the mystery ‘Denisovan’ people

 

Well, DNA is unravelling some odd information.

I know some DNA tests indicate a small percentage of Neanderthal in modern people. What? Neanderthal? Are you kidding? Maybe that’s why I refuse to be vegetarian…I just love meat! ha ha! That’s what I said in an email to my sister, who asked about this.

So, I got together with people that know more than me and asked around. There are two basic answers that I got from experts. First of all, that Neanderthal DNA is claimed from one company, and not all companies or DNA experts agree. So take it with a grain of salt. It may mean nothing. Some call it just a theory. (In other words, they don’t know.) But anthropologists argue we DO have Neanderthal in us. At least, some of us do. So, it is true that modern humans and Neanderthal mated many years ago.

Well, even if it is true…OK, here was my question…If we get 50% of our DNA from each parent, and 25% from each grandparent, and 12.5% from each great grandparent…you get the idea. In just a handful of generations, we get less than 1% from an ancestor and that’s just within the last 150 years or so. That’s the way autosomal DNA works.

Then why would Neanderthal show up with 1% when that goes back literally thousands of years? I mean, the math just doesn’t work out! I’m down to around 1% from each 4th great grandparent. An “average generation” is considered to be around 25 years, so 4th great grandparent goes back only 125-150 years. Neanderthal goes back thousands of years. The math really just doesn’t work out! Wouldn’t Neanderthal DNA be approaching zero, or even be completely washed out by now?

We modern humans are Homo Sapiens. Neanderthals were completely different. OK, we know they probably got together and interbred. In fact, anthropologists confirm this for us with science. But why would any of their DNA be in us today, thousands of years later?

It was explained to me that Neanderthal DNA and great great grandparent DNA (autosomal DNA) do not work the same. For some reason, the Neanderthal DNA from many thousands of years ago got really mixed up with our DNA, and has been passed down for thousands of years. It actually changed our DNA and stuck around. It is, what you might say…permanent. Why this happened, no one knows.

Furthermore, DNA is tricky. Some DNA, like autosomal DNA, does literally get mixed up like a deck of cards. So that’s why the percentages work out like 50, 25, 12.5 percent, etc. for autosomal DNA.

But there are other forms of DNA. Y-DNA for example, which only males have, is passed on from father to son, virtually unchanged, for hundreds, or perhaps thousands, of years. Mitochondrial DNA is similar, but passed down from mother to daughter, also virtually unchanged for thousands of generations. (Mitochondrial DNA is actually passed down from a mother to all of her children, but only the daughters pass it on to their children, the sons do not pass down mitochondrial DNA to any of their children.)  So, the theory goes, if we do actually have Neanderthal DNA in us, it worked more like Y-DNA or mitochondrial DNA, instead of like autosomal DNA. And so a small percentage got passed down to us, and still shows up many thousands of years later, virtually unchanged.

That’s what a few experts told me at a genealogy conference.

But then, I read stories like this on the internet news.  The headline is, our ancestors mated with the mystery ‘Denisovan’ people — twice. And furthermore, the Denisovans were unknown until 2010.

Well, suffice it to say, scientists are still making discoveries. In other words, we don’t know everything.

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