Out of Africa: Startling New Genetics of Human Origins

[xchrom]

http://blogs.scientificamerican.com/talking-back/2012/07/26/out-of-africa-startling-new-genetics-of-human-origins/

***SNIP

Please describe the research that led to the paper that was published today:

We’re the first ones to look at these diverse groups of hunter-gathers in Africa who descend from some of the most ancestral lineages in the world. They’re interesting because they have very unique and distinct lifestyles There are few populations that maintain this active hunter-gatherer lifestyle.

This is the most extensive study in Africa using high-coverage deeply detailed sequence data. We focused on three groups because they’re anthropologically interesting. They’re thought to be descended from groups that are ancestral to all modern humans. We wanted to understand the genetic basis of adaptation to their local environment including, for instance the short stature trait in Pygmies.

So what did you find?

We discovered 13 million variants and, of those variants, greater than 3 million are completely novel, meaning that they have not been reported in any database. The current public database has 40 million variants. So we found 3 million novel variants by simply sequencing 15 individuals. That increases by about 8 percent all known human genetic variation. It also demonstrates that we’re missing a lot of really important variation that’s out there, particularly in Africa, which is the homeland of modern humans and a place where there’s been a lot of time for differentiation to have occurred in very diverse environments. What this means is that there’s s probably a lot of regional or population-specific variation out there that has not been that well characterized, some of which is functionally very important.

[alfredo]

1. Knr

[struggle4progress]

2. Genetic Data and Fossil Evidence Tell Differing Tales of Human Origins

By NICHOLAS WADE
Published: July 26, 2012 135 Comments

After decades of digging, paleoanthropologists looking for fossilized human bones have established a reasonably clear picture: Modern humans arose in Africa some 200,000 years ago and all archaic species of humans then disappeared, surviving only outside Africa, as did the Neanderthals in Europe. Geneticists studying DNA now say that, to the contrary, a previously unknown archaic species of human, a cousin of the Neanderthals, may have lingered in Africa until perhaps 25,000 years ago, coexisting with the modern humans and on occasion interbreeding with them.

The geneticists reached this conclusion, reported on Thursday in the journal Cell, after decoding the entire genome of three isolated hunter-gatherer peoples in Africa, hoping to cast light on the origins of modern human evolution. But the finding is regarded skeptically by some paleoanthropologists because of the absence in the fossil record of anything that would support the geneticists’ statistical calculations.

Two of the hunter-gatherers in the study, the Hadza and Sandawe of Tanzania, speak click languages and carry ancient DNA lineages that trace to the earliest branchings of the human family tree. The third group is that of the forest-dwelling pygmies of Cameroon, who also have ancient lineages and unusual blood types.

The geneticists, led by Joseph Lachance and Sarah A. Tishkoff of the University of Pennsylvania, decoded the entire genomes of five men from each of these groups. The costs of whole-genome sequencing have fallen so much that the technique can now be applied to populations for the first time, said Dr. Tishkoff, who paid the company Complete Genomics around $10,000 for each of the 15 genomes ...

http://www.nytimes.com/2012/07/27/science/cousins-of-neanderthals-left-dna-in-africa-scientists-report.html?_r=1&pagewanted=all

[xchrom]

3. +1