Re: can descendants of single couple multiply into large viable population ?
- From: William Morse <wdmorse@xxxxxxxxxxxx>
- Date: Sun, 21 May 2006 23:36:22 -0400 (EDT)
iler.ml@xxxxxxxxx wrote in news:e4o2ui$13og$1@xxxxxxxxxxxxxxxxxxx:
We had argument on IRC recently, whether, genetically
speaking, descendants of the single couple of humans can
grow into viable population ? (the arguments started from
somebody mentioning that [he read somewhere that] it
was genetically found that all native population of
one continent was descended from a single couple.)
They may be confused, and are extrapolating the "mitochondrial eve"
hypothesis to assume that there was a single ancestral couple.
Some people argued that it was impossible that inbreeding
and recessive pairing (correctme) makes the [whole]
population unviable.
Whether inbreeding would prevent the extreme population bottleneck of a
single couple from leading to a viable population would depend on how
inbred the population was to begin with. If the population was already
highly inbred, the additional inbreeding due to reduction to a single
couple might be survivable.
Others argued this is possible, because even if some part
of population suffers from genetics defects, sufficient part
of population has healthily mixed genes
I think when animals migrate to remote places, like
to remote islands, there must be cases when single couple
produce viable population. I think this must happen with humans,
too, through the long history of human migrations.
You are probably correct regarding colonization of islands by migration
of single couples for many species, but there are additional
complications for humans:
First, humans have so few offspring per generation that, even in the
absence of competition from other humans and diseases passed on by other
humans, the population is likely to become extinct simply due to chance.
Second, modern humans have a fairly strong innate tendency to avoid
incest, so the offspring of a single couple might simply refuse to mate.
Third, modern humans certainly prefer and may require a larger social
structure than just the nuclear family. It may be possible to raise a
child without a village, but it may require at least several additional
helping hands.
But I'm not biologist and I can't really argue for this. So:
can descendant of single couple multiply into large viable
population ?
On the basis of the above, for humans, I would argue that it is highly
unlikely. For faster breeding animals it is much more likely.
Yours,
Bill Morse
.
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