Re: Selection by Migration

From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Fri Nov 23 2001 - 07:06:20 MST


Jacques posted some thoughts on selection by migration
which J.R. poured at least some water on.

I've observed the effect that Jacques discusses in the
U.S. -- historically the less risk averse migrated West.
In modern times one tends to see young people migrate
to the less conservative coasts, esp. say New York,
San Francisco, or L.A.

What I think is at work is a "risk aversion" or "adventure
embracing" gene (or genes). Migrating always has risks
associated with attempting to survive in unknown environment.
At the same time it may provide the opportunity to gather more
resources (enrich oneself) and therefore support larger numbers
of offspring. From a prehistoric perspective, apes
had to learn to migrate to regions of the forest where
food sources became available at different times of the
year (this generated our mental ability to recall "maps"
most likely). As man became more of a meat eater he had to
migrate to follow the animals. However migration
(unless one is following paths which the tribe
discovered previously to be safe) *is* risky.

So in ape societies where the Alpha males dominate
the mating opportunities, there may be an advantage
for the non-alphas to migrate -- perhaps discovering
a "tribe" where there may be mating opportunities.
A better strategy is to select an immature female
and "elope" to a new location and start a new tribe
(where one is the alpha male).

Because migrating to new regions, eloping, etc. to
is risky it has to be balanced against the reproductive
advantages it might provide. So I think evolution would
develop two alleles for risk taking:
  R - take risks and r - don't take risks.
So a normal population distribution will be:
rr (25% - never migrate),
Rr (50% - sometimes migrate -- particularly when
          resources are in short supply),
RR (25% - migrate at the first opportunity or when any
          advantage seems likely).

Obviously if you have three alleles for 1 gene or 2 alleles
for 2 genes you get an even more interesting fractions and
patterns of risk tolerance. The advantages to the genes is
obvious -- it provides a stable base in a known environment where
the current gene set is known to "work" while at the same time
providing mechanisms for spreading the genes to prevent extinction
in the event of local catastrophes. The long term application
of this probably drives speciation as migrating populations
diverge and become better adapted to new environments.

In this light, extropians are perhaps turning into a new
species of humanity.

Robert



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