I watched it with some friends on Saturday night and it was the first movie in a long time that caused so much discussion.
Here's the summary: by analysing the Y chromosome of people from around the world researchers were able to build a tree / map of how people migrated over time. Breifly:
Until 50,000 years ago, everyone was chilling in Africa
Drought caused by the looming ice-age drove one group of people to follow a coastal route through India and to Autstralia.
About 40,000 years ago, there was a big branching out of people from central asia - two groups moved east to China, one group moved down to India. Another group headed far north-east.
From the north-east, one group returned west to beome europeans and the rest trudged on eastwards in the arctic circle.
About 10,000 years ago around 20 people survived the crossing across Beringia (the land mass that was exposed when the Bering Strait water levels were low). Within 800 years they multiplied and inhabited the whole American continent.
That means that, only about 2000 generations ago, our ancestors were all buddies, chilling in Africa.
The documentary is a little slow but seeing portraits of people around the world makes the similarities so apparent - it's definitely worth watching.