Evidence that brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo

Proceedings of the National Academy of Science of the USA ^ | 2006-11-08 | Patrick D. Evans et al

[Lessismore]

Patrick D. Evans *, Nitzan Mekel-Bobrov *, Eric J. Vallender *, Richard R. Hudson , and Bruce T. Lahn *¶ *Howard Hughes Medical Institute, Departments of Human Genetics and Ecology and Evolution, and Committee on Genetics, University of Chicago, Chicago, IL 60637

Edited by Henry C. Harpending, University of Utah, Salt Lake City, UT, and approved October 5, 2006 (received for review August 10, 2006)

At the center of the debate on the emergence of modern humans and their spread throughout the globe is the question of whether archaic Homo lineages contributed to the modern human gene pool, and more importantly, whether such contributions impacted the evolutionary adaptation of our species. A major obstacle to answering this question is that low levels of admixture with archaic lineages are not expected to leave extensive traces in the modern human gene pool because of genetic drift. Loci that have undergone strong positive selection, however, offer a unique opportunity to identify low-level admixture with archaic lineages, provided that the introgressed archaic allele has risen to high frequency under positive selection. The gene microcephalin (MCPH1) regulates brain size during development and has experienced positive selection in the lineage leading to Homo sapiens. Within modern humans, a group of closely related haplotypes at this locus, known as haplogroup D, rose from a single copy 37,000 years ago and swept to exceptionally high frequency (70% worldwide today) because of positive selection. Here, we examine the origin of haplogroup D. By using the interhaplogroup divergence test, we show that haplogroup D likely originated from a lineage separated from modern humans 1.1 million years ago and introgressed into humans by 37,000 years ago. This finding supports the possibility of admixture between modern humans and archaic Homo populations (Neanderthals being one possibility). Furthermore, it buttresses the important notion that, through such adminture, our species has benefited evolutionarily by gaining new advantageous alleles. The interhaplogroup divergence test developed here may be broadly applicable to the detection of introgression at other loci in the human genome or in genomes of other species.

[ASA Vet]

Deliberate ignorance ping.

[dforest]

You know, I have decided that the chicken came first. But who made the chicken? Does anyone or has anyone ever been able to prove it or do they want to? Never will, I think. So they will keep coming out with theory after theory.

[blam]

"2) An oil company developed an amusing cartoon and billboard campaign linking oil to dinosaurs, which remained fixed in people's brains."

Sinclair Oil Company

"The original Sinclair Oil Company began marketing the apatosaurus (brontosaurus) in 1930 and now after more than 70 years, "Dino" still remains one of the most recognizable corporate logos in the world."

[HelloooClareece]

Microcephalin gene? Does this result in pinheads? This explains liberalism!

LMAO

[Physicist]

This meshes with the new creationist discovery that evolution == homosexuality.

[Born to Conserve]

Do you believe you are related to Micheal Jackson?

[Rurudyne]

The chicken was not a chicken even if the egg produced one.

A complementary dilemma respects the difference between canines (wolves & dogs) and vulpines (foxes). Canines have 78 chromosomes while vulpines have only 34. Following the science, I believe that vulpines have derived from canines after 24 fusions (where 2 chromosomes base pair become 1 base pair) and 2 fissions (where 1 becomes 2) ... if memory serves me right.

This means that the evolution of the vulpine from the canine involved many genetic mutations that did not result in sterility with respect to the population at large.

While this is possible (Petawalski's (sp?) horse with 68C and the domestic horse with 66C) it is not likely to always be the case (domestic horse with 66C and donkey with 64C are compatible ... but their offspring tend to be sterile).

The problem I see isn't one of evolution, but of population demographics. Canines, we are to believe, have been remarkably stable genetically while the vulpines––once they started on their merry way––need to have been genetically unstable enough to deliver fertile mutations like clockwork.

While that may be possible, the problem is that mutations tend to result in infertility or deformity and not healthy animals. So for each successful mutation that was able to sweep the whole proto-vulpine population there would have logically been others that resulted in localized population implosions ... and the speed of mutation would needs be increased as well.

Of course, in an isolated population group like the ones that give rise to pygmy animals one can easily see how mutations can accumulate without creating a diversity of species; however, as widespread as canines are the vulpines range even farther. They are the antithesis of an "isolated population group" which begs the question of why foxes are foxes even when they are from very different and widely separated population groups.

I've never got a satisfactory answer to that question.

[dforest]

Gotta laugh here. You got me! Cheers!

[edsheppa]

So it sounds like 70% of us are descended from a single common ancestor who lived 37,000 years ago?

Not necessarily. The proposed interbreeding might have been more general.

[Old Professer]

[paratrooper82]

Read my post #5

"Only if you believe in "evolution." Personally, I do not believe that I am related to, or a descendant from a monkey."

I DO NOT BELIEVE IN EVOLUTION.

[BLS]

"Evidence that brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo"


As someone that Jon Carry would consider stupid, I reply t this headline with a hearty, HUH?

(too many big words)

[Ruy Dias de Bivar]

Well, I guess I was wrong. In this town, the local station once carried all three brands of oil at different times.

[Old Professer]

I grew up in a very small town; gas pumps had glass tops with spinning balls.

[Lady Jag]

I don't see how we could have survived without archaic genetic 'seasoning.'

[muawiyah]

Well, that was a mistake on your part. Whenever men and women of any species get together, they party!!!!

In fact, it has not yet been demonstrated that modern humans and chimpanzees can't breed successfully.

[muawiyah]

Those ol'gals were up around 380 lbs.

[muawiyah]

No, you have it backwards. Moslems believe apes and pigs come from humans.

[muawiyah]

Splits and fusions within the realm of chromosomes though technically a sort of "mutation", do not require any gene mutations ~ which means that at the point where you started talking about "mutations" you steered right off the cliff into a pile of macacca.

[muawiyah]

I don't believe in monkeys. They are simply terribly deformed and handicapped human beings who leap around in trees.