Thursday, 8 February 2018

My Inner Neanderthal

One of the aspects of autosomal DNA testing that I find most fascinating and fun is my Neanderthal admixture. It is one of those things that really are meant "just for fun"; however, for me, it has sparked some deep reflections.

A couple of years ago, scientists determined that all non-African humans living today have some DNA inherited from Neanderthals, which means that they (we) are literally descended from mixed unions between early modern humans (homo sapiens sapiens) and Neanderthals. In addition, certain groups in Eurasia have been shown to possess DNA from another recently discovered group of archaic humans, known as Denisovans. Africans have no Neanderthal DNA - except for those Africans who have non-African (e.g. Arab etc.) ancestry - but seem to have inherited genes from other groups of archaic humans in Africa of whom little or nothing is presently known.

In other words, none of us are pure homo sapiens sapiens; we're all hybrid beings to a greater or lesser extent. For Europeans and Asians, the average amount of Neanderthal DNA is between 1% and 4%.

I've got my Neanderthal DNA estimates from two companies: 23andMe and WeGene. In fact, WeGene analyzed my uploaded 23andMe file, so the calculations are actually based on the same raw data.

23andMe

My initial Neanderthal report from 23andMe looked like this:


As you can see, it shows that I have an estimated 2.8% Neanderthal DNA, which is above average for European users, but still within the normal range of 1%-4%.

After the 2016 upgrade to the "New Experience", 23andMe doesn't report Neanderthal percentages anymore, only the number of Neanderthal variants detected. Here is mine:


I'm still above average, more specifically within the top 12% of all 23andMe customers.

They also gives you a chromosome map of exactly where your Neanderthal variants are located, kind of like an ethnicity chromosome painting:


WeGene

WeGene's Neanderthal report is very straightforward: They give you your percentage, and that's it.


The number is very precise, but the impression of extreme accuracy is probably false. No admixture estimate can be taken literally down to the third decimal digit. I choose to read WeGene's estimate as "approximately 3.2%".

Interestingly, this is almost exactly the amount of DNA one would expect to inherit from a great-great-great-grandfather. In other words, according to WeGene, I am genetically 1/32 Neanderthal!

Them and us, them and me

It's mind-boggling to think about how these ancient Neanderthal genes have been passed down within populations to the extent that they still show up today in amounts like mine (and numerous people have even more than me). When I stop to consider what a number like 2.8% or 3.2% really means, it does make me feel more connected to my Neanderthal roots. It makes me curious about how they were similar and different to me and to everyone else living on this planet today. It makes me curious about the nature of those mixed relationships that brought the two different branches of the human family tree - and my personal family tree - together all those millennia ago.

The more we learn about the Neanderthals, the more we understand that they were not really that different from ourselves. They were intelligent and capable in their own ways. They made music. Recent research has found that many modern humans have inherited actual physical and mental traits from their Neanderthal ancestors, including skin tone, hair colour, sleep patterns, mood, etc. I wonder what parts of my personality can be attributed to my Neanderthal ancestors. If I could travel back in time to meet one of them, would we have recognized something of ourselves in one another?

What does "extinction" imply? Knowing that many of us still carry their DNA inside us, can we really say that the Neanderthals are extinct? If I can say that I am part Forest Finn or part German, why can't I say that I'm also part Neanderthal? I have more Neanderthal DNA than I have Finnish or German DNA in me. The connection lies 20,000, 30,000, perhaps 70,000 years back in time, but is part of my body - and probably my mind - in a very direct and almost tangible way at this very moment.

Some might find it strange, but I actually do feel part Neanderthal. What it really means, I'm still figuring out.

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