Meet the Denisovans, the newest members of the human tree of life

Last March I wrote here about a 50,000-year-old pinky bone found in a Siberian cave that might belong to a previously unknown kind of human. Scientists had isolated mitochondrial DNA from the bone, which suggested that it belonged to a separate lineage that was neither Neanderthal nor human.

Well, the other shoe has dropped, and it turns out to be a big old boot.

In tomorrow’s New York Times, I report on a new paper in Nature in which the scientists describe the nuclear genome they have now extracted from the finger bone. Its owner looks to be a cousin to Neanderthals, belong ing to a lineage that split off from them about 400,000 years ago. The members of this lineage have been dubbed the Denisovans, after the name of the cave where the pinky bone was found, Denisova.

But wait! There’s more. First off, the scientists also got Denisovan DNA out of a tooth in the cave. It’s a tooth unlike human or Neanderthal teeth, the scientists claim.

And there’s more! Neanderthals interbred with the first humans to emerge out of Africa, it appears, judging from the presence of Neanderthal DNA in European and Asian genomes (but not African ones). Now it appears that Denisovan DNA is in the genomes of people from New Guinea, but no one else.

I know! New Guinea? Siberia? You can’t get there from here!

There is so much to this story that I’m going to have to blog some more about it in the near future. For now, check out the article. All I want to say for now is that a week in which I get to write about a cannibal Neanderthal family massacre and a new lineage of humans known only from a pinky and a tooth–whose genes survive today even if they themselves do not–is the kind of week that refuels my love for science.

At the time, scientists were reporting on the 15,000 base pairs in its mitochondrial DNA that they had sequenced

13 thoughts on “Meet the Denisovans, the newest members of the human tree of life

  1. So, how much more work needs to be done before there’s a paper naming and describing Homo denisovensis?

    Wasn’t the peopling of New Guinea a separate event from the peopling of, e.g., Australia or Indonesia? And in that case, isn’t it more likely that the ancestors of today’s New Guineans picked up the Denisovan genes en route?

  2. Wow! This was predicted in april and, I assume, now tested as an early Yule gift:

    “… microsatellite positions … Using projected rates of genetic mutation and data from the fossil record, the researchers suggest that the interbreeding happened about 60,000 years ago in the eastern Mediterranean [the Neanderthal ~ 5 % genetic material] and, more recently, about 45,000 years ago in eastern Asia [the Denisovan ~5% genetic material]. …

    The researchers suggest that the population from the first interbreeding went on to migrate to Europe, Asia and North America. Then the second interbreeding with an archaic population in eastern Asia further altered the genetic makeup of people in Oceania.

    Don’t you just love genetics!?

  3. A more likely answer to the genes being picked up in route is that the tooth and pinky weren’t originally from Siberia, but were moved there with other human movements. IIRC, the tooth and the pinky are pretty common fetish items for magical rituals, they may have been carried by someone or traded to make their way to that cave rather than directly off the original individual.

  4. Now, it’ll be interesting to learn the related function of genes and regulatory regions integrated within genetic material that have been preserved among the Melanesian population.
    I’d like to think that the Denisovan material would confer some sort of evolutionary advantage rather than being only the result of pure chance and isolation.

  5. After reading this and articles about the “Oh yes she did /Oh no she didn’t” claims of interbreeding between Granny and the Neanderthals, a question occurred to me – what does convergent evolution look like from a genetic/genomic perspective?
    Obviously if two such disparate species as say, hermit crabs and bats had developed similar traits to solve similar environmental challenges, we wouldn’t conclude they were hooking up on the beach after midnight. But in the case of more or less closely related species such as hominins, where the the potential for genetic mutations is constrained by a substantially common genome to start with, the extant trajectory of evolutionary trends due to previous mutations, and a not terribly dissimilar environment providing the not terribly dissimilar survival challenges, how do we know that the specific instances of DNA that show up in apparently different lineages is due to inbreeding rather than to convergent genomic evolution?

    [CZ: It’s practically impossible that 2.5% of a genome would evolve into nearly identical sequences in two separate lineages. That’s over eight million base pairs.]

  6. Absolutely incredible as the treasure troves of ancient humanity are discovered we are beginning to witness just how diverse humanity was from the standpoint that our lineage literally was the last man standing ?

    Despite timing and fossil recording in the knowledge of the many different time zones that claims some absolutely different species of the same tree never met the other the fact remains that next week or next year we may be able to find that Denisovan or and Neanderthal and Homo Sapiens very well at one time could have been as diverse as the Ape ?

    If that highly unlikely theory were to become a reality than all interbreeding aside Homo Sapiens and our large brains very well could have decimated anything different yet the same for barbaric tribal ethnic paranoid resourceful reasons ?

    It would be like as if the Baboon grew larger brains and began to walk upright all the time then carried a club and decided to hunt down anything they perceived as different from themselves ,Hey look at ourselves and what the Europeans did to Aboriginal and other peoples simply because of self perceptions and paranoia of others who are same yet are somewhat different ?This story just has me on the edge of my desk ?Thankyou

  7. what is really fascinating is complete lack of any interbreeding evidence imprint on mtDNA and Y chromosome. If you look at mtDNA and Y it is clear out of Africa migration map, no more no less.

    Suppose the lack of Denisovan/Neanderthal mtDNA is easy to explain by involving “rape and pillage” scenario.. 2 hostile sides at war with one being wiped out in the end.

    However this should have left some Y-chromosome evidence, which is none.

    Perhaps hybridization could not produce any viable male offspring, the male offspring was not fertile, or perhaps was looking too much like enemy and got wiped out in infant age due to social taboos?

    Fascinating detective story of our Granny must say!

  8. What i find amazing is walking through a crowd of thousands in NYC or any other international city and hear anyone say there is no evidence of interbreeding between hominids through the millinia.

    I know with the interbreeding we continue to practice between races (not a bad thing) white skin, red hair and blue eyes may be a thing of he past too but it doesn’t take millions of years to homogenize a gene pool.

    With dogs it takes 5 generations of selecting the right dogs and thats good enough to get papers for your very own new breed.

    i know i love to over simplify but no matter which way you go with gene therapy mixing them or splitting them … every now and then a blue eyed red headed Neanderthal is gonna pop out when you thought they were long gone

    ya gotta remember Mendel’s square it’s too easy to see just looking around all those pre-homo sapiens, all those green and yellow and smooth and wrinkly peas … still have their genes in our pool

  9. Since Neanderthals, Denisovans, and Sapiens were able to interbreed and their offspring able to reproduce, doesn’t that imply that our relationship within the genus Homo is intra-specific and not inter-specific?

  10. Carl, I also want to know, why they could not detect the Neanderthal genes in die mitochondria in the first place. Why only later in the nuclear dna?
    Does that mean that the mother line was Homo sapiens and what about the Y chromosome?
    How many breedings took place to end up with only 4%, can you tell us the factor?

    This proves that Homo is not ‘n pure specie and all the variations are only different types.

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