There’s a famous old anecdote about Charlemagne that’s been used for ages to explain how interconnected we are among our biological pasts. It has been said that everyone of European ancestry is related to Charlemagne, the great King of the Franks, born in 742 AD. If you’re European, you’re royalty. How is that possible?
I’ll tell you another tidbit first: Not only do all Europeans share Charlemagne as an ancestor, they share everyone alive at the same time as Charlemagne as an ancestor. Everyone who had kids, anyway. Let me explain:
Everyone alive has two biological parents. They each have two parents themselves, for a total of four grandparents. For x number of generations that you travel back in time, you have 2^x direct grandparents of increasing separation. Extrapolate that back to Charlie’s time, and you’d need 1 trillion grandparents to cover all your ancestral bases. Michael from Vsauce did a video about it. Since that’s far more people than have ever been alive, we need to engage some incest to solve the problem. Not banjo-applesauce incest, just a bit of redrawing our family trees into family webs.
Somewhere, far enough back in the web of grandparents, we will find a person whose lines connect to every single person who comes after them. That zig-zagged trail of shared genetic history ends surprisingly recently (for Euros, again): A common European ancestor around 1400 AD. Go a bit farther, and we find a common Earthling ancestor around 3,000 BC. It’s neat stuff. But it’s all based in mathematical models, not real genetic data.
Until now. USC and UC Davis researchers Peter Ralph and Graham Coop have surveyed the genomes of 2,257 Europeans in order to put some real data behind those models. Because of the random shuffling of chromosome fragments that created your father’s sperm and your mother’s egg, you, your siblings and your cousins all share varying chunks of DNA. People who are more closely related share more of these chunks. Depending on how many chunks are shared between two people, we can calculate their approximate relation to each other. Using 2 million shared sequences and a lot of math, they proved the mathematical models correct. Turkish people are more related to other Turks than to someone from Portugal, but they are related enough that, not only do they share one common ancestor a few hundred years ago, but they share every ancestor if you go back a mere thousand years. The models guessed that a long time ago, but now we have the data to prove it.It’s likely that these patterns extend to other regions of Earth, although the numbers might be slightly (but not that) different.
Next time someone in your neck of the ethnic woods points out a famous relative or claims blue-blood descent, remind them that they aren’t so special. All street-sweepers are royalty, all nobles are peasants, and we are all Kings.
Read more at NatGeo. Have more questions? Also check out the great FAQ on the project from the researchers themselves.