Here’s our basic human story based on genetics. 60,000 years ago there was drought in Africa brought on by an ice age to its north. The human species lived only in Africa and had dwindled to perhaps 2,000 individuals. They looked like the San people of West Africa. The drought drove some of these Africans into the Middle East where three key migrations took place:
- The first migration hugged southern coasts all the way to Australia and accounts for the Aborigines of Australia.
- One arched northeast, then branched again, some people moving down into India, others going southeast to Asia, and still others going north into central Asia.
- One went west into southern Europe.
Based on the genetic evidence, not one group of humans 50,000 years ago moved from the Middle East in the direction of northern Europe. It wouldn’t be until about 40,000 years ago that the central Asian human population, from which northern Europeans came, would branch.
One key central Asian branch would move northeast, following migratory herds of reindeer. They would ultimately find their way to the Americas. The actual number of people to have braved the route over the Bering Strait 10,000 years ago, moving down into Alaska, was perhaps no more than a dozen. This branch of central Asians is ancestral to Native Americans.
The other key central Asian branch would go west and became known in paleo-anthropology as the Cro Magnon people. They are the ones who painted the caves in France and are probably responsible for killing off, via war and competition, the Neanderthals (a cousin to Homo sapiens, but a different species). Cro Magnons are the ancestors of contemporary northern Europeans.
Here’s Spencer Wells, the lead geneticist who pieced this fascinating story together over the past 20 years, giving a TED talk about it:
Something I take from this talk:
- Mitochondrial Eve (the African woman who is the common ancestor of all humans living today) lived 200,000 years ago.
- Y chromosome Adam (the African man responsible “for all the Y chromosome diversity in the world”) lived between 60,000 and 142,000 years ago.
- The biblical Adam and Eve, living at the same time in Mesopotamia, therefore, never existed.
Here’s a bit more on genes and the Adam and Eve question:
One more takeaway: for our species, migrating and globalizing are natural. We are opportunists. We need new worlds to conquer.