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Modern Humans, Neanderthals Shared Earth for 1,000 Years
joffley writes "ABC News is reporting on new evidence that has emerged suggesting Neanderthals co-existed with anatomically modern humans for at least 1,000 years in central France, before gradually disappearing about 28,000 to 30,000 years ago. But why did they disappear?"
What is the mechanism by which genes fade? I suggest that you take a basic biology class. Mitochrondrial DNA tests indicate that Neanderthals were an entirely seperate species with no interbreeding.Here's more on MtDNA highlight the discovery of Eve who lived 200,000 years ago.
Thalasar
Actually, this merely says that any Neanderthal ancestors we may have weren't through the pure-maternal line. It says nothing at all about the nuclear DNA, which is over 99% of our DNA.
True, however:
My guess is that we'll never have good enough evidence of Neanderthal genes to show that there was no interbreeding at all. That requires study of the entire genome, and the fossil record doesn't have to have preserved it for us.
No - there would be a distinctive signal we can detect purely from modern human genomes. Imagine that for gene X, 1% of Europeans have a Neandertal gene, and everyone else (including all non-Europeans) have the Sapiens gene. We sequence this gene from 10000 people, 1000 of whom are European, 10 of whom have the Neandertal gene. Those 10 Europeans have sequences which are similar to each other, but are much more different from the consensus than any other gene sequences - and most significantly, much more different than any of the African samples. (Africa being the homeland of Homo Sapiens means it has the largest genetic variability.)
Putting it another way: if we created a phylogenetic tree of the genes, we would observe some of the European genes being basal (separated from the bulk of the sequences by the first bifurcation on the tree), and by a large margin (after this bifurcation, there is a long time before the next bifurcation on the main branch.)
We haven't yet observed such a pattern, although I think people have looked. We may yet find this, but the longer we look without finding it, the less likely the interbreeding hypothesis becomes.
IAATMP. (I am a theoretical molecular phylogenist.)
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I'm sick of people touting Intelligent Design when they don't even understand Evolution.
Evolution is NOT about "random mutations". There is nothing at all RANDOM about evolution. Sure, there are random mutations going on all the time, but that's not what evolution is about. Evolution is about NATURAL SELECTION which is definitely NOT a random process.
There is a very specific rule that is applied to the "random mutations" to see which ones move forward and that is (more or less) this: Those mutations that tend to make a creature at least slightly more successful will tend to spread throughout a population. And "successful" means (essentially) living long enough to reproduce and raise young.
This is NOT random at all. Most (nearly all) mutations are either BAD and cause damage, or effectively do nothing. Only a few rare mutations actually pass the natural selection test of being positive and therefore spread through successive generations.
In a given context a mutation is either going to tend to be helpful to the survival of the creature or not. So I say once again Evolution is NOT random.
I could go on and on and explain how natural selection often leads to results that APPEAR to look "planned", even though they were not planned with any intelligent forethought, but that would be a whole book. Instead, read Richard Dawkins "The Blind Watchmaker".