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Thanks decimon!...started to become extinct in Europe 24,000 years ago... international team of scientists has analysed mitochondrial DNA sequences from 17 new fossil samples... show that the decline of the cave bear started 50,000 years ago, and was caused more by human expansion than by climate change.That must be some damned detailed mtDNA. What a ridiculous mess. |
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And here I thought that stuff like that was encoded into the RNA, so we could encapsulate it, swallow a pill, and not have to show up for lecture classes...labs still required.
The reporter indicates that as there were fewer bears there were fewer different sorts of mtDNA ~ yet, the thesis here is that human presence was depriving the Cavebears of food ~ that is, range.
Think about that a moment. We have human beings, and as they spread out into more and more isolated groups way-back-when there's less breeding with the ol'gals "down home" and those local mtDNA strands can go ahead and be mutated (randomly) and show up in all the locals in just a few generations.
We use this information to track and trace human expansion ~ but it takes "isolation" from all the other humans for this trick to work.
With these Cavebears the guy is telling us that they got isolated by humans as their numbers dwindled but the researchers found FEWER different mtDNA strands.
That information is contradictory. In fact, it indicates that one sort of Cavebear came to dominate the whole species, which would mean little, if any, isolation of one group of Cavebears from the other Cavebears.
In that case I would suspect that the Cavebears all died off fairly rapidly from DISEASE ~ maybe something like West Nile Virus.
We saw that happen with the crows in the Eastern United States. That one virus wiped out the vast flocks that used to fly around. Now we have crows coming back who are immune to the virus, but there still aren't many, and I just bet there are many fewer mtDNA lines among the crows in North America these days than there were before that plague.