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Thursday, June 12, 2008
Mammoth mtDNA wholly sequenced from hair
Source: Science Daily: Woolly Mammoth Gene Study Changes Extinction Theory.
The study, published in PNAS, has several interesting findings:
Mammoths were not one but two species, that had diverged one million years ago, one of which became extinct c. 45,000 BP, some time before modern humans arrived to their habitats.
Both mammoth species had low genetic diversity, what is curious for an animal that ranged from Europe to North America.
The mtDNA of mammoths was a lot more complex than their elephant relatives, either African or Asian.
They managed to generate and compare 18 complete mitochondrial DNA sequences, a unique feat in the field of aDNA studies. They could make it because they worked with hair, not with bone, what evidences that hair preserves aDNA much better than any bone tissue.
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6 comments:
Thanks Maju. I couldn't find where the two populations lived anywhere in the article. Especially where the one that died out 45,000 years ago lived. Perhaps it is evidence of earlier human arrival than currently believed?
Regarding the genetic diversity. I think it may indicate that the population, although widespread, was of limited size. In other words with very little food in their environment they required very large territories.
I couldn't find where the two populations lived anywhere in the article.
It doesn't say. Maybe in the paper but by the moment it's behind a paywall. I think PNAS frees all articles after 6 months anyhow, not sure.
Perhaps it is evidence of earlier human arrival than currently believed?
Well, Neanderthals were mammoth hunters too. I really can't say.
Regarding the genetic diversity. I think it may indicate that the population, although widespread, was of limited size. In other words with very little food in their environment they required very large territories.
I was thinking the same: large distance nomads maybe? Also it may be that they actually lived in smaller specific territories and the two species is all the sample has been able to discern. Maybe they were several species in different restricted areas?
I really can't but speculate with the info we have.
I agree Neanderthals were mammoth hunters but I think we agreed that modern humans introduced a more efficient hunting technique. The argument is over whether the hunting technique and genes crossed the boundary between the species.
You could be correct about there being more species than they identified. I read a book about mammoths years ago and it said there were five if I remember correctly. But this study was probably just concerned with woolley mammoths, of which the book claimed one species.
Anyway we know that all species that occupy a wide geographic region break up into species and subspecies if there is no gene flow.
Notice that elephants are organized in matriarchal and matrilineal packs. I wonder if that has to do with mammoths having low mtDNA diversity. It would not mean low gene flow necesarily, just fixation of mtDNA lineages.
I agree Neanderthals were mammoth hunters but I think we agreed that modern humans introduced a more efficient hunting technique. The argument is over whether the hunting technique and genes crossed the boundary between the species.
I understand that modern humans made a more efficient use of the territory. Certainly they had much larger hunt territories, in the line of what actual hunter-gatherers do but not what Neanders apparently did. Campbell has argued that this is because sapiens had sex-based division of labor while Neanders didn't, so our male ancestors could wander for longer in their hunt expeditions, without having to worry about the children.
But they probably also used resources that Neanders ignored, like fish or seafood and even probably smaller prey. Sapiens were more versatile apparently, while Neanders may have been more limited due to their culture.
Certainly culture may be altered and techniques learned, as our grat ape cousins show us continuously. Neanderthals certainly innovated or at least tried to imitate our techniques but they seem to have been just not as sharp an ingenuous as us in the end. It's difficult to evaluate the difference but there must have been some differences in spite of similar cranial capacity.
Also, going back to mammoths, notice that the date of 45,000 BP is just slightly older than Aurignacian and that other Sapiens groups were there from Bulgaria to the Altai to maybe cause the mammoth extinction.
But on the other hand, maybe the decline of Neandertals was generated by their own excessive dependence on dwindling mammoths.
We can't but speculate, I guess.
"the date of 45,000 BP is just slightly older than Aurignacian and that other Sapiens groups were there from Bulgaria to the Altai to maybe cause the mammoth extinction". The date's significance hadn't escaped me either. That's why I'm keen (I guess we both are) to find where that extinct population lived.
Your comments regarding matriarchal groups could well be relevant but as you say "We can't but speculate, I guess".
That's why I'm keen (I guess we both are) to find where that extinct population lived.
Either purchase the article or wait till December or January, when it'll be freely available without charge. :)
I'm certainly keen on knowing, so if you find something more let me know.
Your comments regarding matriarchal groups could well be relevant...
But they say this low diversity is in relation with actual African and Asian elephants. Of course, 18 samples is not the same as hundreds, maybe thousands, among extant proboscideans.
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