Basically: Everyone outside of Africa has some Neanderthal DNA. It looks like the ancestors of the Melanesians interbred once with Neanderthals; the ancestors of Europeans interbred twice; the ancestors of Asians interbred three times.
Small amounts of Neanderthal DNA also show up in Africa, probably due to back-migration of people from Eurasia.
Denisovan DNA shows up mainly in Melanesians, but I think there is also a very small amount that shows up in south east Asia, some (or something similar) in Tibetans, and possibly a small amount in the Brazilian rainforest.
Now some kind of other archaic DNA has been detected in the Hazda, Sandawe, and Pygmies of Africa.
Since “Do Native Americans have Neanderthal DNA?” (or something similar) is the most popular search that leads people to my blog, I have begun to suspect that a clarification is in order.
Native Americans (Indians) are not Neanderthals. They are not half or quarter or otherwise significantly Neanderthal. If they were, they would have very noticeable fertility problems in mixed-race relationships.
They may have slightly higher than average Neanderthal admixture than other groups, but that is extremely speculative I don’t know of any scientists who have said so. We’re talking here about quite small amounts, like 0.5%, most of which appears to code for things like immune response and possibly some adaptations for handling long, cold winters. None of this appears to code for physical traits like skull shape, which have been under different selective pressures over the past 40,000 years.
As much as I would love to discover a group with significant Neanderthal DNA, that’s just not something we’ve found in anyone alive today.
This is really tentative! And I am not a geneticist, so at this point, I’m just crossing my fingers and hoping I didn’t read any graphs backwards.
Notes:
This map shows Neanderthal DNA admixture in modern human groups (solid color) and Denisovan DNA (polka dots.) The Denisovan estimates are less exact than the Neanderthal estimates. (Also, the guys with Denisovan DNA also have Neanderthal DNA; I just don’t know how much.)
The biggest problem I ran up against was a total lack of numbers. Seriously, everyone likes quoting that “1-4% of non-African DNA is Neanderthal” stat, but no one likes breaking it down by individual country or group.
Some of the sources contradict each other–first we have papers claiming that Europeans have more Neanderthal DNA than Asians, then papers claiming that Asians have more. I went with the Asians have more estimates, since they were more recent. Also, we now think that many African groups also have some Neanderthal DNA, due to more recent back-migration of Eurasians into Africa.
Most of this map is still completely blank, even though I’m sure the data is out there somewhere. I would really appreciate if any of my readers can point me toward a good old list of Neanderthal (or Denisovan) DNA %s by country or group.
Alternatively, if you’ve had your DNA analyzed and know your Neanderthal and/or Denisovan %s, feel free to share in the comments.
Worldwide distribution of B006, (from Yotova et al. “An X-Linked Haplotype of Neandertal Origin Is Present Among All Non-African Populations,” Mol. Biol. Evol. 28 (7), 2011).SNP PCA from Skoglund & Jakobsson’s “Archaic Human Ancestry in East Asia” (2011)
(Please note that Africans do not have chimpanzee admixture, despite the labeling on the graph–no human group has chimp admixture, because chimps and humans have different #s of chromosomes, so even if you could get a successful cross, the resulting child would be infertile, like a mule. I assume the point of the chimp node is just to represent that which has neither Neanderthal nor Denisovan admixture, though of course there is the possibility of some other form of archaic hominin admixture in Africans.)
So, Native Americans appear to have a ton of Neanderthal DNA. (Relatively speaking.)
Possibilities:
It’s all measurement error/convergent evolution/something else other than archaic admixture.
As much as I hate to say it, I still consider this very likely. There is just a ton of stuff that we don’t about the Americas–like how and when people first got here. I’m sticking here with what I think are the most scientifically-supported theories, but a lot of this is still quite disputed. In particular, all of this genetic admixture business is still kind of speculative, and when people start talking about finding admixture in the admixture, either life is totally awesome, or we’re trying too hard.
2. Survival at the Fringes theory
A lot of people seem to look at this data and respond with something like, “But Neanderthals are from Europe, not America!” But this is not a big issue; the Indians are descended from people who passed through Neanderthal-inhabited regions (the Middle East), just like everyone else with Neanderthal DNA. The migration to the Americas took place long after they acquired Neanderthal admixture.
