SIBERIAN SURPRISE: DNA retrieved from a fossil found in Denisova Cave, located in the Altai Mountains, belongs to a previously unknown form of human. The excavation field camp is visible in this view from above the cave.
Image: Johannes Krause
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For much of the past five million to seven million years over which humans have been evolving, multiple species of our forebears co-existed. But eventually the other lineages went extinct, leaving only our own, Homo sapiens, to rule Earth. Scientists long thought that by 40,000 years ago H. sapiens shared the planet with only one other human species, or hominin: the Neandertals. In recent years, however, evidence of a more happening hominin scene at that time has emerged. Indications that H. erectus might have persisted on the Indonesian island of Java until 25,000 years ago have surfaced. And then there's H. floresiensis—the mini human species commonly referred to as the hobbits—which lived on Flores, another island in the Indonesian archipelago, as recently as 17,000 years ago.
Now researchers writing in the journal Nature report that they have found a fifth kind of hominin that may have overlapped with these species. (Scientific American is part of Nature Publishing Group.) But unlike all the other known members of the human family, which investigators have described on the basis of the morphological characteristics of their bones, the new hominin has been identified solely on the basis of its DNA.
Johannes Krause and Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and their colleagues obtained the DNA from a fossilized pinky finger bone found at Denisova Cave in the Altai Mountains of southern Siberia. The species was impossible to determine from the shape and size of the bone—it simply did not contain any diagnostic morphological traits. But there were good reasons to believe it came from a Neandertal or an early modern human. For one, the bone was recovered from a stratigraphic layer of the cave dated to between 50,000 and 30,000 years ago that contained artifacts belonging to the so-called Middle Paleolithic and Upper Paleolithic industries associated with these two groups. For another, Neandertals and modern humans were the only hominins known to have lived in this region during that time period. But the DNA the team extracted from the Denisova pinky bone turned out to be markedly different from DNA sequences previously obtained from early modern humans and Neandertals.
The researchers focused on a type of DNA known as mitochondrial DNA (mtDNA). Mitochondria are the power plants of the cell, and they have their own DNA that is separate from that housed in the cell nucleus and is passed down from mother to offspring. Because each cell has thousands of mitochondria, but only a single nucleus, mitochondrial DNA is much more abundant than nuclear DNA and is therefore more likely than the latter to be preserved in fossilized bone. To date, scientists have sequenced the mitochondrial genomes of both Neandertal and early modern human individuals, and the sequences for the two groups are quite distinctive.
Comparing the order of the genetic "letters"—or base-pairs, as they are termed—making up the Denisova mtDNA with the sequences of modern day humans and an early modern human, Krause and his collaborators found that the Denisova mtDNA differed from humans today in nearly twice as many letter positions as Neandertal mtDNAs do. Further analysis indicated that the most recent common mtDNA ancestor of the Denisova individual, Neandertals and modern humans dates to around a million years ago (making it twice as old as the most recent common mtDNA ancestor of Neandertals and moderns). This divergence date, the team says, indicates that the Denisova mtDNA is distinct from that of the H. erectus population that left Africa 1.9 million years ago, and also from that of the Neandertal ancestor H. heidelbergensis, which branched off from the lineage leading to modern humans around 466,000 years ago. As such, the researchers contend the Denisova mtDNA reveals a previously unrecognized migration out of Africa by a hitherto unknown group of hominins. (The team is holding off on giving the creature a formal name for now, but informally they refer to it as X-woman.)
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28 Comments
Add CommentHere's a question I've never found the answer to. DNA is an unstable molecule. What's it's half-life? I find it hard to believe an inherently unstable molecule can persist for thirty thousand years.
Reply | Report Abuse | Link to thisDNA survives for millenia by being re-created every time a newborn comes along, through egg and sperm combining. This is really interesting, and it is the basis of being human beings, and of our human doings. Humans beings doing readings on being human is to be doing what only human beings can do!!
Reply | Report Abuse | Link to thisDNA survives for millenia by being re-created every time a newborn comes along, through egg and sperm combining. This is really interesting, and it is the basis of being human beings, and of our human doings. Humans beings doing readings on being human is to be doing what only human beings can do!!
