Evolution, "adaptation", and what's currently adaptive

Bryant (mycol1@unm.edu)
19 Aug 1996 01:03:01 -0600

Joel said:

>I'll grant you, in
>a society which does not believe in birth control, people who derive great
>pleasure from their orgasms might well reproduce more often. Or they
>might not....

This speaks to the debate I mentioned earlier, about folks thinking that
evolutionists are claiming that people behave in ways which maximize
their fitness. Some, notably Darwinian Anthropologists, do. Most, like
sociobiologists and Evolutioanry Psychologists, do not.

I'd like to take your clause about birth control, which describes all
human populations in the Pleistocene, as an opportunity clarify my point
about this debate, even though I recognize that you didn't touch on this
issue. I've responded to your points elsewhere, just a few minutes ago.

Here's the deal, from my perspective: Jealous rage and sugar cravings
both potentially lead to fitness impacts. Rage puts a fella in prison,
and if he's not yet reproduced, that can earn him a net reproductive
fitness of zero. Yet it's apparently a species-typical trait. Why?

Sugar cravings, if they result in heart disease or obesity that negates
reproductive success, also hurts fitness in modern environments, yet the
culture hasn't been found in which people don't dig sugar. Why?

The evolutionary psychology type of evolutionist would say (and many
Darwinian Anthropologists would probably agree) that these instincts
evolved when mate guarding increased male fitness and sugar cravings
encouraged ancestral humans to seek out this limited nutritional resource
from their environs (also enhancing fitness).

In the short time since the agricultural "revolution" (and even shorter time
since industrialism), the relaxed (or reversed) selection pressures on these
traits have not had sufficient time to restructure our brains. (Some
would argue additionally that our brains may be structured in such a way
that we can't "un-evolve" our sugar cravings and jealous reactions; this
is known as "constraint." Gould likes this idea a lot, though hasn't
actually used it to explain jealousy or sugar cravings.)

Many critics of sociobiology suggest that if a given behavior doesn't
increase the number of babies one has, it cannot be explained in
evolutionary terms. For the above reasons, this is a mistaken criticism.