From: Hal Finney (hal@finney.org)
Date: Tue Apr 15 2003 - 18:50:21 MDT
> Eur J Nutr 2000 Apr;39(2):67-70 (ISSN: 1436-6207)
> Eaton SB; Eaton SB
> contemporary humans were selected. Our genome can have changed little since
> the beginnings of agriculture, so, genetically, humans remain Stone
Damien Sullivan writes:
> See, it's that "can have changed little" which I frankly question. It's been
> 500 generations. The Grants in the Galapagos have seen genetic shifts in 20
> generations. If a diet of grains had been that bad for us, I think that'd be
> a corresponding strong selection pressure to get better at eating grains.
> Lactose tolerance among Caucasians is one minor example of adapting to the
> local diet. And is it speculated that American Indians and aborigines have
> less tolerance for alcohol since they're new to it. (They have a weakness to
> it, but whether that's cultural or metabolic I don't know.)
I have to agree with Damien. Even though the genome changes slowly in
terms of new mutations and new genes, what we need to look at is the
gene pool. What is the distribution of the various genes, which ones
are prevalant and which ones are rare. The gene pool in a population
subjected to new selective pressures can change very quickly; as Damien
says, in just a few dozen generations.
Especially given that a prehistoric diet was highly variable and
uncertain, individuals within a group would probably have evolved a
variety of digestive and dietary genetic strategies which would have
coexisted in equilibrium. One person would do better in times of famine,
another would be better suited to exploit times of plenty. Some could
digest grains better, others meat.
Then once you throw in 5000 years of agriculture, the gene pool is going
to change enormously, as the selection pressures for eating and digestion
are so different. It's pretty certain that the gene pool for us today is
very different from the one that existed in prehistoric times. The set
of genes that exists today may not be different, but the proportions and
distribution are going to be totally changed. It's highly unlikely that
a random person today would have very similar digestive capabilities to
those of a cave man.
Hal
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