Reply | Report Abuse | Link to thisI heard of a theory that Neanderthals didn’t die off, but were assimilated by Homoerectus (spell?). If that’s the case, what if Asians came from a mixture with Peking man? Could this “new species” be between Neanderthal and Peking man? With this theory, modern man should be called Homo Homogeneous, and If not now, then soon! (Although not in our lifetimes) With the way we move about the world and the stigmas of traditions are dropping. The future sees us as all the same (if our differences don’t kill ourselves first.)
Reply | Report Abuse | Link to thisSigh.
Reply | Report Abuse | Link to thisAlready with the name calling.
Don't you have anything useful to add to the conversation?
Ihitnails: In scientific circles, there are two hypotheses about the emergence of modern humans. One is called the "multi-regional" hypothesis and the other is called the "recent single-origin" hypothesis. You are referring to the former, but it’s the latter that is considered to be the broadly accepted model. You can do your own research on these. It’s not my place to say which is correct, but researchers say that the weakness of the "multi-regional" hypothesis is that there is no supporting DNA evidence for it. In other words, DNA research shows that all living people today have a recent common ancestor and that there is no contribution from any other human branch, including Neanderthals.
Reply | Report Abuse | Link to thisSo what you're saying is that if evolution by natural selection is how species come into being, then there would be only one species.
Reply | Report Abuse | Link to thisSurely you can see that the existence of one species will itself alter the environment, providing new possibilities for other survival strategies? For instance, if a creationist poos in the woods there will be all manner of species who are able to use the energy within the faecal matter. It is unlikely, although not impossible, that another creationist will choose to make use of it.
That is what an ecosystem is, and it is within such systems that evolution occurs. Life in these complex systems does not amount to a monolithic 'either/or' where only one species can win.
Surely you can see that.
So what you're saying is that if evolution by natural selection is how species come into being, then there would be only one species.
Reply | Report Abuse | Link to thisSurely you can see that the existence of one species will itself alter the environment, providing new possibilities for other survival strategies? For instance, if a creationist poos in the woods there will be all manner of species who are able to use the energy within the faecal matter. It is unlikely, although not impossible, that another creationist will choose to make use of it.
That is what an ecosystem is, and it is within such systems that evolution occurs. Life in these complex systems does not amount to a monolithic 'either/or' where only one species can win.
Surely you can see that.
Someone wrote, "I feel sure that there is an intelligent design to all species to keep that species unique and separate from other species...if there wasn't, then every living thing on this planet would look exactly alike."
Reply | Report Abuse | Link to thisHow, then, do you handle the live, directly observable interaction between certain snakes and snails of Southeast Asia? The snakes have developed mouths with handedness (more teeth on one side than the other), which are better able to eat some snails whose shells curve in a certain direction. The snail population has likewise shifted in response to this predation.
Research Masaki Hoso's team studied this extensively and released data in 2007. The team said that "The remarkable diversity of sinistral snails in Southeast Asia may be attributable to ‘right-handed predation’ by snakes."
http://www.livescience.com/animals/070308_right_snakes.html
mt DNA and Y chromosome DNA are somehow the two dead end in human genome. There seems to be a modern trend to study personal ancestry by analyzing haplogroups of these 2 DNAs, but the rest of genome between the two extremes of Y and mt DNA contains a lot of data on ancestry too. In studying ethnic background of cultures, there is an easier to read fact that gives also hints: food cooking recipes. Many of us are aware of some kind of chinese food, presented wrapped inside a pasta sheet. If you watch enough ethnology films, you'll realize that this kind of cooking is found with nearly no changes in Siberian tribes. As narrow eye openings, high cheeks ad short noses are an adaptation to avoid freezing of acral parts of body in extremely cold weather, the conclusion that chinese races have Siberian roots, as native americans have, is easy to make. Modern greek cuisine has lots of common recipes with turkish ones, not suprising when one considers that turkish invaders went several times back and forth of this land. There are people that say no people having strong genetical connection to the greeks that build Partenon currently remain, but up to 25% of the spaniard people of today have the so called greek foot, the second toe being longer than the first one, as in the classical greek sculptures. What happened to those guys? Surnames are also a clue to more recent ethnic background data, but here also, a lot of artificial changes took place for convenience reasons. How deep the Mormon registry on humankind family tree arrived?. There is a lot of funny science, enjoy it
Reply | Report Abuse | Link to thisI Love This Stuff!!
