"Dr. Spencer Wells, a 33-year-old geneticist, has closed the door on his laboratory and is embarking on the biggest adventure of his life. His mission: to retrace the most extraordinary journey of all time, a journey that involves every man, woman and child alive today."
Basically, what they did was track dna across the planet, to see where people came from and what paths they took. What they found wasn't shocking, but it was really fascinating to watch the trip - he started in Africa (I missed that part, sigh) and found that man, as a whole, had made two separate migrations due to necessity - droughts and famines and the like.
One group headed east along the coast and eventually ended up in Australia, forming the group we now call the aborigines. The other group traveled up, into central asia, and from there split - some of them heading north and west to become Europeans (he more or less ignored those) and the rest heading east, populating parts of Asia, including Russia and Mongolia, going to the far north, and eventually travelling over the (former) land bridge to Alaska and then down into the Americas.
It was really interesting to see, especially some of the "adventures" he went on, following the map their research had laid out for him. At one point he went north and found and travelled with, briefly, a group of Chukchi nomadic reindeer herders - really amazing people. The entire "village" was 9 people, who manage to survive in temperatures as low as -40 or -50 degrees C, whose very physical structure had changed to accommodate the temperatures - they were shorter, stockier, and had less surface area to their bodies, helping to keep them warm. They survived pretty much entirely off of their herd of reindeer - over 1000 in total - using them for food, transportation, building materials (the walls of their tents were reindeer hides)... and I'll be damned if they didn't look comfortable in that cold. That's the sort of cold that leaves people like me or you dead, frozen in a block of ice, our testicles withdrawn up between our lungs trying to find some warmth.
They had to ride old soviet tanks to get to them, after waiting for the skies to clear so they could fly up to the arctic circle, then take a bus 100 kilometers to the village where they were able to hop a ride another 100 km or so on some tanks, about 200 km into the arctic circle. It was rather mind boggling, and must've been an amazing experience.
Things like that boggle the mind, it's incredible what people endure, what they've been through - and the fact that just 2000 generations ago we were all one people, perhaps one family in a very literal sense. They estimate that less than 20 people survived the journey across the land bridge into North America - and those 20 people went on to populate all of the Americas, from the Navaho to the Mayans, all descended from 10 or 20 people who made the trip, thousands and thousands of miles, on foot, across some of the coldest and most barren terrain imaginable. It really is mind blowing.