My wife was intrigued by a statistician’s writing that if you go back 3400 years, we’re all related. Not actually surprising if you think about it. After all, you’ve got two parents, four grandparents, eight great-grandparents . . . that’s exponential progression and it’s mathematically powerful.
My previous partner’s nine-times-great-grandfather was Roger Williams (founder of Rhode Island). But she had a lot of forebears in that generation — over 2,000. Go back twenty generations and it’s over a million. That’s only around 500 years. Go back a few centuries more and the number of your ancestors exceeds the entire human population.*
How could that be?
Family trees are not rigid lineages separated from each other. To the contrary, they are all tangled together. Your ancestors were of course not yours alone, but the ancestors of countless other people. And those long-ago ancestors with innumerable modern descendants likewise share those descendants with similarly huge numbers of other forebears.
That suggests you are indeed related to every other human being; a cousin many times removed.
But you may have to go pretty far back for that link. Because while our lineages are tangled together, it’s not random, there is a lot of segregation, notably geographic, among genealogies.
Though there has of course been mixing of disparate segments of humanity, for most of history people in a given geographic locale had limited opportunities for mating with foreigners. So someone like me, with European Jewish ancestry, might have a hard time finding a common ancestor with a Bornean. Yet on the other hand, with each of us having millions of ancestors, a single match is not implausible.
Humanity’s more distant antecedents also show our relatedness. There were many different “homo” species, but all except one went extinct. And the environmental challenges that defeated all those others nearly did us in too. Apparently at some point there was a “bottleneck” that only a very small group managed to scrape through — ancestors of all modern humans. In fact, scientific DNA analysis suggests we may all have descended from a single woman in that band. Her name was Eve.
Going back further, our closest related species is the chimpanzee, with whom we shared a common ancestor around six million years ago. Our DNA is 99% identical to chimp DNA. Among all humans DNA is 99.9% the same.
We are in fact related to every other living thing. Mouse DNA is around 90% identical to ours. Go back to your millions-of-times-great-grandpa and he’s a fish.
DNA tests give ethnicity percentages. For American Blacks, there’s typically a high percentage of West African, but also a significant percentage of northern European. For obvious reasons. I never did a test because I’m pretty sure it would come back almost 100% Ashkenazi Jewish. I’d be shocked if it said something like 12% Cherokee. Though again, somewhere along the line, some other DNA might have crept in there.
My wife’s forebears all came from Ireland. But she queries what it really means to say she’s “Irish.” Questioning whether there’s really any such thing, given Viking incursions and so forth, and again that all our DNA is 99.9% the same anyway. But calling someone “Irish” can mean merely that their not-too-distant forebears were born there.
As to that 99.9% human DNA identicality — the variations within any human subgroup (like “Blacks”) actually outstrip variations between such groups. Yet DNA — which is a string of many thousands of molecules of which there are just four variants, labelled A, C, T and G — does contain sequences which can be identified as unique to particular subgroups.
Thus if I am (mostly) genetically Ashkenazi, that’s a biological difference from a person who has little or no Ashkenazi DNA. Likewise for someone “Irish.” But it’s very important to say that it’s entirely up to us what significance, if any, we place on such differences. Perhaps the answer should be “very little,” given again the 99.9%.
But human life is not that simple, and maybe an even better option is to make the differences something positive. Culture is more important than biology. It’s the cultural differences that really matter; and we can embrace, even celebrate, our human cultural diversity, enriching and strengthening us. That’s how I see America.
I call myself an American rather than a Jew. I don’t follow the Jewish religion, nor even see myself as part of the related culture. Rather, always steeped in history, I see myself as embedded in the great global human project, as my prime source of meaning. And yet my particular ancestry does have a part of that meaning. I’m mindful how it fits in the bigger picture and illuminates it. And how it shaped my own life. For my grandparents and mother in Nazi Germany, Jewish identity was not something they could set aside.
* At 100 generations — before you even hit the 3400 year mark — the number would contain 31 digits.
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