It is the length of
pregnancy and lactating, not the interval of ovulations, which
determines the birth rate. A female which has no climate-dependent
reproducing cycle is usually either pregnant or lactating. Not many
ovulations in her life.

Susan 

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                                             susansf@netcom.com

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Aila Korhonen in Finland                 ailak@walrus.megabaud.fi