Peez

LOL! Very good. It can get a little complex, but the bottom line is that we have all inherited out mitochondrial DNA from "mitochondrial eve," but we have inherited other DNA from her contemporaries. Thus there could have been any number of humans alive and breeding successfully at the same time as mitochondrial eve.If one starts with "perfect" genes, then inbreeding is not a problem. However, one does have the problem of explaining how we got all the genes we have today (it would involve evolution much faster than that accepted by biologists to go from Noah and his family to today's diversity).

Peez

CaptainOfOuterSpace

For empirical results of human inbreeding, just visit southern Ohio!

Peez

Inbreeding problems arise because we all carry recessive genes that can cause health problems. As long as we have children with someone very distantly related, it is very unlikely that both parents carry exactly the same recessive gene, so it is very unlikely that any child born will get two of these recessive genes and therefore be ill (they have to get one from each parent). On the other hand, if you inherited this recessive gene and so did your sibling, there is a much better chance that one of your children will be born with two of them.

Now, if Adam and Eve had no such nasty recessive genes, then there is no inbreeding problem. However, if even one of them does, an increased lifespan or otherwise increased reproductive output will not help eliminate the nasties. The bottom line is that no matter how many children they have, all of these children are related to each other exactly the same degree.

Peez

RufusAtticus

A&E might have had perfect genes for the Garden of Eden, but as soon as they got kicked out, they're non-longer in the Garden so all bets are off. Low genetic diversity + environmental shift + inbreeding = extinction.

Peez

Oh crap, when will I stop thinking like a scientist?

But, if you really want o go that way...
inbreeding leads to the expression of recessive genes, which includes those which might prove useful in a novel environment! This could give natural selection something to get some traction on.


Peez

Rational BAC

I'm still curious about the idea that intense inbreeding (brother sister) either due to the Genesis account or to one of many possible evolutionary accounts--------would definitely cause the demise of a species.

I would expect such inbreeding to cause very high child mortality rates due to recessive genes. Of course those children would not reach the age of puberty and could not procreate those recessive genes. Those "defectives" who did manage to reach the age of sexual maturity, would probably find it difficult to survive, and even more difficult to find a mate.

So wouldn't the recessive genes after many many generations end up being a very minor problem?------just like they are today.

Even though with a highly inbred (brother/sister) beginning, wouldn't natural selection eventually "breed out" most of the species killing recessive genes?

Now I am talking about VERY high mortality rates due to recessive genes at the beginning. Maybe 80% 90%. But just like the problem we have today with the overuse of antibiotics, wouldn't the strongest survive, even on a human level?----given enough numbers and enough time.

I see no obvious reason why the inbreeding in Genesis could not have worked out eventually (except for the ridiculously short time frame). I see no reason why evolutionary inbreeding could not have worked out, even more definitely, with much longer time and much larger numbers also.

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And there is still the second puzzle. We can theorize all we want to, but do you mean to tell me that absolutely no one has tested this empirically? Using dogs, cats, bunny rabbits, even fruit flies (as someone mentioned).

Very simple to do. Would take maybe 30 years to see if inbreeding would definitely cause extinction. (Much shorter time if used fruit flies).

I suspect, all theories aside, that "life will out" (or maybe it was "life will find a way"---from that dinosaur movie) no matter if that life started with brother/sister incest. And therefore Genesis is technically possible and an actual evolutionary "Adam and Eve" is even more possible.

Someone stated that the evolutionary Adam and Eve (or at least Eve) had to be at least 250 people for it to really work. I doubt that.

In any case, the problem can be easily tested to find out. Or am I missing something obvious here?

conkermaniac

I think that Oolon meant that there needed to be hundreds of genetically different people. If these hundreds of offspring were all born from Adam and Eve, their internal genetic structure would be similar, and thus inbreeding between the children would magnify the "bad" genes carrying certain medical conditions. I'm not an expert on DNA, so I'm probably not using the right terms, but I think (or at least I hope) I've gotten the basics nailed down.

Rational BAC

Me too Conker. I am just a layman in this. No expertise here.

I hope that those who are more knowledgeable in these things don't just blow off these questions as not worth replying to.

I think they are good simple questions. Hope for good simple answers.

sakrilege

Actually, northern Ohio has a problem... Geauga County Amish

Roller

Would crossing over occur between chromosomes of the same genetic makeup? From the way I see it, crossing over depends on distance between genes on the chromosome. If that distance is not big enough, genes could be linked and therefore unable to assort independently.

If this were true, than no genetic variation would be possible. Until mutations kick in, of course, but those would have to be fast as hell (no pun intended).