After I graduated from college I taught 5th grade for a few years in a small town in North Carolina just above the border with South Carolina. Virtually all the students I taught, a third white, a third black and a third Lumbee Indian, had never left the county, had never gone to the nearest “big” town where there was a military base, and had certainly never gone to Raleigh, the capital. The big event one year for our 5th graders was a trip to the planetarium at the University in Chapel Hill. The three races had lived together in parallel without much mixing for many, many years, under the shadow of slavery and then Jim Crow. I will bet that the races have mixed much more since those days in 1972. Now consider an article in the 5/17/14 edition of Science News.
Ms. Saey reports on several studies of the DNA recovered from ancient remains, like Otzi above. He seems to have lived most of his life in southern Italy around 5300 BC but his body was found in the Italian alps. His DNA is found these days only in the populations of the islands, Corsica and Sardinia. Why he was in the alps hunting from where he resided is something of a mystery as is the arrow wound that caused his death.
Another fossilized remains from about 7000 BC in northern Spain showed a dark skinned blue eyed man, quite unusual. Other studies showed that hunter-gatherers and agriculturalists lived in the same areas for some 2000 years without much genetic mixing, and further that these samples taken from Spain, Italy, Germany, and Sweden show little similarity to modern day Europeans. Whoa! The neolithic population of Europe moved on and the modern population, who seem to stay close to home, show little overlap. Complicated. Eventually farmers and hunters began to intermarry (in a copper and bronze age sort of way) but still they contribute little DNA to the modern population of Europe. Further, as peoples moved in after the last ice age with different technologies, exemplified in their different potteries, they also tended to remain to themselves. The human clan or tribe would seem to be an insular organization. Thank heavens for modern mixing.
The article has more interesting features and I recommend it. One other study showed that Native Americans, Asians, northern Europeans, whether farmer or hunters, showed the influence of a previously unknown population, the ancient northern Eurasians. It is beginning to appear that humanity has many roots.