https://www.reddit.com/r/interestingasfuck/comments/jy8fji/genes_are_everything/

For some strange reason this post on Cheddar Man has been very popular on Reddit today. It contains one of maybe many claims around him that we possibly could have addressed better a few years back. Rough and ready thread.

No not the claim that he was excavated ‘recently’ (he was excavated in 1903).

No not the claim that he is 9000 years old (I think this comes from an old uncalibrated radiocarbon date - the most recent calibrated date puts him at ~10,300 years old).

It’s the claim that Adrian Targett, a retired schoolteacher from the nearby village of Cheddar, is his direct descendant. This is based on mitochondrial DNA, a bit of DNA that is almost always inherited from your mother, giving a sense of your maternal lineage.

DNA work done back in 1999 found that Adrian Targett probably belonged to a maternal lineage know as U5. ‘Probably’ because this was never published properly so we can’t know for sure. The 1999 work, and another recent study found that Cheddar Man also belonged to the U5 lineage.

In 1999 (and apparently today as well...) this result was used to suggest that Adrian Targett was the direct descendant of Cheddar Man and that his family had an incredible 9000 year (or is that 10,000 year?) vintage in Cheddar.

Mensa members among you might already have spotted that this can’t quite be quite. Cheddar Man was male. Mitochondrial DNA is passed down maternally. So Adrian Targett couldn’t be a direct maternal descendant, but was he descended from a close female relative?

Probably not. Balance of probabilities says that it’s more likely they shared a distant maternal ancestor who lived potentially thousands of years before even Cheddar Man was born.

This is even more likely given the amount of genetic change there’s been in Britain over the last 10,000 years, influenced by several significant movements of people in prehistory and probably history too. It is unlikely any selected line of descent is unbroken.

Worth also saying that the haplogroup U5 is relatively common in Britain and large parts of Europe more generally. It’s likely there were other people in Cheddar, unrelated to Adrian Targett, who carried the U5 haplogroup, never mind millions in Britain and Europe more broadly.

So is Adrian Targett the direct descendent of Cheddar Man? Not based on the mitochondrial DNA.

And yet...

Each generation back your number of ancestors theoretically increases exponentially, except quickly you reach a point where you have more ancestors than there were people alive. Eventually you reach a point where everyone has exactly the same ancestors.

For Europe, this is the 10th Century AD. So if you have any kind of recent ancestry from Europe, everyone who lived in any part of Europe in 10th Century AD and who successfully passed on descendants is your ancestor.

(Incidentally you won’t have inherited DNA from many of these ancestors - once you get past around 10 generations ago the chances you have inherited any DNA from any one of your ancestors are vanishingly low).

For the whole world this identical ancestors point is counter-intuitively recent - 5000-15,000 years ago. So...it’s quite possible Cheddar Man lived before the identical ancestors point of all living humans.

So...if Cheddar Man did have children (he was only in his early 20s when he died), it’s likely he’s the ancestor of more-or-less everyone alive today.

So it turns out there’s a good chance Adrian Targett is in fact the direct descendant of Cheddar Man. As most of us are. No matter who you are.

More Context... https://twitter.com/bristolboy99/status/1330286023989993472

A related thread... https://twitter.com/graham_coop/status/613728995633315840

And a related more detailed blog post... https://twitter.com/Graham_Coop/status/1330295422590574593