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From: "John McEwan" <>
Subject: RE: [DNA] New Populations
Date: Mon, 24 Apr 2006 21:53:01 +1200
In-Reply-To: <E1FXgqx-000Duv-Q4@mk-webmail-1.b2b.uk.tiscali.com>


Dear Gareth

You asked a fair question and I would have loved to see a good reply, so
because there was none here goes.

Hunter-gatherer groups were typically quite small I understand usually
below 50-100 or so people and often consisting of highly related males
and less related females (typically exogamy was also practiced to some
extent). This has to do with game/food density and inability of this
lifestyle to support major population centres unless there was a
reliable foodsource (like salmon in Northwest US). I stated yesterday
that a hunter gather group may be a 0.15 people per km2 so 100 people
would need an area of 670 km2 to support them. This is a region with a
radius of 10 miles, but typically it interfaced along coasts or rivers
and avoided barren regions so it may have been 2-5 times that distance.
Others may comment.

So now we get down to what is the minimum founding family. We can take
the settlement of the Pacific islands, Iceland, America ..... and look
for examples. From a genetics point of view 50-100 people is about the
minimum, but it could get down to perhaps 20-50 people (a boatload for
pacific settlement) to avoid severe inbreeding and potential genetic
meltdown. It is interesting that 50-100 is the effective minimum from an
inbreeding perspective and is also the size of a typical hunter gatherer
groups. However, 100 people is 50 males, but if it was a typical group
there may have been only 5-10 possibly even lower "novel" Y chromosomes
and going through a bottle neck and recovering afterwards there is a
good chance that many of the Y lines could disappear just based on
random genetic drift. Typically Y chromosome haplotypes will be fixed in
2N generations where N is the population size of males, but it could be
less that this if there is bias in the contribution to the next
generation.

I know that there is quite a bit of literature on this topic, so would
be keen to hear others views.

Cheers

John McEwan

-----Original Message-----
From: [mailto:]
Sent: Monday, 24 April 2006 3:50 a.m.
To:
Subject: Re: [DNA] New Populations

Ken

I don't think you could call a founding family a "population" unless
they
were totally isolated and self-sufficient.
Does anyone know what might have been the smallest viable size of a
self-contained group of hunter-gatherer humans?

Gareth





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