But this doesn’t explain why they have so much of it.
My “concentration on the edge” theory states that when one population is displaced by another population, you end up with a “fringe” of the original population’s traits. Sometimes this fringe results in isolated groups, as the invading population completely surrounds or cuts off a remnant population from their former range.
The Ainu, for example, resemble certain other Oceanin groups, but not their neighbors, the Japanese. I’m speculating here, so don’t take my word for it.
But I have a much better case with the distribution of red hair:
(So far I have found nothing explaining that dot over in Russia.)
Red hair is highly associated with the so-called Celtic fringe. It looks like it’s highly concentrated in Wales, Scotland, and parts of Ireland, but since I know a little history, and I know these aren’t areas of concentration, but just the areas that managed to escape being displaced by Anglo-Saxon invaders, just by virtue of being further away from the south-east coast of Britain.
One can imagine that the isolated dot in the middle of Russia might, at one time, have been connected with the other red-haired regions before other peoples invaded the lands between them and cut them off.
Compare to the map of blond hair:
Blond hair looks like it has been spreading steadily outward from a central source.
So what does this have to do with Neanderthal admixture in Native Americans?
It means that I think the Native Americans may have closer to original levels of Neanderthal admixture, while people in Europe and Asia have lower admixture because they mixed with later waves of people who came from Africa and had no Neanderthal admixture.
3. The Bering Strait selected for Neanderthal admixture
4. Western diseases selected for Western immune responses
One of the interesting things about the Neanderthal DNA hanging around in people is that it appears to code for certain immune responses. West Hunter recently had a great post (TLRs, PAMPs, and Alley Oop) detailing how they work, but for our purposes, “provide immunity” is sufficient. Austin Whittall suggests that back when smallpox, influenza, measles, and all of the other Western diseases tore through the Native Americans, killing about 90% of them, the guys who had more Neanderthal DNA were more likely to survive because they were more likely to be immune to the same stuff as Europeans. By contrast, those Indians with less Neanderthal DNA may have had less immunity to the European diseases, and so been more likely to die, leaving behind a population of high-Neanderthal DNA people.
A couple of papers in Science and Nature recently proposed that Melanesian-related people somehow made it to the rain forest long after the other Indians got to the area. West Hunter helpfully summarizes them.
West Hunter suggests that the Melanesian-related people with their high-Denisovan DNA got to the Americas first, and were then replaced throughout the continents by later invaders, the ancestors of current Indians. The one place the Melanesian-related people managed to survive was in the depths of the rainforest, a very difficult place to conquer. Even today, there are “uncontacted tribes” living in the Amazon rainforest; if anywhere were a good spot for a group of humans to avoid getting conquered, the depths of the rainforest is a good one.
7. The low-Neanderthal and low-Denisovan area along the Baja gulf in Mexico.
So what’s up with that? As far as I know, the only people who don’t have any Neanderthal or Denisovan are Africans. (And even there, there’s a little, just due to back-migration from the rest of the world.)
Are these people descended from a totally different group that came directly from Africa?
There’s a tiny ethnic group in the area, called the Seri:
Dona Ramona of the Seri Indians of Sonora, Mexico
According to the Wikipedia, the Seri speak a language isolate–that is, their language, like Basque, doesn’t appear to be related to any other language on Earth–and they are not culturally connected with any of their neighbors. They’ve also held out significantly against Spanish and Mexican assimilation. In other words, they might very well be a totally isolated population that is not related at all to any of their neighbors.
The two different “real” maps how different things because they come from different scientists who came up with different data, but the overall picture is similar–if you look closely, both maps show a hotspot in Israel, for example. The second map looks less detailed, (hence their miss of several Middle Eastern hotspots,) but has a wider global range, which is obviously useful for our purposes. They also help show the importance of not putting too much stock in any single study about the distribution of a particular gene or allele or whathaveyou; different scientists come up with different numbers.
At any rate, while this could be just a totally random coincidence, if it isn’t, it’s awfully interesting, isn’t it? I know the Egyptians circumnavigated Africa; the Carthaginians and Phoenicians were also noted sea-farers. Or perhaps some other group I know nothing about from the region, before folks started keeping good records. Who knows?
