I have to disagree; yes, there always was "wealth" throughout all of
human history, just as there is in aboriginal societies today. It's
likely to be measured in plots of land, cattle, wives, social status,
or whatever else the particular society valued. "Money" is just a
convenient form of measurement for wealth that we have created in
recent times to simplify the act of trade, but the concept itself is
a much more fundamental one.
And yes, anything that affects behavior can be "encoded in DNA". The
fact that the first step in the chain of gene->phenotype happens to be
protein synthesis is no reason to discount phenotypic effects that we
cannot necessarily trace back that far. /All/ phenotypes involve
convoluted interwoven reactions among coded proteins, the embryonic
environment, and the living environment. To assume otherwise would
be to argue conscious design.
What we actually mean when we say "a gene for X" is that some gene at
some particular locus in the genome, all else being equal, will be more
likely than its alleles to result in trait X being expressed in the
organism. It implies no specific cause; it may increase the emotional
response to some stimulus, thereby encouraging some behavior; it may
make some morphological change that reduces the energy expended on some
behavior; it might make some purely cosmetic change that affects the
way other organisms behave when seeing you.
The question, then, is how might a gene that had the effect of reducing
a wealthy person's desire to breed might have become more numerous than
its alleles in future generations. At first, this seems impossible--
typically, genes survive when people breed more, not less, and wealthy
people are better able to care for more children. But evolution has
done stranger things. Even a trait as drastic as sterility in worker
ants can be shown to be an adaptation of the peculiar haplodiploid
genome of eusocial insects.
Perhaps the trait came about from periods of boom and bust in the
climate. Families with fewer children wound up fatter in boom times,
and tended to survive the next drought better than large families of
skinny kids. If such droughts occured on the average once or twice
per generation, such behavior might well have produced more grandkids
for parents who fattened up one or two kids that those who wastefully
bred more just to die out. This is pure speculation, of course, but
some such mechanism is quite plausible. All that is required is that
/some/ gene had /some/ effect that caused a difference in behavior,
and that behavior caused a difference in reproduction.
I would tend to suspect other social causes for the effect, but I
wouldn't rule out genetic basis or predisposition.
-- Lee Daniel Crocker <lee@piclab.com> <http://www.piclab.com/lcrocker.html>