Re: [asa] Two questions... (biological bottlenecking with Adam and Eve)

> But there would be no valid reason to say that 55.68723% is the dividing line- it would be entirely arbitrary... that's the whole point.

Yes, it's arbitrary, but one could hold that position-probably with
little success in persuading others.

> The Bible says Adam was made from a scoop of dirt and Eve was made from Adam's rib. To be consistent, they should both be literal or figurative- not one figurative (Adam) and one literal (Eve). If Adam was made from a lower life-form and not from literal dirt, then Eve would also not be made literally from a rib. Also- if Eve was made from Adam's rib- how would that screw-up the mitochondrial path? Eve can only get that from her mom, and she would have no mom in that case.<

Again, one could somewhat arbitrarily work out a system with certain
degrees of literalness, though probably not one that would satisfy
many people.

The mitochondrial situation would not be a problem. Each of us have
mitochondria, but normally only the female passes them on to
offspring. If the Y chromosomes could be miraculously replaced with X
chromosomes (at least in gonadal tissue), working out the proper
formation of gametes ought not to be a problem. Nevertheless,
anything like that is a rather strange mix of miraculous and ordinary,
and would be a hard sell.

> You say the most likely thing is that the fused chromosome happens in one individual then persists by breeding. This would rule-out Eve being Adam's counterpart, unless Adam was the father and Eve was his daughter, which does violence to the Scripture passage. Also by saying it is most likely- what is another option, if there is? The other option is that the fused chromosome arose in more than one individual (independently) and that at least two of these found each other and mated?<

The most likely scenario would be that they would be siblings or
cousins. I. e., the individual with the initial mutation has
offspring (probably fewer than normal). Some will have one fused
chromosome and one ancestral separate pair. They will have similar
reproductive difficulties to the parent. However, if two descendants,
each with one fused and one unfused, get together, some of the
offspring would be expected to have both fused. The ones with
matching fused chromosomes no longer have difficulty in breeding with
each other, but do have a barrier to breeding with those with unfused
chromosomes. This will favor the rapid development of premating
barriers to attempted breeding between the groups. Inbreeding,
certainly (and thereby even lower genetic diversity than an equal
number of randomly selected individuals), but that's also an issue in
the "where did Cain's wife come from" type of question.

It's possible that some genetic feature, found in more than one
individual, made that particular fusion more likely, but I know of no
evidence supporting that. Without such a predisposition, the odds of
two individuals indepedently having that same mutation is rather low,
though not absolutely impossible.

-- 
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
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