Just as with modern Homo sapiens, the genome of a single individual cannot tell us exactly what genes and traits are specific to all Denisovans. Yet, just one genome can reveal the genetic diversity of an entire population. Each of our genomes contains information about generations far beyond those of our parents and grandparents, said David Reich, a researcher at the Massachusetts Institute of Technology–Harvard University Broad Institute and a co-author on the paper. Scientists can compare and contrast the set of genes on each chromosome—passed down from each parent—and extrapolate this process back through the generations. "You contain a multitude of ancestors within you," Reich said, borrowing from Walt Whitman.
The new research reveals that the Denisovans had low genetic diversity—just 26 to 33 percent of the genetic diversity of contemporary European or Asian populations. And for the Denisovans, the population on the whole seems to have been very small for hundreds of thousands of years, with relatively little genetic diversity throughout their history.
Curiously, the researchers noted in their paper, the Denisovan population shows "a drastic decline in size at the time when the modern human population began to expand."
Why were modern humans so successful whereas Denisovans (and Neandertals) went extinct? Pääbo and his co-authors could not resist looking into the genetic factors that might be at work. Some of the key differences, they note, center around brain development and synaptic connectivity. "It makes sense that what pops up is connectivity in the brain," Pääbo noted. Neandertals had a similar brain size–to-body ratio as we do, so rather than cranial capacity, it might have been underlying neurological differences that could explain why we flourished while they died out, he said.
Hawks counters that it might be a little early to begin drawing conclusions about human brain evolution from genetic comparisons with archaic relatives. Decoding the genetic map of the brain and cognition from a genome is still a long way off, he notes—unraveling skin color is still difficult enough given our current technologies and knowledge.
New sequencing for old DNA
The Denisovan results rely on a new method of genetic analysis developed by paper co-author Matthias Meyer, also of M.P.I. The procedure allows the researchers to sequence the full genome by using single strands of genetic material rather than the typical double strands required. The technique, which they are calling a single-stranded library preparation, involves stripping the genetic material down to individual strands to copy and avoids a purification step, which can lose precious genetic material.
The finger bone—just one disklike phalanx—is so small that it does not contain enough usable carbon for dating, the researchers note. But by counting the number of genetic mutations in a genome and comparing them with other living relatives, such as modern humans and chimpanzees, given assumed rates of mutations since breaking with a last common ancestor, "for the first time you can try to estimate this number into a date and provide molecular dating of the fossil," Meyer said. With the new resolution, the researchers estimate the age of the bone to 74,000 to 82,000 years ago. But that is a wide window, and previous archaeological estimates for the bone are a bit younger, ranging from 30,000 to 50,000 years old. These genetic estimations are also still in limbo because of ongoing debate about the average rate of genetic mutations over time, which could skew the age. "Nevertheless," the researchers noted in their paper, "the results suggest that in the future it will be possible to determine dates of fossils based on genome sequences."
This new sequencing approach can be used for any DNA that is too fragmented to be read well through more traditional methods. Meyer noted that it could come in handy for analysis of both ancient DNA and contemporary forensic evidence, which also often contains only fragments of genetic material.
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Add CommentI have always thought that someday someone would come up with some kind of relationship between the Neanderthal and the true Aboriginal tribes of Australia. The two groups do share skull and skeletal similarities, a (mostly) short, powerful frame and musculature, and a very high level of intelligence---thought by some to exceed in intelligence the more "modern-man-like" varieties of humanoid, given the same point in time for comparison. That plus the fact that the Aborigines have lived in the same part of Australia for at LEAST 50,000 years. Could this be the connection, if there in fact exists one, between the two races? Am I all wet? Was there another shooter on the grassy knoll? Could Lassie really be 73-years-old?
Reply | Report Abuse | Link to thisVery interesting article. It always makes me a little uneasy when they say they "estimate the rate of mutation." Some recent research has shown that some mutations can happen relatively quickly, not in the steady, step-by-step process we used to know and love. Too many variables, I feel, to rely on for guessing age.
Reply | Report Abuse | Link to thisBut every step does take us closer and closer to new truths, and it is indeed an exciting journey.
