DNA analysis through The Genographic Project has implied the existence of our earliest identifiable male ancestor: a man (M168) who lived in or around the Great Rift Valley of Ethiopia, Kenya, and Tanzania some 45,000 years ago. The total population of Homo sapiens, all of them in Africa, was perhaps 10,000. Hunters and gatherers with no permanent home, these early humans were constantly on the move, following the herds of animals across the grasslands of north Africa. Until the climate changed, bringing warmer temperatures and rising sea levels and closing the land bridge to Asia a few millenia later, a number of people would leave Africa, but only the descendants of this "Eurasian Adam" would survive, making him the ancestor of all non-Africans.
Some 200 generations later, a second genetic marker arose with one of his descendants, a man (M89) who was born in North Africa or the Middle East around 45,000 years ago. Over thousands of years, his descendants, who account for as much as 95% of the world’s non-African population, followed the big game and expanding grasslands out of the Middle East into the steppes of Asia and eastern Europe. Some of his descendants, moved north through Anatolia and into the Balkans, adapting from familiar grasslands to forests and mountains.
Around the onset of the last ice age some 21,000 years ago, a man was born in Asia Minor or the Balkans with a new genetic marker (M170). This paleolithic ancestor was progenitor of geneticHaplogroup I and ancestor of about one in five of all Europeans.
As the ice sheets covering much of Europe began to retreat around 15,000 years ago, his descendants likely played a central role in re-colonizing northern Europe. It’s possible that the Vikings descended from this line.
http://s1.zetaboards.com/anthroscape/topic/2687046/1/ Prehistoric migrants spread farming in Europe. Researchers used DNA taken from the remains of farmers who worked the land more than 7,000 years ago to discover that they were not related to the hunter-gatherers who inhabited Europe previously. Instead, they probably belonged to an immigrant population, possibly from south-eastern Europe.The study also found that the ancient hunter-gatherers do share their predominant DNA type with some modern Europeans, unlike the agriculturalists who arrived in Europe at a later stage. Neither group, however, explains the genetic make-up of much of Europe’s current population, which indicates that there were other waves of prehistoric migration that still remain uncharted.
Humans first arrived in Europe 45,000 years ago, replacing a Neanderthal population. A series of major climactic changes then ensued, including the last Ice Age. Hunter-gathering helped humans to survive through that period and was still in evidence 11,000 years ago, as the Ice Age ended. Within a few thousand years, however, it had largely disappeared, as the new wave of immigrants settled and domesticated plants and animals. The study suggests that these farmers settled first in the Carpathian Basin. "It seems that farmers immigrated into Central Europe about 7,500 years ago, initially without mixing with local hunter-gatherers," Dr Barbara Bramanti, from Mainz University, said. "This is surprising, because there were cultural contacts between the locals and the immigrants, but, it appears, no genetic exchange."
Farming itself is believed to have begun in the Fertile Crescent of the Near East, between 12,000 and 7,000 years ago. Early communities there began to produce the so-called "founder crops", such as wheat and barley. More recently, it has become clear that early Chinese communities domesticated their own grains, such as rice and millet, independently of western influence and a growing body of research suggests that these methods may also have spread to the West.