It seems that modern humans have something like 2% of their DNA from Neanderthals – varying of course. What exactly does this mean. We share above 98% of our DNA with chimps and 50% with most plants. So what is the 2%. It can’t be over and above our relation to chimps as that would put us over 100%. Is it of the differences between us and our closest relatives, the chimps, 2% of that is common with Neanderthals? That doesn’t sound like enough actually.
IMWTK
Self reported for forum change to GQ.
Moved per request.
It’s easier to calculate how much Neanderthal DNA an individual or a population has than to determine what that DNA is doing. So the first has been done (at least a first concensus seems to have been reached) and the second is just starting.
According to this, and its introduction here, the Neanderthal FOX2 gene, associated with speech, has not persevered in humans. But genes for skin and hair development have.
So maybe human with FOX2-N had difficulties communicating. Maybe. And maybe their hair and skin were better adapted for the Europe of the time.
Maybe.
It’s early days, still.
They’re working on it.
npr.org happens to have a fascinating article about this exact topic today. I recommend it.
Apparently, although an individual may only have 2% of Neanderthal DNA, lots of people have different chunks of Neanderthal DNA, to the tune of about 20% total still extant among everyone.
The most notable lingering physical attributes resulting from this apparently affect skin and hair.
If you want more, again I recommend the NPR article.
Roddy
Here’s the explanation of the methodology that 23 and me uses to determine the percentages of Neanderthal DNA. As far as I can tell - the document I linked to is very technical and I haven’t had time to study it…they use whole genome sequences from populations without Neanderthal or Denisovan DNA and then calculate the drift by using some sort of statisical triangulation.
https://23andme.https.internapcdn.net/res/pdf/hXitekfSJe1lcIy7-Q72XA_23-05_Neanderthal_Ancestry.pdf
BTW, I have 2.9% Neanderthal DNA which puts me in the 87th percentile.
On a more personal note, when my youngest son was taking a lab anthropology course he delighted the prof when he got a buzz cut. She had the whole class come look at what she described as his Neanderthal ridge.
No clue whether it’s caused by N-genes, of course. Could be recapitulated with regular genes. It’s not very prominent and runs about where a mohawk would.
Another interesting tidbit from this new analysis is that it seems the male hybrids were not very fertile. This was deduced because of the “the genes associated with the testicles in humans and the X chromosome were unusually empty of Neanderthal influence”, per one article I read. Not sure I follow the reasoning, but there it is.
I’m going to check out the NPR article. I wonder if this will be featured on “Science Friday” tomorrow.
All I’m asking about is this “easier” calculation of the percentage. Since we share 98% of our DNA with chimps, and I assume Neanderthals shared a similar percentage, how can we say an individual has only 2% or 10% or 29% Neanderthal DNA. Presumably the 98% that’s shared with chimps could all have come from Neanderthals.
Genes that came from chimps would not be considered Neanderthal for this purpose. Only genes that Neanderthals have that baseline (African) humans don’t, but that out-of-Africa humans do, count for this percentage.
If chimps and baseline humans have a gene, and Neanderthals also have it, it’s possible that it could have wandered into OOA humans along with more specifically Neanderthal genes, but there would be no way in the world to tell.
Also, the 98% commonality with chimps is a comparison of average chimps with average humans. Individual humans will have varying percentages.
For when it’s not today - http://www.npr.org/blogs/health/2014/01/28/267923336/neanderthal-genes-live-on-in-our-hair-and-skin
Here’s a thread I started over 10 years ago that asks a similar question as the OP.
I probably posted in that 10 year old thread …
But I find it amusing that I have said for YEARS that we have crossbred with Neanderthals, and been told that no we didn’t … so this is a huge amusing oops to me. Why yes we did seem to crossbreed with Neanderthals [and considering that the percentage of neanderthal genes shared has now crept up to a combined total of 20 percent] that 2-4% in many people makes me want to track down some of the scientists and blow them raspberries.
[especially when I can look at mrAru and see the barrel chest, slightly overlong forearms, small brow ridge and ‘bun’ and dark hair/blue eyes and now some of his health issues. ook.]
I’m not convinced. I think it’s more likely to mean that Homo Sapiens females did not find Neanderthal males attractive (and/or received adequate protection from them), and that Neanderthal Females did find Homo Sapiens males attractive (and/or did not receive adequate protection from them.)
I know I’ve read about Orangutan males taking over a troop and killing off the males and all the babies, in order to facilitate breeding with the new females. I think I’ve read about it in Mountain Apes as well? So why would we assume that this is a DNA-specific rather than an attractive or a behavioral result?
Could be. But we’re also relying on the popular press’s interpretation of this analysis, so it’s also possible they’re leaving something out.
Males of several kinds of social animals will kill existing babies when they take over a group of females from another male in order to bring the females into heat sooner, but since Orangs are solitary and don’t go around in troops you must have read that about some other species.
It might not have been a matter of female choice. When modern humans in tribal cultures raid neighboring tribes they may kill adult males and take females and children as captives/slaves. So if sapiens tribes sometimes took in female Neanderthals as slaves, the males may occasionally have produced offspring with them.
This is why I love the SDMB. Where else can I find out that I’m wrong about why I’m right? LOL! 
Ignorance fought, Colibri!
Does this only happen with social mammals? I thought that male bears would kill cubs in order to mate with female bears.
I know someone that looks exactly like the guy in the first picture. I wonder how much Neanderthal there is in him.
It depends on males continuing to be in the same area as the females for some time after the young have been killed, so the females have time to come back into estrus. So it’s going to be more common in social animals. I haven’t heard this about bears specifically, but I suppose it could happen where the female’s range is within that of the male.
Well, I could be wrong as my source is PBS Nature shows-- they’re usually pretty good, but hardly peer reviewed journal stuff. 