On 31/07/2006, at 11:00 PM, Alberto Monteiro wrote:
Charlie Bell wrote:
We do now know that if Neanderthals interbred with modern people,
there are no traces of Neanderthal genes left in modern
populations.
Neanderthals have no genes in common with modern populations???
Are they from an entirely different biological line? Silicon-based
lifeforms?
Wilful misunderstanding for comic effect?
Sort of.
Rich should probably have said "uniquely Neanderthal genes" or
something. But I know what he meant.
I know what he means. I just don't understand _how_ can someone
take this step [that we are not descendant from the Neanderthals]
based on a DNA analysis of them.
That's not what was said at all. What was said was if we *interbred*
with them, no traces of their (unique marker) genes remains.
If we have genes in common with Chimpanzees [who diverged from
us 7 million years ago - please someone corrects me as I am
quoting from memory
About 3 - 5. Orangs split about 7mya, Gorillas sometime between those
two.
- not real memory, I don't claim to be so
old neither to have past-live experiences] it's not hard to
imagine that we have genes in common with Neanderthals.
We have genes in common with spiders, sea squirts, and earthworms.
It's the genes we *don't* have in common that are interesting in the
case of working out ancestry and relationships.
So how can a DNA test prove that they are not [a part of] our
ancestors?
They probably are. Modern man seems to have evolved out of a group of
Neanderthals. The question was whether they interbred after the
split, and a DNA test can't prove that they didn't. But there's no
traces left of their genes, if they did. It's fairly easy to show
with modelling or computer simulation how quickly genes can be either
fixed or eliminated in a population, I recommend "Evolutionary
Genetics" by John Maynard Smith if you're particularly interested.
Can't find my copy, though, which is irritating me.
Charlie
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