Same here.
Reply | Report Abuse | Link to thisThis article has a link to a very thorough report:
http://www.nature.com/nature/journal/v468/n7327/full/nature09710.html
- which states:
"... our results indicate that Denisovans but not Neanderthals contributed genes to ancestors of present-day Melanesians"
For clarification I also read:
http://en.wikipedia.org/wiki/Melanesians
Если существуют разные измерения то возможно мир каждого измерения оставило свой след на Земле и некоторые следы могли пересекаться в поздней и начальной стадии эволюции.
Reply | Report Abuse | Link to thisThe translation (from Google Translate) is "If there are different dimensions of the world it is possible to measure each left its mark in the world, and some traces can interfere in the late and early stage of evolution."
Reply | Report Abuse | Link to thisIf genetical differences between MOdern European and Neanderthal is as big as between some Homo Sapiens groups, wouldn't be it proper to consider the neanderthal as part of the same specie as Homo Sapiens?
Reply | Report Abuse | Link to this@Tormento. Right, I was thinking the same thing. If one of the characteristics of a species is the ability to interbreed and produce viable offspring, as is the case with homo sapiens, Neanderthals, and Denisovans, we should all be classified as the same species (ie, homo sapien sapien, homo sapien denisovan, etc.) I can understand separating them in the beginning, but now that we know so much more that might need to change.
Reply | Report Abuse | Link to thisDoes the Denisovans' genome hold any clues about what they were like mentally and emotionally?
Reply | Report Abuse | Link to thisEmiliano, The Australian Aboriginals are not related to the Neanderthals any more than we are. Apart of some facial features, there are no similarities in the skeleton, etc. The Australian Aboriginals are as much Homo Sapiens as the white Europeans or any other human tribe in the world today. However, it is a mystery where from and how they reached Australia.
Reply | Report Abuse | Link to thisThe high cheekbones and slanted eyes of the current Chinese and some native American populations can be explained as adaptations to extreme cold, flat noses are harder to freeze, the high cheeks allow for space for bigger sinuses to heat incoming air, and the slanted eyes would protect them for freezing, the evident origin for this may be in a long stage of their ancestors in the Siberian climate, but this will raise another question: what prevented these people for thousands of years from going South, and from colonizing the warmer zones they inhabit today? Were they deterred by animals, let us say the "Ugra" or others, or by other human groups? The question is sound or silly?
Reply | Report Abuse | Link to thisAccording to my references in comment #3, the Australian Aboriginals may be less related to Neanderthals than the rest of the non-African population and more related to the Denisovans than all other non-Melanesian groups. In casual comparison, Australian Aboriginals generally seem to have broader features and a more robust skeletal frame than most orientals, for example, similar to my very Irish frame. IMO there is no value judgement to be drawn from that casual observation except that Australian Aboriginals might generally be better shot-putters than runners, as am I...
Reply | Report Abuse | Link to thisBTW, it seems to me that the development of language and art in modern humans seem to come after extended contact with Neanderthals. One could even speculate that it was the increased requirement for improved communications if not interbreeding with Neanderthals that originally produced these developments in modern humans.
We cannot ignore the fact the modern human population exhibits a highly diversified set of characteristics.
Some anthropologists indeed classify Neandertals and Denisovans as subspecies of humanity. At the news conference, a reporter asked Dr. Paabo this very question. He answered, "The Denisovans were a different group of humans. I wouldn’t call Neandertals a different species. I stay away from that debate." It is our semantics, or drive to classify live. I look at a chihuahua and a Great Dane and wonder how they can be the same species.
Reply | Report Abuse | Link to thisThe researchers are edging toward the reality of ancient sex drives. If there wasn't a successful breeding, it was because it couldn't, not because they looked and thought no.