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I Love this Stuff!!
Reply | Report Abuse | Link to thishttp://billygambelaafroasiaticanthropology.wordpress.com/
ihitnails - I kinda like that story too, feeling some affinity with Neanderthals. Kinda like relating to T-Rex as a kid.
Reply | Report Abuse | Link to thisHowever, I also heard a story stating that there's more genetic diversity among tribal groups in East Africa than there is between Asians and Europeans, or any other 'race'.
These two stories seem to be mutually exclusive, since Neanderthal's genes seem to be quite different from modern humans, although one Neanderthal in the family tree might not be very noticeable by now. However, if there are few Neanderthal genes left in the pool it seems unlikely that they could be producing distinguishing characteristics among groups.
to frgough,
Reply | Report Abuse | Link to thisDNA is actually a very stable molecule which is why it is used to carry our genetic information. The half life of DNA in ice is 1.1 million years.
Very exciting. But when will scientists finally recognise the enormous evidence that exists for the Almasty/Bigfoot as a living hominoid? They need to get to grips with this and stop ridiculing the subject, as it is possible that this is what this new species discussed in this article is (as well as many of the other human-type fossils that so far defy categorisation) . There is far more evidence for the existence of the Almasty (a Eurasian name for the Bigfoot) than there is for many already recognised mammal species. Indeed there have been many sightings of the Almasty in the Altai mountains where this new hominoid fossil was found. Overall, the evidence for the existence of the Almasty/Bigfoot is: several bones, three confirmed DNA sample from Asia and Norther America (identified as 'unknown primates), thousands of documented sightings from across Eurasia and the US states, numerous enormous human-type faeces, many thousands of footprints, and a large body of knowledge of their behaviour from the small groups of Russian researchers who have been studying the creatures for the last four decades. At least, this new discovery is taking scientists closer to eventual recognition, as they are slowly realising that a greater vcariety of hominoids exists that they thought and that some of these were very, very recent. For information on the Russian research on the Almasty see: http://www.stgr-primates.de/
Reply | Report Abuse | Link to thisfrgough
Reply | Report Abuse | Link to thisUnlike a radioactive isotope, there is not a definitive "half-life" of DNA. Many factors influence it's degradation: temperature, light(UV/Sunlight),humidity etc...contribute to how efficient both endogenous and exogenous DNAses work(enzymes that chew up DNA). The best case scenario for prserving ancient DNA is very cold, very dry and very dark.
"enormous evidence that exists for the Almasty/Bigfoot as a living hominoid"
Reply | Report Abuse | Link to thisThis is a joke, right?
Re: enormous evidence for the Almasty/Bigfoot - no, its is not a joke. Thousands of sightings (by locals and researchers, including many full encounters), thousands of footprints, DNA samples, the creature is known by local tribes across a huge range of Siberia etc. etc. Drop the dismissive attitude and find out the information for yourself.
Reply | Report Abuse | Link to thisGBristol, anyone who knows a little bit about science knows that sightings are not evidence. That would make anyone who knows something about science doubt whether you know very much about science. Hence the (deserved) dismissive attitude.
Reply | Report Abuse | Link to thisPotatoChop - no need to be impolite. I know very well what science and evidence are (studied biology at Cambridge University, thank you). Sightings are not scientific evidence and I did not claim they were, but they are nevertheless a form of evidence (such as in court and for policy-making). But that is by the by. If you read what I wrote in full, you will see that I mentioned DNA samples, bones and faeces. The point I was making is that there is more scientific (plus much other) evidence for this creature than there is for other already recognised mammal species, and hence this subject deserves proper investigation by the scientific community (China is the only country which is officially researching the subject). This subject is so important but very hard to progress because people are closed minded (one of the last social taboos left over from religious thinking that we humans are unique, perhaps?). If you have any interest, please check out the subject for yourself.
Reply | Report Abuse | Link to thisGBristol, I did read what you wrote in full. You said, "Thousands of sightings" in direct response to what amounts to "enormous evidence". Now you’re backpedaling on the relevance of sightings. Why did you mention them at all? One wonders. They have no bearing whatsoever in scientific research.