8. Other people’s theories: Neanderthals, Denisovans, and H erectus made it to America before we did, and H Sapiens intermixed with them after they arrived; humans evolved in American, and then migrated to the rest of the world from there.
Overall: Recommended if you like Neanderthals or human ancestry. Probably not useful if you are already an expert in the field.
Pros: interesting discussion of flint-knapping, gluey pitch production, and Neanderthal burials.
Flint knapping is one of my occasional interests. It is surprisingly difficult to just pick up a rock and produce a useful tool. Without a good teacher, you quickly degenerate to banging the rock on the ground as hard as you can like a retarded monkey. If Kanzi the bonobo saw me trying to make stone tools, he’d probably bring me some fruit out of pity. “Poor hairless idiot ape,” Kanzi would think. “Can’t even make tools. If I don’t feed it, it’ll starve.”
Amusing digression time: Once I was walking through the city, in a semi-developed/semi-overgrown lot, and saw a bit of shiny rocks lying around on the ground. Unusual for the area, because the local geographic history hasn’t led to a lot of rocks on the surface, and most of those are of the duller sedimentary sorts (or, obviously, landscaping materials.) So I picked up this bit of flint, then another bit of flint, and then a larger one with obvious convex areas from being struck with another piece. And a few feet away, here was a piece that fit comfortably into my hand, perfect for knocking chips off the other chunk. Some of the pieces I even managed to fit back together, reassembling the rock that once was.
I came back with a small box and picked up all the bits of flint before development began on the lot. One piece does look like an arrowhead, but given that I found it alongside a bunch of chips that are more or less flint-knapping trash, the arrowhead’s creator probably thought there was something wrong with it.
Sure, the whole little box may be filled with little more than ancient trash, there is something I love about picking up these rocks and being able to see in their shapes the actions of some other humans, the angle they held that rock at, the way they smacked it with another rock to produce these flakes. To feel this connection between myself and some other human who walked here before me, and the traces of their life that no one else walking through that place had noticed.
Anyway, turns out the Neanderthals had a pretty interesting/unique way of making flint tools, that involved first shaping a large block of flint into a specific shape by flaking bits off the sides, and then, with one good hit, knocking off one large slice. This is a more complicated process than merely picking up a rock and whacking bits off of it it until you get an edge.
The gluey pitch seems to have been derived (distilled?) from birch bark. Some scientists demonstrated the process by burning a roll of birch bark in a pit, but they obviously did not use enough bark, and only got a smudge of goo. It’s a bit frustrating watching someone do something obviously wrong–since you’re filming this for TV, why not use a great big bunch of birch bark so you can get enough pitch to actually show us?
Anyway, looks like Neanderthals distilled this gluey stuff and then used it to help secure the flint tips to their spears, before thrusting them into the sides of enormous shaggy elephants, which are quite formidable animals. So the pitch (and bindings) had to be pretty darn good.
Neanderthals also seem to have buried their dead, though the show notes that their potential grave-goods pale in comparison to similar human burials.
The parts about Neanderthal DNA will be of interest to you if you don’t know about the Neanderthal/human DNA admixture business already, or you’ve heard about it but are still a little unclear on the details. The scientists interviewed claimed that it looks like there were a lot of interbreeding incidents rather than just a few, but “a lot” in this case does not necessarily mean “thousands”.
Cons: For a program that goes into depth on how inaccurate depictions of Neanderthals happened (ages ago, someone found a skeleton with arthritis and concluded that all Neanderthals were stooped,) their depiction of the homo Sapiens who first encountered the Neanderthals was also inaccurate.
The first encounters between humans and Neanderthals probably happened in the Middle East, shortly after h Sapiens left Africa, but before they had split into Asian and European branches. In other words, not to put too fine a point on it, whites did not yet exist. We’re not sure exactly when white skin evolved, but it probably wasn’t before h Sapiens got to Europe.
(Of course, it could be the other way around, and it’s the Bushmen who’ve changed since they split off.)
Either way, it’s pretty easy to assume things that are probably wrong, and the h Sapiens who first encountered h Neanderthals were probably more similar in appearance to modern Africans or Middle Easterners than Europeans.
