On Thu, 6 May 1999, Bernard Lischer wrote:

> With respect to grains and (seemingly to a lesser extent for you) dairy, one
> has to remember that the very oldest use is around 10,000 years ago.  That's
> only about 300 generations.

I would count 20 years, possibly less, as a generation during
most of that time, which would push it to 500 generations.   This
does raise interesting questions, however, about evolution.

You have indicated, for example, that the possibility of people
having eaten stomach-fermented cheese for a long time does not in
itself mean that this food was eaten often enough to amount to a
significant selection pressure toward adaptation to dairy.  This
may be so, but it causes me to wonder when selection pressure is
indeed significant.

For example, if a new food causes people to be somewhat sicker,
without killing or incapacitating them outright, does it provide
selection pressure toward adaptation?  Yes, it does, since sick
people are less attractive as mates.  On the other hand, if that
new food is plentiful enough to allow for population expansion,
the population that consumes it, though sicker than the
population that does not, will dominate in the gene pool.

Furthermore, if you accept the neodarwinian assumption that
adaptation is driven by random mutations, then there are no
guarantees that adaptation will happen, no matter how long people
are exposed to a given food.  This is especially an issue if
adaptation requires multiple simultaneous mutations (i.e., if 3
mutations are required to have no problems with a certain food,
but individually those mutations confer no advantage).  This
implies that the mere fact that people have been eating a certain
food for a very long time does not imply that it doesn't make
them sick; it only means that it hasn't killed them off.

Todd Moody
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