Your Family Tree, Reconsidered

Thinking about: Your ancestors

You have almost certainly met your direct ancestors, including your parents, grandparents, and (maybe) your great- and even great-great grandparents. You might also have undertaken a project to fill in your family tree. A decade ago, I did this and soon realized what a challenging task it was.

This is because each generation you go back, your workload doubles: You have two parents, four grandparents, eight great-grandparents, and so on. Go back ten generations and you have 1,024 great- ... -great grandparents. Go back thirty generations—about a thousand years—and you have a billion direct ancestors, which is kind of strange since there were only about 300 million people on the planet at that time. (I untangle this paradox in my book You: A Natural History.)

This increase in workload would be bad enough, but it is compounded by the fact that the farther back you go, the less reliable your ancestral information becomes. Realize, too, that even if you somehow have access to reliable birth records going back for centuries—as might be the case if you’re of royal blood—there is still an element of uncertainty. Yes, you can find King John and Queen Jane on your family tree, but was King John really the father of “their” offspring? These challenges were sufficient to make me abandon my research only a few generations back.

Science has given us a shortcut for tracing your ancestry. Send a genetic testing company a sample of your saliva, and it will analyze your DNA. In the report it subsequently returns, you won’t get your family tree. You will instead be informed where your ancestors lived. You might be told, for example, that your DNA is 99.4% European and 0.6% East Asian and Native American. You might also be informed that 15.9% of your European ancestry was Welsh, with Gwynedd, a county in northwest Wales, being an ancestral hotspot. You should, however, view these results with a degree of skepticism. In particular, it is unlikely that genetic tests can ascertain a person’s Welshness to within a tenth of a percent or trace it back to a single county.

Why, then, do genetic testing companies report such results? Because doing so makes them seem more “scientific.” Also, by focusing on a particular country or portion of a country, they increase the results’ appeal to test-takers. For one thing, they provide people with a loom on which to weave stories about their ancestors. The results also can be used to explain their personality traits: “Of course I like to sing: My ancestors were Welsh.” And finally, the results might justify making a pilgrimage to their “ancestral land, the beautiful hills of Gwynedd.”

Suppose that the results of your genetic test were in fact reliable. Suppose, in particular, that you were able to trace your family tree back to the Gwynedd region of Wales and discovered that 500 years ago, nearly all of your direct ancestors lived there. (It is, I know, highly unlikely that anyone could do this, but bear with me.) Even then, your ancestral research would not be complete. You would, after all, immediately be confronted with the question of where these Welsh ancestors came from.

They couldn’t simply have popped into existence in Wales. Indeed, archeological evidence suggests that humans took up permanent residence on the British Isles only about 11,000 years ago, at the end of the most recent Ice Age, and that they came there from the European mainland. (At that time, by the way, they would have been able to walk there because sea level was substantially lower than it currently is.)

Archeological evidence also suggests that your mainland European ancestors themselves came from Africa. At the end of the 20^th century, the scientific consensus was that humans evolved in the East African Rift Valley, which runs through what are now Ethiopia, Kenya, and Tanzania. Early in this century, however, the pan-African hypothesis emerged. The idea was that although humans were evolving across Africa, the Rift Valley just happened to be conducive to the preservation of human fossils. By telling you that your ancestors are, say, Welsh, a genetic-testing company is simply picking an arbitrary point in time as your ancestral origin.

If you want a deep and science-based analysis of your ancestry, I am happy to provide one. To do so, I don’t need a saliva sample from you, a picture of you, or information about where you live. Also, I won’t charge you for my analysis—although it would be wonderful if you became a paid subscriber to my Substack.

Okay, drum roll! Here is my analysis: If you are a human, you are ultimately of 100% African ancestry! And by the way, your ancestors likely moved around a lot.

Need more food for thought? Click here for my past essays, listed by title. Want to listen to rather than read my essays? Click here for narrations of my essays on becoming a Thinker, and click here for narrations of my essays on “applied thinking.” Narrations of my essays on becoming a Thinker are also available on your favorite podcast app. To play them, open that app and search for “Thinking More and Better,” and add episodes to your playlist.