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Author | Topic: Human Chromosome 2 and the Evolution of Humans | |||||||||||||||||||||||||||||||||||||||||||
PaulK Member Posts: 17828 Joined: Member Rating: 2.5
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Of course, the fact that it is a fusion is strong evidence for the evolution of humans (and yet one more example of how evolutionary explanations could be falsified).
If the fusion occurred in a single individual then they must have still been fertile with the rest of the population. Otherwise he or she would have left no descendants. This in itself is reason for doubting that the fusion caused the split - or any of the later splits in our lineage. As to the timing of the event, I will simply note firstly that there are non-homo species between us and our common ancestor with the chimps (likely among the australopithecines) and secondly that we have relatively little data to go on. So far as I know we don't even have a chromosome count for Homo erectus. Which leaves us no basis for saying that all Homo species had 46 chromosomes. If we simply use chromosome count as a basis the fusion event could have occurred before the split between our ancestors and those of the chimpanzees or after our ancestors split from the Homo erectus population. There's no way to tell without additional data.
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PaulK Member Posts: 17828 Joined: Member Rating: 2.5
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quote: The evolution of humans from (other) apes would be seriously called into question if we had no plausible explanation of the difference in chromosomal arrangement. The fact that not only do we have an explanation, but that the explanation is strongly supported by the evidence shows evolution passing a significant test with flying colours.
quote: Do we classify the '44 chromosome man' as a different species? And on what criterion would we do so? Not on the morphological criterion or the criterion of reproductive isolation, which are the two most likely to be applied.
quote: The split would have to occur at the point where the populations diverge and interbreeding ends (there are nuances, but that's close enough). Did the chromosomal arrangement cause that? I don't think that there is a strong case that it did - and even if it did, it wouldn't happen immediately.
quote:which was my point :-) quote: Neanderthal and Denisovan are the only two, I think.
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PaulK Member Posts: 17828 Joined: Member Rating: 2.5 |
quote: You need to be careful there. That is the position some ID supporters retreat to, since the actual IC argument has failed but even there they demand a huge amount of detail, which I do not. The key issue is the level of knowledge we have. Obviously we do not have the knowledge to reconstruct the complete history of a complex adaption including all the relevant mutations, in order and the selective pressures that caused them to become fixed in the population. By my understanding we do have a fairly good idea of the sorts of mutations that are possible, and if we could not explain the chromosomal difference in those terms we would have a problem. If we did NOT have that knowledge, it would be a different matter.
quote: Of course you are assuming infertility, but it would seem a huge leap to conclude a new species without morphological differences. While cryptic species do exist I think that we would want a little more. And don't forget that the article on the 44 chromosome man says he would have fewer infertility problems than his parents, even if his partner had 46 chromosomes.
quote: Well it isn't a plausible explanation for the whole evolution of humans and chimps, at most it is a component of how the populations that evolved into humans and chimps diverged. The very fact that the new chromosomal arrangement was able to spread into the population and persist argues that the infertility problems were not too severe, at least at first. However, there's a problem here. The chromosomal difference can only significantly contribute to one population split, one speciation event. But there must have been several between us and our common ancestor with the chimpanzees. How do you narrow it down to the split between our ancestors and those of chimpanzees rather than one of the later speciation events ?
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PaulK Member Posts: 17828 Joined: Member Rating: 2.5 |
I think that with an effective population size of only 5 humanity would probably go extinct. And that's without assuming a population of only 2 a couple of thousand years earlier which would make things even worse.
Aside from the genetic issues, though, I don't think that there is necessarily a barrier to the actual population size increasing hugely since then (although I think we'd still be behind current population). That said, good as the genetic evidence is, if you put the flood 4350 years ago I don't think that the archaeological evidence shows any culture being wiped out and replaced at that time. Not even the Sumerians. If you want to avoid archaeology, you'd have to go further back in time.
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PaulK Member Posts: 17828 Joined: Member Rating: 2.5
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quote: Disappeared as in vanished ? Certainly not. Conquered and absorbed by other peoples, yes. Slowly lost to change and time, yes. But certainly not - just gone, in a single event.
quote: I believe that there's evidence of some serious flooding during the Sumerian period. In fact there seem to be multiple flood events - at different sites (i.e. the flooding is local, even within Sumeria, there's no single flood affecting the entire region).
quote: Looking at Wikipedia: Sumeria was conquered by the Akkadians around the time of your Flood (dating is uncertain), with a revival following the downfall of the Akkadian Empire. Agricultural fertility was declining due to increasing salt in the soil (itself a consequence of poor irrigation and the dry climate), weakening the region. Sumeria was absorbed into the Babylonian Empire circa 1700BC and never reestablished itself after that. Edited by PaulK, : No reason given.
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PaulK Member Posts: 17828 Joined: Member Rating: 2.5 |
As I said, for effective population size we don't count Noah's sons, so the number should be 5... (Even without the complication of a recent genetic bottleneck not so long before that !)
I don't know where ForeverYoung got 7 from. Probably he meant 8. Edited by PaulK, : No reason given.
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