The Denisovan discovery thread

Not too surprised to hear this. Neandertals and Denisovans were more related to one another than they were to us. The genetics seem to show that the common ancestor of Neandertals and Denisovans came out of Africa(and split with our common ancestor) around 500,000 years ago. The finds in Atapuerca in Spain at around 350,000 years ago show this mix.

It seems in very basic terms that at some point there was an East/West split and the Western folks became Neandertals, the Eastern became Denisovans. An added complication was that at least once, if not a few times early Modern Human groups out of Africa wandered into the Middle East and got the groove on with the locals and added some of our DNA into the mix.

Though we don't know what Denisovans looked like, I suspect the Neandertal like fossils found in Asia(China mostly) were them. That they looked more Neandertal than Modern Human. Then again if you go back say 100 odd 1000 years ago, we look more like them too. We have a suite of features that mark us out as Moderns(large globular braincase, protruding chin, swept forward cheekbones), but they were not as marked as they are in people today. We had much larger brow ridges back then for a start. A few years ago a Wiki page on Neandertals actually showed a pic of an early Modern skull from Africa and it stayed unedited for ages, which kinda illustrates this

I would suspect that a Denisovan, or Neandertal, or Modern of that era, upon meeting one of the others, would beyond things like maybe different skin tones recognise them as being like them more than not. A modern of today would stand out far more. Actually I suspect that even though we're far more interrelated today the diversity of external physical features in people today across populations and geography might even be higher than back then. That say a 6th century African from the Congo who had never seen a European would get more of a shock at encountering a 6th century Swede - and vice versa - than a Denisovan would upon meeting a Neandertal.

gozunda wrote: »

Observed differences physical and other relevant to the above example of Swedes and Congolese may also be ascribed at least in part due to the (up to 6%) Neanderthal genetic contribution to modern European genomes.

Possibly, though many of those differences emerged well after Neandertals and other cousins disappeared. EG Blonde hair(around 12,000 years ago), blue eyes and European pale skin(30-15,000 years ago) that we'd recognise today. So it seems unlikely we got them from Neandertals. Also Asians have a different suite of genes for pale skin. If the genetic locks are correct of course. I'm personally dubious about some of them myself and I think it's not the reliable tool it's often held up to be.

Now it is possible non African folks got some features from Neandertals(and Denisovans). They did get things like faster healing, quicker clotting and various immune system changes. Some Neandertals show genes for pale skin, light, even red hair. Some were darker. Their pigmentation seems to have varied over time and place, which is understandable*. They were around for hundreds of thousands of years and changed in their bones in that time, so not a shock to find they changed in other ways as local adaptations. After all as we see above many modern human physical changes appear to be quite "recent" and spread quickly. Their red hair mutation is different to the modern one however. I haven't read much definitive on the pale skin mutations. If they're the same or close to modern Europeans then they might be the source. Or it could be a similar adaptation to similar environmental stresses. In light skin's case, vitamin D production in higher latitudes.







*one thing I've mused on is that if you look at the pigments they collected and we assume they were often used as body art, then they tended to collect pigments that were dark in colour, blacks, dark reds and the like. Pale skin is a far better canvas for that palette. If you look at very dark peoples today who use body paint they instead choose whites and yellows and light reds. Makes sense.

"Species" has always been a vague definition anyway. Subspecies ditto. I would see all modern humans as one species, but with distinct populations within, with quite the bit of overlap for most, less overlap for others. IE those who are more isolated geographically or culturally. Pygmies would be one such of the latter populations. They became genetic isolates over time, with distinct genotypes and obviously phenotypes. Looking at their genetics though there is quite the bit of back and forth from outside populations. Ditto for the San Bushmen. Indeed the latter show genes that seem to have come from all populations European or west Asian about 10,000 years ago IIRC. This stuff can happen quite "quickly". EG the study into Irish Travellers that found distinct genetic markers with them when compared to the wider Irish population. Basically because over a few centuries they were more culturally isolated. We see similar with some European Jewish populations, where because culturally they tended to marry within the population and the faith some have distinct genetics and higher frequencies of some genetic mutations, both good and ill. Even there the bulk of European Jewish genes are European in origin rather than Middle Eastern, so they certainly "married out" enough for that to occur.

