Re: primates and sex

Gerold Firl (
22 May 1995 13:22:42 -0700

In article <3pb6v2$> ([Stephanie Fishkin) writes:
> (Gerold Firl) writes:

>>Using this perspective, it is clear that STDs would tend to exist among
>>promiscuous species such as humans and bonobos; among strictly monogamous
>>species such as the gibbons, or solitary species such as orangs, STDs have
>>no transmission mechanism.

>I was thinking of an argument along the lines
>that more monogamous species would be more susceptible to
>STDs than less monogamous primate species (the idea being
>that those more promiscuous species of primates may have
>evolved to be less physically susceptible of STDs -- because
>of wider exposure to them -- than less monogamous ones).
>Sorry if this doesn't make much sense, it's more of a
>not-well-thought-out idea at this stage; I'm just trying to
>track down references.

I can't provide you with references for this issue specifically, though I
would recommend william macneil _plagues and peoples_ for an overview of
the ecology of population and disease together with their historical

Again, I suggest that you need to reverse your idea of causality regarding
the prevalence of STD's in different kinds of populations, and also look at
the co-evolution of diseases and their hosts.

When a disease first takes root within a new host population, it is
extremely virulent, which leads to rapid evolution. When the host dies
quickly, there is a good chance that the disease organisms die with it.
This leads to both an increase in the resistance of the host, and a
decrease in the virulence of the disease. Eventually, an equilibrium is
formed, where the disease either becomes chronic or disappears altogether.

Keep in mind that diseases are pretty specific to a limited set of target
hosts. Some diseases can live in one of several species, but many are
specialised for only one. For this reason, STD's will not exist in
monogamous species such as the gibbon, though it is possible that an
organism which evolved to use another species as host may be versatile
enough to cross-over.

As far as promiscuous species evolving methods of minimising the risk of
infection from STD's - it's possible. The obvious place to look would be
the mucous membranes of the genitals, since that is the point of entry for
STD's. Bonobos would be the most promiscuous of the primates, so they would
be a natural place to start looking.

Disclaimer claims dat de claims claimed in dis are de claims of meself,
me, and me alone, so sue us god. I won't tell Bill & Dave if you won't.
=-=-=-=-=-=-=-=-=-=-=-=-=-=---- Gerold Firl @ ..hplabs!hp-sdd!geroldf