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.

[PJ-Comix]

Who you calling a HOMO?

[JimRed]

Whenever men and women of any species get together, they party!!!!

Homos can't breed. Refer to sarcasm tag.

[muawiyah]

They what? Fur Shur they got some of them guys will handle anything.

[Thumper1960]

Thought that was Sinclair Oil.

[Ruy Dias de Bivar]

You are correct. Our local station carried all three brands at different times. I remember the dino on one of them.

[Rurudyne]

Not precisely true. Take the instance of the Petawalksi's horse and the domestic horse, for example.

The fusion of on two base pairs from the one seems to have occurred in historic times, and the two are compatible with few fertility problems. A mating results in an animal with 65C where one domestic horse chromosome is the same as two in the wild pony.

As a result of this fusion the domestic horse has become similar enough to an older branch of the family, the donkey, to make it possible to cross breed (producing an animal with 63C); however, these are normally sterile because of differences between the genes.

The point that should be made is that even if a fusion is an otherwise harmless mutation (fissions would appear to be more problematic) there is still no multiplicity of canids with similar sexual function and behavioral tendencies between the canines and the vulpines. At least not as there is for the extended family that includes horses.

Given the range of these species, as well as the success of the basic design––even their response to domestication is similar given one Russian experiment––it would seem inexplicable that there are just those with 78C or 34C.

Again, there is no good explanation for this as far as I know.

[muawiyah]

No doubt the answer is in the electronic substrate ~ wherever that is.

[Sacajaweau]

We got on the chicken and the egg with my 11 year old granddaughter. She will no longer eat eggs...That led to teaching her what my grandfather taught me...candling.

[Diggity]

Probably just think alike.

Diggity

[Rurudyne]

Funny.

I always thought it was blowing in the wind.

Of course in Texas––Land of Tex-Mex and the Refried Bean––it's often an ill wind that blows.

Not that we have anything on the curry-eaters of the world. ^_^

[SunkenCiv]

GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach	join list or digest view topics view or post blog bookmark post a topic subscribe
Thanks Lessismore. Note: this topic is from 11/11/2006. Blast from the Past. Just adding to the catalog, not sending a general distribution. To all -- please ping me to other topics which are appropriate for the GGG list.