In the Washington Post this morning. But more then just diversity, it shows "How we're all pretty much the same...". Hit the link, the whole article is great.
All three studies support the idea that modern human beings left East Africa, walked into Central Asia and then fanned out east and west to people the entire planet. The studies also confirm earlier research showing that as a group, Africans have more diverse genes than people of other continents. But the new research further shows that genetic diversity declines steadily the farther one's ancestors traveled from Addis Ababa, Ethiopia, which is roughly the site of the exit turnstile for the "out-of-Africa" migration.
The studies also show that many seemingly "purebred" ethnic groups have ancestry traceable to more than one continent.
For example, the Arabian Peninsula's Bedouin -- a culturally distinct group -- are descended not only from longtime Middle Eastern peoples, but also from Europeans and peoples originating from around modern Pakistan. The Yakut people of eastern Siberia share blood with East Asians, Europeans and American Indians, but very little with Central Asians, who are geographically closer to them than two of those populations.
The research may also shed light on the genetic underpinnings of human disease. One study found that Americans of European descent carry a larger number of damaging gene variants than African Americans do -- a byproduct of Caucasians' arduous march westward to the shores of the Atlantic.
The biggest message, though, is that these differences are the details, not the main message, of human diversity.
About 90 percent of the full catalogue of human genetic diversity exists in every human population. Individuals are likely to have almost as many differences with people we consider to be "like us" as with strangers on the other side of the world.
With such diverse and abundant starting material, the researchers were able to sketch a picture of ethnicity far more detailed than previously known.
For example, Africa's surviving hunter-gatherers -- two groups of pygmies and the San people of southern Africa who were formerly known as Bushmen -- are closely related to one another and quite distinct on a genetic basis from all other black Africans. The Hazara of Afghanistan and Pakistan and the Uygur of northwestern China are also close genetic relatives, despite living far apart. On the other hand, China's dominant ethnicity, the Han, is actually two genetically distinct groups, the northern and the southern Han.
The research shows that populations' genetic footprints on the planet are deep, sharp and not easily covered over by time.
Both research teams using the French DNA collection found geographic distance from East Africa is a major determinant of genetic differences among groups.
"Each group carried only a subset of the genetic variation from its ancestral population. So there is a loss of genetic diversity with the distance from Africa," Rosenberg said.
They found that the average person carries at least 2,000 SNPs that change the meaning of a genetic "word." However, in the European Americans, a larger proportion of those changes were likely to be unhealthy or unfavorable.
The reasons for this curious finding are not fully known, although there are theories.
The chief explanation is that the ancestors of Europeans (and most white Americans) suffered repeated population "bottlenecks" in which their numbers crashed as result of epidemics, environmental catastrophes and genocide. Each time that happened, the population lost a lot of its genetic diversity simply because a lot of people died.
The survivors, like their ancestors, carried a certain random collection of deleterious SNPs -- genes that caused disease or increased the risk of disease. When the population rebounded, those genes were spread widely as the small number of survivors gave rise to all living descendants.
But if they were potentially bad, why weren't they flushed out by natural selection? That is the mystery.