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DNA Analysis Suggests Humans Interbred With Denisovans

Posted by Unknown on from the star-trek-romance dept.

ananyo writes "Tens of thousands of years ago modern humans crossed paths with the group of hominins known as the Neandertals. Researchers now think they also met another, less-known group called the Denisovans. The only trace that we have found, however, is a single finger bone and two teeth, but those fragments have been enough to cradle wisps of Denisovan DNA across thousands of years inside a Siberian cave. Now a team of scientists has been able to reconstruct their entire genome from these meager fragments. The analysis supports the idea that Neandertals and Denisovans were more closely related to one another than either was to modern humans and also suggests new ways that early humans may have spread across the globe." wombatmobile linked to an article that focuses on the new techniques used to sequence the DNA of the bone fragments in question.

24 of 157 comments (clear)

  1. Considering... by camperdave · · Score: 5, Funny

    Considering what I've seen on the net, it doesn't surprise me in the least that H.Sapiens has interbred with anything and everything. The only surprising element would be whether or not there were offspring.

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    1. Re:Considering... by Monkey-Man2000 · · Score: 4, Interesting

      This probably won't be popular because it's not especially PC, but it's starting to actually appear that the 3 classical types of human as defined by 19th century Racial Science are becoming more scientifically delineated. Or at least things are breaking down broadly in similar ways. After-all, at some point there was a gross separation between Asians, Africans, Europeans, and the rest (that are usually a mix of 1+ of the others).
      One of the authors of this study or the others I read was talking about how he believed for a long time that Neandarthals are a sub-species of homo sapiens, while from this un-mixed homo sapiens are more closely related to the original and modern-day Africans, and then this Denisovans are related to more eastern groups including Pacific Islanders, Aboriginal Australian, and (maybe) what was classically related to Mongoloids?
      Still homo sapiens from a breeding standpoint but noticeably distinct even if it's 0.1-0.5% of the DNA. Doesn't mean anyone is better than others but we're phenotypically different if only in body morphology.

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    2. Re:Considering... by MightyMartian · · Score: 2

      Genetically there are something like 5 or 6 six races. Five races of sub-Saharan Africans, and then a sixth race everyone else. We know enough about the genetic makeup of various populations to put to rest pretty much all of Victorian racial theory.

      The problem here is concentrating on what usually amount to relatively insignificant morphological features of modern H. sapiens. Many features like skin color, shape of the eyes, slight deviations in skull shape, and so on are really very recent changes in modern humans. The fact remains that sub-Saharan Africa holds the highest degree of genetic diversity, and that almost all other populations throughout the rest of the world are far less genetically diverse, and it is this fact that has rendered the morphology obsessions of the Victorians. Not that different non-African populations don't have their unique morphological and heritable differences, but they really are very minor.

      If Neandertals and Denisovans did interbreed with humans (and there always seems to be a back-and-forth on this), they didn't leave much in the way of a genetic heritage in modern humans.

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    3. Re:Considering... by MightyMartian · · Score: 3, Insightful

      First of all you have to provide a scientific definition of "race". What the Victorians had was anything but a scientific definition. They had no genetic data, no real knowledge of the migration patterns out of Africa. Hell, most of the Victorian racial theorists assumed that humans arose in Eurasia, and that Africa was some sort of dead-beat dead-end where the lower races ended up.

      So, get to it. Give us a genetically meaningful definition of "race". I think you will find what most geneticists who have studied the issue have found, that if there are races; or more preferably sub-types of H. sapiens sapiens, they really do not line up very well at all with the morphological divisions that the Europeans set up. We have a much clearer picture now of how things went down when modern humans pushed out of sub-Saharan Africa. Still holes, but enough to tell us that simplistic notions like "negroid", "caucasian" and "mongoloid" do not give anything close to a reasonable picture of genetic patterns.

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      The world's burning. Moped Jesus spotted on I50. Details at 11.
    4. Re:Considering... by chichilalescu · · Score: 2, Insightful

      you do realize that there are communities in Africa where you can take two random people, check how much their DNA differs, and you will find that that difference is "bigger" than the differences between most "Europeans" and "Asians", right?
      the color of people's skin is related to the amount of sun their ancestors had to deal with. I'm not sure how long back in time, but probably a lot. the length of people's limbs and the thickness of their body has to do with the amount of heat their ancestors had to dissipate. that's about it.

      what this means in practice is that if you take blueeyed whiteskinned northern people, and you put them on a tropical island, and you check again in N generations (I'm not sure how large N is, but it shouldn't be very large), then you will find black eyed people with darker skin, only because it's easier to live there with these properties. in fact, I don't think it would be very easy to convince blue eyed whiteskinned northern people to go live on a tropical island...

      back to the issue of DNA differences: unless you have training in the area, don't try to draw conclusions, because these are complicated issues. for instance I read somewhere that when all you have to work with are bones, then you can say that two specimens are different species; but when you look at the DNA, you might say that they are indeed the same species. for instance pygmies are homo sapiens.

      my advice to you is to either get a degree in the field, or stop believing what people said 100 years ago, when it was still acceptable to be a racist in many circles (thus the biased conclusions you've been reading).