Reply | Report Abuse | Link to thisIf the DNA has been identified as "unknown primate", then it isn’t evidence "for" big foot, is it?
Your stance is schismatic. On the one hand, you insist that scientists don’t take this view seriously, while on the other hand, you insist that the scientific research is on your side. Which is it? Are the scientists with you or against you?
Hi PotatoChop. Oh dear. Sightings are very relevant. Scientific research normally starts with observations (eg. observation of a falling apple suggested existence of gravity etc.). There would be no reason to research the Almasty/Bigfoot (or any topic), if there were no indications that it might exist. The DNA being identified as 'unknown primate' indicates there is a (scientifically) unidentified primate in the northern hemisphere (ie. 'unknown' in this context means scientifically unknown). Finally, there is a difference between scientific evidence and the scientific community. So far, all of the evidence has come from researchers who are not part of the established scientific community. I would like to see mainstream scientists engaging in this subject, producing their own evidence, publishing papers etc, and then the debate can be put on a more authoritative footing. Does that make sense?
Reply | Report Abuse | Link to thisGBristol: Your comparison of Bigfoot sightings to falling apples doesn’t work. The latter is reproducible and yields reliable observational data, while the former does not. The motion of objects (falling, orbiting etc.) can be studied and analyzed. Sightings amount to nothing more than hearsay. They produce no observational data. I think you can see the difference. The controlled observation of moving objects qualifies as evidence, while sightings of Bigfoot do not.
Reply | Report Abuse | Link to thisCall it "unidentified" or "unknown". Any way you slice it, you are NOT talking about evidence "for" Bigfoot. You can’t go to the scientific community saying that you have some DNA that hasn’t been identified and convince them to study Bigfoot. The non-scientists you mention should try to get a real scientist to establish where the DNA falls in the primate tree. No need to mention Bigfoot. Just do DNA comparisons to find out on which primate branch the DNA belongs. Then you would actually have something you could call evidence. Until then, you don’t have any.
i think you might be refering to my complaint that MORBIDITY , FECUNDITY and COMPETITION , if they were the only factors in evolution, then we would only have one eternally living agressive and exponetially proliferating canabilistic organism left. this theory doesnt explain adaptation, and the mutual.
Reply | Report Abuse | Link to thisi did not mean to imply creationism. but there is more at work, proportionately more than codon alterations, to answer for your snake and snail. and that is the synthesis the ecosystem makes of evolution.
So they may have all interbreed and we have a much bigger diversity than we think!!
Reply | Report Abuse | Link to thisit is not all human beings doing what human beings do but also human beings going where no human beings have been going before and doing it with the other human beings that are there being humans and doing what human beings do while going about what humans beings go about doing while being human beings doing it too.
Reply | Report Abuse | Link to thisand the eggs are always eagging the sperm on all the time but only the ones that wag their tails the most get close to making the most of it and getting egg on their face!
Reply | Report Abuse | Link to thisbuddhacosmos: Regarding morbidity, fecundity and competition, you said that "if they were the only factors in evolution, then we would only have one eternally living agressive [sic] and exponetially [sic] proliferating canabilistic [sic] organism left."
Reply | Report Abuse | Link to thisStill at it with the straw man, I see (as well as a plethora of inexplicable misspellings). You left out (among other things) cooperation. Never mind that a population can be very well-adapted to its environment only to be wiped out by a virus or by changing climate (which negates your ridiculous and utterly false claim). It is also true that symbiotic relationships abound (which should help you see why you have again presented a straw man argument). The core principle that you reject is that natural selection operates on genetic diversity, which stems essentially from mutation and viral injection (transgenesis). Then, of course, there’s recombination, which yields novel gene combinations - and then there are regulator genes, which turn genes on and off - and so on and so on. Modern evolutionary theory most certainly does explain adaptation. But the only way to see that would be to actually understand the principles, which, as you have repeatedly demonstrated, you don’t.
Instead, you propose the following stunningly vague hypothesis: "the synthesis the ecosystem makes of evolution." That doesn’t mean anything. If you think it does, please elaborate.