We’re all brothers and sisters under the skin — or at least distant cousins. According to the popular Single-Origin Hypothesis (the “Out of Africa” theory), the human race originated in eastern Africa something like 100,000-200,000 years ago. The alternative Multiregional Hypothesis (which seems less likely to me, but what do I know) says that Homo sapiens evolved independently in several places, but even then there were Homo habilis ancestors that evolved in Africa — the question is really which populations should and should not count as Homo sapiens.
That means that we share common ancestors. And no, you needn’t be one of the three million Irish descended from Niall of the Nine Hostages, or the sixteen million people worldwide descended from Genghis Khan. If you go back far enough, you’ll eventually hit the human race’s most recent common ancestor, some lucky breeder with billions of living descendants — possibly as late as the first or second millenium BCE. We can also imagine tracing back to Mitochondrial Eve and Y-chromosomal Adam — our most recent common ancestors through purely matrilineal and patrilineal lines, respectively. (Adam and Eve didn’t know each other; he lived 60,000-90,000 years ago, while she was perhaps 150,000 years ago.) The point is, if you follow your family tree backwards, it keeps branching into more and more ancestors, and eventually all of our individual trees get mixed together. So, for example, Bill O’Reilly and Michael Moore are distantly related, although the family reunions are likely a bit awkward.
An obvious question is: how did we get from there to here? How did human DNA mix and match, spread out through various locales and ethnicities, and focus together to create that pinnacle of biological achievement: you? Well, a new project from National Geographic, IBM, Spencer Wells, and the Waitt Foundation aims to find out: the Genographic Project (hat tip to Maria). They are collecting DNA samples from all over the world, and using genetic markers characteristic of certain populations to infer how humans migrated across the globe, cheerfully (or not so cheerfully, often enough) reproducing along the way.
Best of all: you can participate! Sadly, you have to pay ($100) to join the project, rather than receiving recompense for your services; but it’s pretty cool. You get a kit that allows you to take a sample of your own DNA and send it in for analysis. The results won’t tell you about your immediate family, but they’ll reveal the geographical origins of your deeper ancestry. C’mon, you want to know where your haplogroup originated, don’t you? And we need to hurry, before the intimate (as it were) interconnectivity of the global village scrambles our genetic markers once and for all.