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    5. Re:Considering... by Anonymous Coward · · Score: 2, Interesting

      Provide us with a scientific definition of "language". Or else we'll have to give up on simplistic notions like English, German and French as well.

    6. Re:Considering... by Michael+Woodhams · · Score: 2

      The world of human genetics, according to Svante Pääbo*:
      A first wave of humans left Africa on the order of half a million years ago. These lead to the Neandertals and probably the Denisovans. (But perhaps the Denisovans were a separate migration.)
      On the order of 100,000 years ago, modern humans left Africa. On the way, they did a little interbreeding with Neandertals, so that all modern non-Africans are about 4% Neandertal by descent.
      A subpopulation of these interbred with the Denisovans, and this subpopulation ended up in Melanesia, but somehow left no genetic trace between there and Siberia where the Denisovan finger was found.

      I see very little similarity between this and the 19th century 'racial science'. If you insist on dividing people up into categories, this research has three categories, as do *some* of the 19th century schemes, and one of those categories is African. That really is as far as the resemblance goes.

      * Errors are mine, not Prof Pääbo's. Dates are from other sources and from my memory.

      --
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    7. Re:Considering... by Monkey-Man2000 · · Score: 2

      Exactly, and why in one of my posts the big Max Planck guy (Svante Pääbo in this article) that has been doing a lot of this DNA analysis thinks they are all sub-species of homo sapiens. In one article I read, he basically said he doesn't want to get into the debate about what a species is because it gets complicated. They interbred though he thinks from what I've read and he did one of the big Neanderthal studies and this Denisovans one and compared them to modern humans so I think he has a better idea than most people.

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    8. Re:Considering... by quenda · · Score: 5, Insightful

      First of all you have to provide a scientific definition of "race".

      There are similar problems trying to define species, genus etc. DNA and other new data shows that the tree of life is more complex than we realised.
      But a lack of a single simple definiton does not mean that species or race are invalid or unuseful categories.

    9. Re:Considering... by HiThere · · Score: 5, Interesting

      That's not actually unlikely. And the same reasoning would show why Neanderthal mitochondria don't show up in modern humans.

      In particular, it appears (or has appeared to a few anthropoligists several years ago) that Neanderthal women had a smaller birth canal that Cro-Magnon women, so if a normal Cro-Magnon infant were to attempt to be born to a Neanderthal woman, there would likely be a brith problem fatal to both the mother and the child. Going the other way around, however, should work. Neanderthal heads were slimmer than Cro-Magnon heads. And since mitochondria are only inherited along the maternal line, that would explain the absence of Neanderthal mitochondria in modern humans.

      This may not be quite what you meant, but it's the way I think it happened.

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      I think we've pushed this "anyone can grow up to be president" thing too far.
    10. Re:Considering... by HiThere · · Score: 2

      Species is fairly simple:
      Two animal varieties are of the same species if, given a chance, they interbreed and produce fertile offspring.

      Now this causes problems when you adopt a simple model, and then encounter ring species, like herring gulls. But it works fine for local populations. Just don't expect a global definition and it's ok.

      Genus is a totally artificial construct created by people to make their theories simpler to describe. It doesn't have any natural validity, any more than green or blue does. Where do you draw the line, and what do you call turquoise? It may be an artificial grouping, but it's a useful one. You build a Genus out of species that can be traced back to a common ancestral species. That defines the grouping mechanism. And within the constraints of that grouping mechanism, you draw the genus boundaries wherever it suits you.

      And yes indeed, the tree of life is much more complex. Viruses, e.g., can transfer genes between kingdoms, not just species. There are animals that have acquired plant genes. But this never happens to such an extent as to blur even species boundaries, much less genus boundaries.

      Race, however, does not seem to be a useful category, unless you are primarily interested in hair styles or melanin. The other, less observable characteristics (e.g. blood type) do not appear to follow the same boundaries. I was, I'll admit, afraid to marry a black woman in my younger days, because I was afraid she would carry sickle cell anemia. That does seem to be a genuine association (though far from certain). But many Semites also carry that disease. Esp. the ones from North Africa. Because it's a useful survival trait in areas where malaria is endemic. So it's following an environmental boundary rather than a "racial" one.

      --

      I think we've pushed this "anyone can grow up to be president" thing too far.
    11. Re:Considering... by neonsignal · · Score: 2

      Language boundaries are defined by mutual intelligibility of the communication system. This can be simplistic, but it provides a good first approximation that is testable. There are border cases (such as language chains), but on the whole it is a useful definition.