A second issue occurred during a dramatization of the Neanderthal and h Sapiens DNA. Neanderthal DNA was depicted as red, and h Sapiens as blue. (Erm, I think. Unless I’ve got it backwards.) They then showed a “combined” DNA strand with blue and red pieces.
While this is a fine way to visualize what’s going on, I would just like to clarify that DNA isn’t actually blue or red, nor are there folks running around with mosaic red/blue variants.
You may be laughing (I burst out laughing at the sight of it,) but I know people who would very sincerely and devoutly insist that “Humans have different colored DNA from Neanderthals. I saw this program on PBS all about it, and I know PBS is accurate. You should watch the program!”
You can imagine how talking to these people makes me feel.
Finally, my last complaint is that there was no discussion of Neanderthal DNA in Native Americans!
Worldwide distribution of B006, (from Yotova et al. “An X-Linked Haplotype of Neandertal Origin Is Present Among All Non-African Populations,” Mol. Biol. Evol. 28 (7), 2011).SNP PCA from Skoglund & Jakobsson’s “Archaic Human Ancestry in East Asia” (2011)
Right, so what’s up with Native Americans? You may have noticed that during the discussion with the map, no jellybeans were placed on the Americas at all. What a pity, when there’s still so much about the peopling of the Americas that we don’t know.
In the future, I’m hoping for similar documentaries about the Denisovans and their DNA admixture in modern humans.
So why do we still have bits of Neanderthal DNA hanging around after so many years? Of course it could just be random junk, but it’s more fun to think that it might be useful.
And the obvious useful thing for it to do is climate adaptation, since Neanderthals had been living in dark, cold, ice-age Europe for much longer than the newly-arrived h. Sapiens, and so might have had some adaptations to help deal with it.
Okay, so here is something related I was reading the other day, that I consider pretty interesting. So it looks like the people who live up on the Tibetan Plateau (like the Tibetans,) are really well-adapted to the altitude. No mean feat, considering that other populations who live at similar altitudes don’t seem to be as well-adjusted, despite living up there for similar lengths of time.
Well, now it appears that the Tibetans have actually been living in Tibet for waaaay longer than expected, because the original h. Sapiens who moved into Tibet intermarried with archaic hominids who had already lived there for hundreds of thousands of years, and so probably picked up their altitude adaptations from those guys.
BTW, “species” is a social construct and you probably shouldn’t bother with it here.
So what kind of useful stuff might we have picked up from Neanderthals?
First I’d like to interject that I still find declarations of “aha, we got this gene from Neanderthals and it does this!” to be speculative and prone to changing. All of the articles I’ve read tend to report the same list of stuff in a similar fashion, so I suspect they’re all workign off one or two sources, which makes everything doubly sketchy. So we’re going in here with a big “if” this is true…
Some of the results are fairly boring, like Neanderthal DNA affecting hair and skin. We already speculate that skin tone helps us deal with sunlight levels, so that’s sensible.
More interesting is the claim that Neanderthal DNA may predispose people to Type-2 Diabetes and depression.
Now why the hell would it do that? It’s probably not *just* random–after all, large stretches of DNA have little to no Neanderthal admixture at all, suggesting that genes in those spots just weren’t useful, so why would we have retained such apparently negative traits?
Maybe, like sickle cell anemia, these things actually have a positive function–at least in the right environments.
I read a fascinating theory a few years ago that Type 2 Diabetes and Seasonal Affective Disorder are actually just part of our bodies’ natural mechanisms for dealing with winter. Basically, you’re supposed to eat plants and get fat all summer long, while plants are available, and then by winter, your ability to absorb more glucose shuts down (there’s no point since the plants are all dead) and you switch over to burning ketones instead and eating an all-mammoth diet.
(Some groups, like the Inuit and Masai, historically [and may today still] survived on diets that included virtually no plants and so ran all of their cellular energy needs through the ketogenic instead of the glucose system.)
During this winter time, humans, like other animals, slowed down and semi-hibernated to save energy and because why the fuck not, it’s dark and no one has invented lightbulbs, yet.
By spring, you’ve lost a lot of weight, the plants come back, and so does your ability to use glucose.
This theory is laid out in the book Lights Out by T. S. Wiley, if you’re curious. I thought it was a really interesting book, but you might just think it’s all crank, I dunno.
