Posted on 11/07/2006 7:27:55 PM PST by Pharmboy
Neanderthals may have given the modern humans who replaced them a priceless gift -- a gene that helped them develop superior brains, U.S. researchers reported on Tuesday.
And the only way they could have provided that gift would have been by interbreeding, the team at the Howard Hughes Medical Institute and the University of Chicago said.
Their study, published in the Proceedings of the National Academy of Sciences, provides indirect evidence that modern Homo sapiens and so-called Neanderthals interbred at some point when they lived side by side in Europe.
"Finding evidence of mixing is not all that surprising. But our study demonstrates the possibility that interbreeding contributed advantageous variants into the human gene pool that subsequently spread," said Bruce Lahn, a Howard Hughes Medical Institute researcher at the University of Chicago who led the study.
Scientists have been debating whether Neanderthals, who died out about 35,000 years ago, ever bred with modern Homo sapiens. Neanderthals are considered more primitive, with robust bones but a smaller intellects than modern humans.
Lahn's team found a brain gene that appears to have entered the human lineage about 1.1 million years ago, and that has a modern form, or allele, that appeared about 37,000 years ago -- right before Neanderthals became extinct.
"The gene microcephalin (MCPH1) regulates brain size during development and has experienced positive selection in the lineage leading to Homo sapiens," the researchers wrote.
Positive selection means the gene conferred some sort of advantage, so that people who had it were more likely to have descendants than people who did not. Lahn's team estimated that 70 percent of all living humans have this type D variant of the gene.
"By no means do these findings constitute definitive proof that a Neanderthal was the source of the original copy of the D allele. However, our evidence shows that it is one of the best candidates," Lahn said.
The researchers reached their conclusions by doing a statistical analysis of the DNA sequence of microcephalin, which is known to play a role in regulating brain size in humans. Mutations in the human gene cause development of a much smaller brain, a condition called microcephaly.
By tracking smaller, more regular mutations, the researchers could look at DNA'S "genetic clock" and date the original genetic variant to 37,000 years ago.
They noted that this D allele is very common in Europe, where Neanderthals lived, and more rare in Africa, where they did not. Lahn said it is not yet clear what advantage the D allele gives the human brain.
"The D alleles may not even change brain size; they may only make the brain a bit more efficient if it indeed affects brain function," Lahn said.
Now his team is looking for evidence of Neanderthal origin for other human genes.
"Next time, do a little research."
As an aside, in France, their humorous weekly newspaper is called "Le Canard Enchaîné" which literally means "the chained duck."
They picked up good brains and then didn't know what to do with them. That sounds peculiar at first, but I know lots of people like that.
There is much in what you say. It may well be that a superior brain size of Neanderthals conferred little advantage because they were stymied by an inability to articulate an advanced language well.
Only when a gene for advanced brain size got somehow correlated with other genes for brain complexity, and language skills and vocal structures could societal skills be properly passed on to the next generations.
If we were but a single lineage back through the mists of history to the dawn of creation, there would be little reason for various blood types. Yet we share some blood types with gorillas and chimpanzees, as well as much of the organizational structure of the Y chromosome.
Clearly nature competes, even within a successful species, for favorable characteristics, which may have been holdovers from very long ago.
Neanderthals are not a separate species. Both Modern Humans (Homo Sapiens Sapiens) and Neanderthals (Homo Sapiens Neanderthalis) are Homo Sapiens.
You got it.
Evolving Genes May Not Size Up Brain
Science News | 6-3-2006 | Bruce Bower
Posted on 06/04/2006 8:02:02 PM EDT by blam
http://www.freerepublic.com/focus/f-news/1643387/posts
I never surmised that Neanderthals were not a speaking species, but I am willing to use that contention, however ill-founded, as an allegorical explanation for their inability to compete successfully, and eventually triumph.
Something in their genetic makeup, or social construction, operated against them whether it was speech, memory, or even olfactory insufficiencies (of either type).
Or maybe the Main Stream was just against them.
I never surmised that Neanderthals were not a speaking species, but I am willing to use that contention, however ill-founded, as an allegorical explanation for their inability to compete successfully, and eventually triumph.Ah, allegory. Here's the quote from your earlier post:
It may well be that a superior brain size of Neanderthals conferred little advantage because they were stymied by an inability to articulate an advanced language well. Only when a gene for advanced brain size got somehow correlated with other genes for brain complexity, and language skills and vocal structures could societal skills be properly passed on to the next generations.Since the evidence is that Neandertal is ancestral to part of the Earth's population, it is pointless to speculate on reasons for their extinction.
So if the Neanderthal big-brain gene ensured our existence, how come the big-brain gene didn't ensure the Neanderthal existence? Scientific theories are *almost* as fickled as voters.
Not being argumentative for its own sake, but the beginning of the discussion was in reference to a single gene, and how it may have been transmitted.
My point was that this single gene, in its earliest configuration, may have conferred little advantage, but in subsequent mixtures it proved to have been a good investment.
That gene may have helped them get there physically, but would would not have helped them much competing on Jeopardy! (excpet on questions about roast duck and mango salsa).
But I guess that wouldn't hold for coordinating the actions of fat cells, I take it? A bigger brain needed for a larger body, but not a fatter body? Americans getting heavier lately and all that.
I was kinda hoping for something to ... explain ... yesterday.
The Neandertal EnigmaFrayer's own reading of the record reveals a number of overlooked traits that clearly and specifically link the Neandertals to the Cro-Magnons. One such trait is the shape of the opening of the nerve canal in the lower jaw, a spot where dentists often give a pain-blocking injection. In many Neandertal, the upper portion of the opening is covered by a broad bony ridge, a curious feature also carried by a significant number of Cro-Magnons. But none of the alleged 'ancestors of us all' fossils from Africa have it, and it is extremely rare in modern people outside Europe." [pp 126-127]
by James Shreeve
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