Text 1212, 73 rader
Skriven 2004-12-29 06:21:00 av Malcolm (1:278/230)
Ärende: Re: How come every new ra
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"pslant" <pslant@yahoo.com> wrote
>
> If we all can be traced back to some common female ancestor (looking
> at the maternal line), wouldnt that require extreme inbreeding ?
> Is it correct to state
> 1) she was the first female human
>
No. The first female human would be the earliest woman who could have
fertile offspring if impregnated by a modern man. Her mother would not be
able to conceive such ofspring.
However a better definition for popular purposes would be "the first woman
men in ordinary speech would call a human", and it very difficult to know
where most people would draw that line.
>
> 2) she had children with a "non-human" , lets call that "race"
> sub-humans.
>
So this doesn't really follow. The men might have been sexually compatible
with modern women for many generations before the women became sexually
compatible with modern men.
>
> 3) for some reasom they (or some) shared her human characteristics
> 4) her female offspring were sired (is that the correct term?) by
> other sub-humans.
> at least some of those children ALSO had human characteristics
>
"Humanity" could be a Mendelian trait, in the sense that one gene arose
which gave a "soul" (consciousness, language, free will, the ability to talk
in terms of right and wrong, knowledge that the sexual act leads to
procreation, take your pick). So if it were dominant half her children would
be "human". If it were recessive, you would have a few generations of
non-humans again, until someone else acquired two copies of the allele.
>
> Wouldn't it be necessary to start breed between the human group fairly
> soon in order to not dilute the "human" strain?
>
> How can that small polulation produce over 20 billion people?
>
> What's the error in my reasoning ?
>
You are sort of correct. In fact humans did go through a narrow genetic
bottleneck when the population was at most a few thousand. It is not
unreasonable to suppose that this was associated with an event that gave us
our special characteristics, but we don't know this for certain.
However, "Mitochondrial Eve" is the most recent common ancestor of all
women. By definition she must have had at least two surviving daughters.
However there is no reason to suppose that both of these married the same
man, nor that her grandchildren married closely-related people. However all
humans who traced ancestry through another female line must have eventually
died out. So the answer is that gentic diversity may have been maintained
through the males.
>
> If the answer is that "race" is a more continuous that step-wise
> fenomenon, how come "sub-humans" arent here now, or are they?
>
Human races are continuous, but we don't know whether this is because of
interbreeding at the margins, or because the races are in the process of
diversifying from a geographically wide ranging but homogenous ancestral
stock.
Most biologists discount stories of elves or Yetis, but the recently
discovered Indonesian hominids survived until almost into the historical
period. Modern humans would have been close competitors with any other
hominids, and probably we drove our relatives to extinction.
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