Reply | Report Abuse | Link to this"More problematic is the reality that the human genome is still a vast catalogue of the unknown and scarcely known. The Human Genome Project’s most startling finding was that human genes, as currently defined, make up less than 2 percent of all the DNA on the genome, and that the total number of genes is relatively small. Scientists had predicted there might be 80,000 to 140,000 human genes, but the current tally is fewer than 25,000 — as one scientific paper put it, somewhere between that of a chicken and a grape. The remaining 98 percent of our DNA, once dismissed as “junk DNA,” is now taken more seriously. Researchers have focused on introns, in the gaps between the coding segments of genes, which may play a crucial role in regulating gene expression, by switching them on and off in response to environmental stimuli...
Reply | Report Abuse | Link to this... some 90 percent of the protein-encoding cells in our body are microbes ... 99 percent of the functional genes in the body are microbial ... exchanging messages with genes inside human cells ... microbes cohabitating our body outnumber human cells by a factor of 10, making us actually “superorganisms” that use our own genetic repertoire as well as those of our microbial symbionts ... We just happen to look human because our human cells are much larger than bacterial cells ... no matter how you look at it, it’s high time we acknowledge that part of being human is being microbial ... Microbes may indeed be subtly changing our brain early on — and for what purposes we cannot yet say ... the mere fact that microorganisms can shape our minds brings up many more questions about how humans develop their identity ... these findings call for a complete re-examination of human physiology and immunology. Attributes that were assumed to be human traits have been shown to result from human–microbe interactions."
So why not use the other 98% of the genome to trace history?
http://blogdredd.blogspot.com/2012/04/one-mans-junk-gene-is-another-mans.html
I take note of Xopher's unease over rates of mutation because I share them.
Reply | Report Abuse | Link to thisNonetheless, let us consider an early out of Africa event which mixed with Denisovans on its journey along the southern margin of Asia to Melanesia and Australia.
Then came the 'Toba eruption event' and its postulated
'genetic bottleneck effect at 70,000 ybp. The first runners are safe but isolated in SE Asia and Oceania while their tail across south Asia has died off due to the Toba ashfall
When the Toba effect has abated, there is a new out of Africa to repopulate Asia.
(Meanwhile, what became of the Denisovans?)
Wow! So much to discover, to learn. Please, someone sequence the 'hobbit' genome.
Cheers
TKerr
Damn! Forgot to check the email me box. If you have a reply, please respond to this.
Reply | Report Abuse | Link to thisTKerr
I was disappointed to learn recently that the Toba genetic bottleneck hypothesis has met with some recent criticism. Please see
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/Toba_supervolcano#Evidence_against_a_population_bottleneck
I'm now wondering how the 'hobbits' could have survived the nearby Toba eruption - I guess they stayed in their little caves...
I think you'll be notified - I always check but oftentimes don't receive any notification...
I'm still ready to lay money that in the near future a direct correlation will be found between the Australian Aboriginals and the Euro Neanderthals, whether by lineage by interbreeding with the newly-found Denisovan, and tied to the projected penchant for travel being suggested of this new grouping, or by a forced, self-preserving exodus of the Neanderthal, in the manner of today's Arcadian now living in Louisiana (I only use this example to demonstrate the human drive to survive, notwithstanding any inference as to scope or size of said exodus, or of length of time frame). The Australian Aboriginals are as succinct a group as the African bushman or the pigmy, each being recognized by differences in frame, physical attribute, brain size, and pure appearance, but all unquestionably human. Once the European outcasts sent to Australia from Europe on prison ships "changed their ways" and quit running over the Aborigines like a Ford over a chicken, it dawned on these interlopers that the indigenous people were a tractible(sic), self-sufficient, highly intelligent, peace-loving subrace of people (can you say Neanderthal?). But if you can't look at the general physical makeup of an Aborigine and see the Neanderthal influence, then you ain't lookin', Bub.
Reply | Report Abuse | Link to thisIt would be difficult to prove when they interbred the last time.
Reply | Report Abuse | Link to thisAre we jumping the gun? There may be ninety percent similarity between the DNA of two species, but they are not important. The rest three percent are important. Cross breeding is very much a probability, but we should be careful before generalizing it.
Reply | Report Abuse | Link to thisbasudeba
Did Neanderthals and Denisovans interbreed?
Reply | Report Abuse | Link to thisDid Neanderthals and Denisovans interbreed?
