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Author Topic:   Genetic 'Bottlenecks' and the Flood
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Message 1 of 59 (16178)
08-28-2002 2:15 PM

I am wondering about the genetic bottlenecks which some of the paeleo-geneticists(?) have proposed. I understand that mitochondrial Eve need not necessarily have been the only woman alive at the time, but do not some of the theories suggest a very small breeding group of humans at some time in the past?

If this is the case, then there is an opportunity for the creationists to prove a point. The dates of such a bottleneck ought to match those for Noah and his family. Furthermore, there should be a similar bottleneck for all other animals, except fishes, matching the human dates.

I don't know if domestication and human breeding would upset such calculations - perhaps we would need to select cells from uncontrolled groups like wild birds. Would this be a sensible, credible and practical experiment?

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Message 3 of 59 (16182)
08-28-2002 3:12 PM
Reply to: Message 2 by John
08-28-2002 2:51 PM

[QUOTE]Originally posted by John:
Definitely a credible experiment. Wonder why the creationists haven't already carried it out? It would prove their point once and for all, after all.

I was hoping to get some idea of the difficulties and costs involved. For instance, I believe there was a need to take samples from a large number of humans spread over a wide geographic area. I was thinking that samples could be taken from migrating birds to minimise the amount of travel involved. This might give access to a large breeding population easily, but I am not sure of the detailed requirements.

If some estimates of the actual costs could be made, based on a proposed methodology, we could formally invite one of the Creation Institutes to undertake the experiment, or get a University interested. There would need to be a lot of consideration of the issues first, of course.

One line that might be taken is that the genetic mechanisms which were used for this dating were not valid in some way. So agreement would need to be achieved that what was being proposed would be a sensible test.

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Message 7 of 59 (16222)
08-29-2002 6:15 AM
Reply to: Message 5 by Mammuthus
08-29-2002 4:32 AM

Originally posted by Mammuthus:
Hi John,
I don't believe that would prove much if you found 6 species with evidence of a bottleneck 6K years ago. For such a test to have any relevance EVERY single species on Earth would have to have a genetic bottlneck and a coalescence time of 6000 years before present.

That's our point - the creationist theory predicts that all species should show this evidence.

In practice, of course, it would not be necessary for them to test all species. By the time they had got 6, 10 or 100 with such a bottleneck they would have very powerful evidence, and mainstream science would pick up on it. We are, I presume, quite open to being proved wrong in our assumption that there was no world-wide flood which brought all species down to 1 (or 7) breeding pairs?

Creationists do have a reasonable chance with this one. All populations vary in breeding size, and there must be some species which show a population dip at around the right time. Of course, it will not be enough to show that a single species has a dip - they must show that no species exhibits no dip.

Actually, out of curiosity, can anyone find a single example of a species that has been identified where the genetic bottleneck dates back to 6000 years ago? [/b][/quote]

Here is where we make a call to the creationists on the board. What I suspect will happen is that the techniques which are used to determine these bottlenecks will be questioned. So another part of this thread involves asking creationists if they accept the validity of these tests and their interpretation. Since the tests depend loosely on what we might call micro-evolution, which I undestand even the YE group accept, we should be able to pin down a position where they are forced to disagree with directly testable evidence.

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Message 9 of 59 (16242)
08-29-2002 11:53 AM
Reply to: Message 8 by Quetzal
08-29-2002 7:06 AM

Originally posted by Quetzal:
There IS evidence from at least one species of a genetic bottleneck around (very roughly) the right approximate timeframe. The cheetah (Acinonyx jubatus) is every conservation biologists' favorite example. .... The bottleneck is variously dated from a low of 4000 ya to 10-12,000 ya

Thanx - just what we were looking for. I wonder why creationists are not citing the cheetah as an example of the Ark's cargo - it looks like it could have been the only one! Of course, with hindsight, we should expect the only survivor on the ark to be a predator, and a single one rather than a pack animal.

By the way, the link you provided to the Menotti-Raymond, M. and O’Brien, S.J. paper does not work for me. I have tried unsuccessfully to find another - is there one you know?

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Inactive Member

Message 13 of 59 (16249)
08-29-2002 2:09 PM
Reply to: Message 12 by derwood
08-29-2002 12:42 PM

Originally posted by SLPx:
It has been proposed that modern humans descended from a single woman, the "mitochondrial Eve" who lived in Africa 100,000 to 200,000 years ago... The mitochondrial Eve hypothesis emanates from a confusion between gene genealogies and individual genealogies.

Thanx for the ref. As I said earlier, I understood that MtEve was not necessarily a bottleneck, but I had thought that some other research suggested that there was one somewhere. It is interesting to know that there is no bottleneck detected in Man, and equally interesting to know that there is in some other species. I am wondering what the creationist position may be on the acceptability of this research, given they seem to accept 'microevolution'.

[This message has been edited by Me, 08-29-2002]

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Message 16 of 59 (16400)
09-02-2002 7:05 AM
Reply to: Message 15 by Quetzal
08-30-2002 5:15 AM

[B][QUOTE]Originally posted by Mammuthus:

In fact, I'm rather surprised the creationists HAVEN'T used the cheetah as "proof" of the flood. Maybe the whole bottleneck thing is too esoteric. Or maybe since it's 10k rather than 4k it isn't close enough to make sense.


I think we have established a new view on living conditions in the Ark with as much assurance as the creationists usually work with. We have now 'proved' that the Ark was launched, but that the predators got out of control and ate all the specimens, leaving a single cheetah pair surviving. They probably climbed the mast while the carnage was taking place below, and ate all the monkeys. Perhaps we could start our own religion on the strength of this astounding insight!

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