That's been a consistent thing with modern humans. As well has having kids with other humans we met on our travels we also traveled backwards and had kids with people from the areas we came from. It wasn't all one way, or as simplistic as out of Africa is seen in the popular mind. "We" came from a group that appear to have been around in the general area of Ethiopia. However that same bunch also went south and west within Africa and other Africans went east and north. It's all extremely fuzzy. And that's before the migrations that started but went nowhere, but who left some genetics going on in the areas they abandoned.

Another aspect is genetic isolation. Neandertals and Denisovans were separated from their African roots and each other for hundreds of thousands of years, with very different environmental stresses and were rare in the landscape as apex predators will be and had less overlap and migrations, so were quite "inbred" at times. This led to distinctive genes and physical features, which themselves varied over time. The "classic" Neandertal runs from about 150,000 to 80,000 years ago. Before that they were more robust, after more gracile. They were following kinda the same trajectory as moderns in this. This makes them more of a "subspecies" of each other. One that could reproduce with each other, because of close common ancestry, but more different than peoples today. Indeed some researchers reckon that Neandertal/Modern pairings could have kids, but their fertility was compromised. Fine the first generation, but second and third could have problems. IIRC because they found a very strong selection against Neandertal reproductive genes or something like that.

I'd not heard of any fertility problems between San folks and their neighbours(or the various Pygmy populations). Then again how many from outside are getting together with locals? I would suspect in areas of overlap they surely must be? I have read down the years of Europeans(nearly all men) having kids with Papuan/Amazonian/various African tribes/Tibetan/Australian Aboriginal women with no problems and Europeans should be more genetically isolated than local populations. I'd be surprised to find fertility problems TBH. The vast bulk of our shared genetic legacies are at most within the last 50-80,000 years, not the 200,000 years compared to Neandertals et al. Personally I'd bet the farm those to do with fertility are within pretty much the same ages and the same worldwide.

As for distinct physical features. This has long been a thing in humans, even within the same population. Europeans are about the best example of this in modern terms. They have the widest range of skin tones, eye colour and hair colour and texture of any population on the planet. Even within the same family you can have a blonde and a redhead with blue eyes or brown. Go back much further and consider the Homo Erectus(who I would see as not human) they found in Georgia. This really threw researchers as the wide range of physical features in near every skull dug up, would if they had been found on their own in different areas might well have been labelled as different subspecies, even distinct species. They were that different, yet they all came from the same place and within a very close timeframe.

Well they've only a part of the skull O, so there's a bit of conjecture going on at this stage. The fragment is thicker than a moderns or Neandertals, but it could be a very robust individual, they could look like us, or Neandertals but just with thicker cranial bones. Until someone finds a more complete skull we won't know.

I would strongly suspect we already have more examples of them in museums and university collections. There are quite the number of Asian skulls that have been found from the time periods Denisovans lived. Given they seem to have crossed paths that resulted in having kids together with both Neandertals and modern humans at least three times I would be truly shocked if a few of the existing Asian archaic skulls weren't them.

In the link they note that the skull thickness is more like Homo Erectus which they didn't expect, yet the skull found in Henan China from around 100,000 years ago had researchers all a quiver because it seemed to share both Erectus and Sapiens features.


Then there's the much older Dali man skull which looks very archaic, but also has features that are similar to Sapiens at a time when no sapiens had any business being there.



And here's another lad found elsewhere in China, from around 100,000 years ago that shares features with both sapiens and neandertals.

Though personally I'm very dubious of such descriptions. Just because a species has what look like sapiens features, doesn't mean it has anything to do with our line of sapiens, or is indicative of sapiens in isolation.

In any case any one of them might be Denisovans hiding in plain sight.

While that's some interesting and impressive science on the gene expression front, IMHO it's yet another example of major conjectural leaps springing from meagre actual science that tends to infect the study of our ancestors.