Anyway, a big hole in Wiley’s plot is how we actually got this adaptation in the first place, since it’s a pretty complicated one and h. Sapiens hasn’t actually been living in places with winter for all that long. Wiley just claims that it’s a deep internal mechanism that animals have, which always struck me as kinda bunk because why would a species that evolved in Africa, from other animals in Africa, etc., probably going back for million upon millions of years, have some sort of complicated system like this still functional in its genome? A trait that is not undergoing positive selective pressure is probably going to become non-functional pretty quickly. But the theory was cool enough otherwise to ignore this bit, so I’ve kept it around.
Right, so here’s the (potential) answer: h. Sapiens didn’t have this adaptation hiding deep inside of them, Neanderthals had it. Neanderthals had been living in cold places for way, way longer than h. Sapiens, and by inter-breeding with them, we got to take advantage of a bunch of cold-weather adaptations they’d developed over that time frame–thus getting a jump-start on evolving to cope with the weather.
At any rate, if Wiley is correct, and SAD and Type-2 Diabetes are actually part of a dealing with winter complex that benefited our cold-weather ancestors, then that wold explain why these genes would have persisted over the years instead of being bred out.
An easy way to test this would be to compare rates of Type-2 Diabetes and SAD among African immigrants to Europe/other wintery latitudes, African Americans (who have a small amount of Euro admixture,) and Europeans. (Watching out, of course, for Vit D issues.) If the Euros have more SAD and Type-2 Diabetes than Africans living at the same latitude, then those would appear to be adaptations to the latitude. If the Africans have more, then my theory fails.
So I still haven’t tracked down anything I consider a good source on the percent of Neanderthal DNA in people from particular regions of Europe, and I should note that at this point, I consider pretty much *everything* in the field of Neanderthal DNA in modern homo Sapiens quite speculative and not nearly has solid as people make it ought to be. But it’s still really interesting stuff, so here goes. I’ll start with a little background information in case you haven’t been following along:
1. Modern people tend to have a little bit of archaic DNA from non-human hominins. Pretty much everyone outside of Africa (including African Americans and even some Africans) has Neanderthal DNA; folks down in Papua New Guinea also have Denisovan DNA (I can’t remember if people outside of PNG have Denisovan.) People in Africa, I hear, have their own admixture from whoever else was living down in Africa. Oh, and people in Tibet have admixture from the hominins who used to live in Tibet before them.
2. Interestingly, the Neanderthal DNA does not appear to be concentrated where you’d think it would be. Sure, Neanderthals themselves hung out primarily in Europe and the Middle East, but American Indians seem to have the most Neanderthal DNA, followed by East Asians. (I consider these findings especially speculative.)
I have noticed in studying maps of different waves of human migrations that where one wave follows another, the first wave ends up way out in the fringes. Take, for example, the parts of Europe where people speak Celtic languages. Celtic languages were once widespread in Europe, covering France, Spain, Britain, Ireland, Switzerland, and a few other places, like possibly a town in Turkey. Today, Celtic languages are spoken in isolated pockets on the outer costs of Ireland, Scotland, and Wales. There are a few other isolated spots on the mainland coast where the languages persisted until fairly recently. Germanic peoples invaded all of these countries, taking them over and imposing their languages, until the Celtic languages are only left at the fringes, in places protected by their isolation.
So, likewise, perhaps Europe itself, being closer to Africa, had more invasions and so ended up with less Neanderthal DNA than the Americas, which were really bloody hard to invade.
There are a lot of other ways one group could get more Neanderthal DNA than another.
3. So how Neanderthal are you? On average, I believe non-African people have about 2.5% Neanderthal DNA.
For perspective, you have 32 great-great-great grandparents, who were probably born around 150 years ago, and 64 great-great-great-great grandparents, whom we’ll just neatly say were born around 170 years ago.
1/32 = 3.1%, so you’d expect to receive about 3.1% of your DNA from each of your 3xGreat Grandparents. 1/64 = 1.6%, so you get about 1.6% from each of your 4X Great Grandparents. So that’s where the average person’s Neanderthal contribution is–it’s like having one Neanderthal ancestor from the mid 1800s.
A lot of people claim to be ethnically Irish based on less.
4. I suspect Europe’s Neanderthal hotspot is Sardinia.