Reply | Report Abuse | Link to thisDear God, that grates: "how small of a sample" (in the caption). I understand scientists not grasping the intricacies of usage, but journalists?
Reply | Report Abuse | Link to thisEmigration requires either surplus population or unlivable conditions in the current habitat. If they were surviving reasonably well in the north for a long period, but not so well as to produce excess population, there'd be no reason to migrate south.
Reply | Report Abuse | Link to thisConvergent evolution could also account for it. Flying squirrels, Colugos and Sugar Gliders look alike, but Flying Squirrels and Colugos share only a superorder, and Sugar Gliders couldn't be much more distantly related to the other two and still be a mammal.
Plamen its no mystery about where Homo Sapiens is from or how they reached Australia. We are from Africa - few would challenge that now. The genetic trail is pretty clear and the likely route is from the horn of Africa round the (now submerged) coastline of the glacial period. Homo sapiens is know for its exploitation of littoral resources so a coastline route makes a lot of sense for speed of migration and reasonably consistent habitat.
Reply | Report Abuse | Link to thisThe Autralian aboriginal form is likely to be the closest we have today to the way we looked at that time.
Emiliano
Reply | Report Abuse | Link to this"I'm still ready to lay money that in the near future a direct correlation will be found between the Australian Aboriginals and the Euro Neanderthals,"
A fool and his smoney are soon parted.
"But if you can't look at the general physical makeup of an Aborigine and see the Neanderthal influence, then you ain't lookin', Bub. "
So your basis for this assertion is what - they have the same number of limbs?
Taking a good look at Australian native people and then reconstuctions of Neaderthals, they have little in common; different skulls, different body shape, different femur profile, teeth, eyes and the list goes on.
Basically we have long escaped the 19th century and most of us have stopped making theories based on fanciful prejudice.
Xopher425
Reply | Report Abuse | Link to this"If one of the characteristics of a species is the ability to interbreed and produce viable offspring, as is the case with homo sapiens, Neanderthals, and Denisovans, we should all be classified as the same species "
Be careful not to fall into the trap of the species problem. There is no absolute definition of a species because the term species is simply a human attempt to classify things, even where nature doesn't accept the rules.
Although there is a low level of genetic mixing between the different types of hominid, this doesn't change the picture, it just blurs the edges.
It is pretty clear from the differing degree of their adaptations, that modern humans and neaderthals and other groups, are/have been seperate groups, and sufficiently so to warrant being different species.
My paper (un-published book) entitled: APACHE WAR DANCE shows in Chapter 4: "Asian Martial Arts are Part of Apache Tradition," that both Caucasians (the Ainu) and Asians (Dene-Yeniseian and Na-Dene = Athabascans) originated in North America and migrated back to Asia. I use linguistic evidence to show that Athabascans are directly related to the Japanese, Chinese, and Koreans.
Reply | Report Abuse | Link to thisMr. Hawks maintains: "Yet contemporary residents of mainland Asia do not seem to posses Denisovian traces in their DNA, a "very curious" fact, Hawks says. "We're looking at a very interesting population scenario"—one that does not jibe entirely with what we thought we knew about how waves modern human populations migrated into and through Asia and out to Oceania's islands. This new genetic evidence might indicate that perhaps an early wave of humans moved through Asia, mixed with Denisovans and then relocated to the islands—to be replaced in Asia by later waves of human migrants from Africa. "It's not totally obvious that that works really well with what we know about the diversity of Asians and Australians," Hawks says. But further genetic analysis and study should help to clarify these early migrations."
I suggest that Deni-sovans in Asia were not replaced by a migration from Africa, but rather, from North America. Both the linguistic and now, the genetic evidence seems to support this an "Out of America" origin for the Asians.
Please go to my FaceBook page: http://www.facebook/haashkee.dahszii
to see Chapter 4 and the rest or send me a message on FaceBook so that I can send you a free copy of the whole paper as an e-mail attachment. FaceBook crunches up the pages of my book.
The URL is
Reply | Report Abuse | Link to thishttp://www.facebook.com/haashkee.dahszii
I left off the .com