      In comparison, dialect contours are defined in terms of specific language features. What speakers call a "dialect" is an identification, and while this may correspond roughly to collections of language features, it is really a sociolinguistic definition of language variety.

      The notion of race is analogous to these sociolinguistic definitions, not to language; it is not defined by external factors, but by social ideas. There may be superficial features that are assumed to be associated with particular "races" (much as superficial language features are assumed to be associated with particular dialects), but these features are a poor definition of "race", because they are not clustered, and cross the boundaries of what people perceive as "race". In other words, "race" is a social construct.

      It is the notion of species that is analogous to language. Species boundaries are defined by fertile offspring. Again, there are border cases, but it is testable.

  2. Denisovans Extinct? by Jeremiah+Cornelius · · Score: 3, Funny

    I beg to differ. The Denisovan's were our next-door neighbors, when I was in grade-school.

    --
    "Flyin' in just a sweet place,
    Never been known to fail..."
    1. Re:Denisovans Extinct? by okcdan · · Score: 4, Funny

      Kind of dating yourself there Jeremiah. I do applaud older folks who embrace technology like the interwebs though, congrats!

      --
      D.
    2. Re:Denisovans Extinct? by Jeremiah+Cornelius · · Score: 3, Funny

      Carbon dating myself....

      --
      "Flyin' in just a sweet place,
      Never been known to fail..."
    3. Re:Denisovans Extinct? by jamstar7 · · Score: 3, Funny

      Carbon dating myself....

      Nope. Just dating yourself ;)

      Strange, he didn't mention he's from Arkansas...

      --
      Understanding the scope of the problem is the first step on the path to true panic.
  3. Listen... by Anonymous Coward · · Score: 2, Informative

    Humans have tried to interbreed with just about every species imaginable. Sheep, for instance. And, when drunk, even animals which sometimes predate upon humans. So I have no doubt that modern humans have interbred with Denisovan babes. We are some seriously horny, depraved bastards.

  4. Re:Clone possibility? by ColdWetDog · · Score: 2

    IIRC, the team managed to get 91% of the genome down 'pretty accurately'. That is a technological tour-de-force in and of itself but likely not enough to 'clone' somebody. Unless, perhaps, you added additional 'spacer' DNA - like from a frog.

    "I'm French, how do you think I got this outrageous accent?"
    "What are you doing in England then?"
    "Mind your own business."

    Na, would never work.

    --
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  5. Alyson Hannigan by tdelaney · · Score: 3, Funny

    Alyson Hannigan is modern-day proof of homo sapiens interbreeding with Denisovans.

  6. Re:And this is news how, exactly? by fm6 · · Score: 2

    It seems to me that Kirk's babes were all as human as he was. Like a lot of TV shows and movies from the 50s and 60s, TOS often assumed that other planets would be inhabited by people. TOS sometimes portrayed aliens as having weird physical features (as TNG and its sequels always did), but mostly the "aliens" looked like they came from Southern California — as indeed they did.

    I recently re-watched the original Planet of the Apes. When I first saw it 40 years ago, the teenage me was not bothered by the scientific silliness. But this time, I thought it was dumb that Taylor find a world inhabited by ordinary-looking mute humans and English-speaking apes, but it never occurs to him until the final scene that he's on Earth.

  7. Re:A total of five by fm6 · · Score: 2

    It's funny how only two species of recent hominids are commonly known

    Not funny at all. The first Neanderthals were dug up in 1829, and have had plenty of time to become a feature of popular culture. Except for the unavoidable Modern Humans, every other hominid is a very recent discovery. The Red Deer Cave people were only discovered in 1979. Hobbits and Denisovans were only discovered in the last decade,

  8. Re:And this is news how, exactly? by WastedMeat · · Score: 3, Insightful

    It makes much more sense, and is perfectly compatible with the rest of the plot, if you replace his period of muteness with a delay to learn the language. I have a suspicion this is what was originally intended but they did not want subtitles on the whole film.

  9. Denisovans are not exinct by Taco+Cowboy · · Score: 4, Informative

    Many Melanesians, Indonesians, Malays, Polynesians, Filipinos, as well as indigenous tribe on island of Taiwan, have Denisovan genes in them

    In fact, this isn't news anymore

    Back in 2010 there have been reports of similar findings. Here's one report from the BBC -

    http://www.bbc.co.uk/news/science-environment-12059564

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  10. Regarding the Neanderthal genes by Taco+Cowboy · · Score: 2

    The way I look at it - not scientifically based - just my own observation:

    While the Denisovan genes are in the bloodline of the islandic people of mainly West side of the Pacific Ocean, the Neanderthal genes are in the European and Asian bloodline - although percentage wise the Europeans have more than the Asians

    It seems to be that the Africans south of the Sahara Desert who are have the most "pure" Homo Sapien Sapien bloodline

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