Archiver > GENEALOGY-DNA > 2010-02 > 1265914620

From: "Alister John Marsh" <>
Subject: Re: [DNA] Puzzled
Date: Fri, 12 Feb 2010 07:57:00 +1300
References: <>
In-Reply-To: <>


You said
May I suggest (perhaps to be ridiculed) that in the big picture it is to
ensure we have genetic diversity in the human species.

A degree of "genetic diversity" is good, but "genetic appropriateness" is
also important. When looking at very distinctive environments, the genetic
diversity and genetic appropriateness should be suited to that particular

I think in an Iceland study, they found that a person marrying a 2nd cousin
had more descendants than a person marrying a completely unrelated person,
or a closer relation.

I wondered if a 2nd cousin was similar enough culturally to easily enable a
stable family, but genetically diverse enough to avoid problems on

Marrying a second cousin perhaps increases the likelihood that a person is
marrying a person genetically adapted to the particular environment where
you live, and the offspring of that partner would be suited to that
environment. A fair skinned partner might be a better contributor for DNA
to offspring in a cold environment with periods of low sunlight, but a dark
skinned partner might be better in areas near the equator, with high
sunlight. (Horses for courses?)

In the modern World where people regularly travel to different environments
the situation may be a little more complicated. But my feeling is that
selecting breeding partners which have "genetic appropriateness" to the
environment where your children will live must be quite helpful.

If with global warming, and continental drift, Iceland becomes a tropical
island paradise, perhaps Iceland might have to consider importing some stud
lines from tropical areas to bring some tropical adapted genes into the

If the human race ever gets into colonizing distant planets, or galaxies,
rather than selecting genetic diversity for the founding populations, it
might be better if they select genetic appropriateness to the new


This thread: