Ancient genomes 1: The Denisovans


[ Music ] When we think about what has
changed in the last 5 years of understanding human
evolution, there is no story that is bigger than the
story of the Denisovans. This is a population
that we know today only through their genomes,
and it’s a population that archaeologists had not
suspected they would find to exist. It’s a really crazy
story, and it’s one that so illustrates the
importance of ancient DNA and reshaping our view of
the dynamics and interactions of ancient humans in the past. We have, through ancient DNA
technology, recovered evidence of a population that
is among the ancestors of living humans today, and
that’s tremendously exciting, but it also shows us just
how much the fossil record and the archaeological
record leave out as we’re considering the
dynamics of ancient populations and how they came
to be modern humans. Denisova Cave is a cave in the
Altai Mountains of Siberia. It’s a region that is today
in the nation of Russia, and the Altai Mountains
are themselves a very interesting area. There’s archaeological evidence
of very early modern humans, of Neandertals and now
of this third population, the Denisovans. All of which were existing in what is a relatively small
area near the borders of Russia, Kazakhstan, Mongolia, China. It’s a tremendously
interesting area, an area that is really the
crossroads of Central Asia, and it’s an area that has
been investigated intensively by Russian archaeologists
for now, at Denisova Cave
more than 30 years. The Denisova excavation has
produced really interesting evidence of the behaviors
of ancient people, and until recently,
everyone assumed that these ancient people that were being documented
there were likely Neandertals. I will say that at Denisova
Cave itself, there are bones that do represent Neandertals, because we have ancient
DNA evidence from some of them that’s very similar
to Neandertal specimens that are found elsewhere in
Europe and in Central Asia. But the evidence from one of
these bones was very different from Neandertals and
even more different from most living people. That evidence came from
one bone which is the tip of a fifth finger, or a pinky,
and represents an older juvenile or a young adolescent female. We know it’s female from the
two X chromosomes in the genome. That bone produced better, more well-preserved
ancient DNA evidence than any other bone had
before this one was sequenced. Denisova is truly an
extraordinary situation, in terms of ancient
DNA preservation. The reason why is that the
Denisova Cave is a cold cave year-round. It’s a cave where the
average temperature around the year is
zero degrees Celsius. So, essentially freezing. That low temperature maintained
over tens of thousands of years has effectively
preserved DNA from multiple specimens. So the really, really interesting genome
came from a pinky bone. It’s something that as a
paleoanthropologist I have to say is shocking. This is the kind of bone that
if you’re really a specialist, you will know that there was a
pinky bone from Denisova Cave, but otherwise you’re not going
to pay a lot of attention to it. The pinky doesn’t tell us a lot about the behaviors
of ancient hominins. You can probably do your
dissertation on every pinky that was found anywhere
in the world, but it wouldn’t be a very
interesting dissertation. Osteologically, this
is not great evidence about this ancient group, but the genetics give us the 3
billion base pairs copied twice that existed in this
ancient person’s genome. They’re telling us
today far more about this ancient population than we could ever have
discovered from bones alone. So it’s hugely important. How do we know the Denisova
individual represents a different population? When we look at the sequence
of this genome compared to human sequences, compared
to Neandertal sequences, it is very different
from both of them. Now, across the genome
as a whole, it’s slightly more similar
to Neandertals than it is to living people around
the world and especially to living people in Africa now. So there is some
relationship between this genome and Neandertals, but that
genome is very slight compared to the relationships
among modern humans now, and it’s very slight compared to the relationships among
different Neandertal sequences that we have. So this genome appears
to represent a group that was quite distinct
from Neandertals and quite distinct
from recent humans. It was a different population. We know something about the
dynamics of that population. For one thing, this genome
shares some functional genes with Neandertals that
lived in Central Asia. Those functional genes are
genes related to immunity, and so there was interbreeding
between this population and the nearby Neandertal
populations, interbreeding that was sufficient to
spread at least some genes that had adaptive value. We also know from this
genome that it has parts that are very divergent
from Neandertals and from recent people. Most of the genome is sort
of somewhat divergent, but some parts of the
genome are very divergent, and that includes the
mitochondrial DNA. The mitochondrial DNA of the Denisova genome
is very different from Neandertal mitochondrial
DNA and very different from the DNA of living people. Living humans for their
mitochondrial DNA share an ancestor around 200,000
years ago. We share an ancestor with
Neandertal mitochondrial DNA around about 500 to
700,000 years ago. We share a common ancestor with the Denisova
mitochondrial DNA well more than a million years ago. Coupled with evidence
from other genes that also show this pattern,
the Denisova genome looks like it represents an
interaction with a population that was yet more different from
us than the Neandertals were. The Denisova genome may have
interbred with something like a Homo erectus population or a significantly divergent
archaic human population that we haven’t yet discovered. That is so interesting, because
it’s showing us the dynamics of populations that we can’t
witness with bones alone. We also know something
about the population in which the Denisova
genome existed. That population was smaller than
the population that gave rise to living people, because the
Denisova genome is more inbred than living people are. So Denisovans were a
pretty tight-knit group, a group that was relatively
small and persisted for a long time relatively quite
separate from other populations but with some interbreeding
with quite distant populations. The other thing that we
know about the dynamics of the Denisova population
is that they interbred with the ancestors of
some living humans. We know that because when we
compare the Denisova genome to the genomes of people living
today in aboriginal Australians, Highland New Guinea, to
some extent Melanesia — which includes New
Caledonia, New Britain and nearby islands — and in
the very easternmost parts of Indonesia and across
the Pacific in Polynesia, when we compare the
genomes of those people, we discover that they
have similarities with the Denisova
genome that no one else in the world today shares. So the Denisovans were partial
ancestors of the genetics of these populations that live
at the southeastern most extreme of the old world
human existence. That is super interesting
because what it tells us is that the Denisovan
population was extensive enough that the emerging
population of modern humans, carrying with them a very high
fraction of African ancestry, interacted with and interbred
with this Denisovan population, giving rise to the colonization
of Australia, of Melanesia, and of other points
in the Pacific, and that later there
was a movement of people that did not carry the Denisovan
signature of intermixture that spread across Asia
and covered up the evidence of this earlier mixture. Present-day Asians have
a very, very small degree of Denisovan admixture. In aboriginal Australians
and Highland New Guinea, we see 5% of the
genetic heritage of those people is a
population that was like the Denisova genome. On the mainland of Asia
it’s well under 1%. Maybe as low as .2%. So we’re looking at a
very complex dynamic in which human populations
emerged. They mixed. They separated to some degree. Further populations emerged and
mixed and colonized new areas. Later populations emerged
and spread and covered up the evidence of some
of the earlier mixture. Human populations in their
genetic history are what archaeologists would
call a palimpsest. A palimpsest is a
manuscript that was written on and then rubbed out
and written on again. In medieval times monks that were copying manuscripts
sometimes reused the same pages. Modern human genetic
ancestry is like that. Our ancestry comes from multiple
layers of ancient movements that emerged from Africa,
became somewhat differentiated from each other, mixed with
each other and then remixed as later people left Africa. It is a really complicated
and interesting scenario, and the Denisova genome
demonstrates it more than anything else. But the Denisova
genome is not alone. We’re increasingly learning, as
we’ll see later in the course, that when we look at ancient
DNA within regions of the world, we discover that the ancient
DNA comes from populations that no longer are strong
representatives of the ancestors of living people in
the same regions. Ancient Europeans that
lived before the time that agriculture spread into Europe represent
only a small fraction of the ancestry of
living Europeans. Ancient Indonesians that were
there as Australians originated from that area are no
longer representative of present-day Indonesians
that lived in the same area, and the Denisovans show
that that goes back into deeper time periods. So that modern humans are
coming from a complex process, where ancient variations
are being established and then remixing and then
partially being rubbed out by the movements of new
people that are expanding with some mixture and successive
layers of this process. The Denisova genome is telling
us about these ancient dynamics. They’re dynamics that go well
back into the Pleistocene and that involve archaic
humans that lived in Africa and that lived across Eurasia. It’s a tremendously
interesting discovery, and there are other
aspects to it that involve the
functions of these genes. I’ll talk about the importance
of gene functions and the way that we’re learning about the
biology of these ancient people when I talk about
Neandertal genetics, because in those cases we’re
able to discover something about the biology of an ancient
population beyond its bones. The Denisova genome is giving
rise to similar insights about a population
where the bones that we have are very, very few.

Comments 81

  • Thank you so much for sharing your knowledge of and passion for these groundbreaking discoveries. You are obviously a very accomplished researcher and educator, but also an excellent presenter. What a very exciting time to be alive; watching the unfolding of monumental truths that were unthinkable just a very short time ago. Excellent work!      

  • a miracle find…

  • and in America.. do we study the bones – NO.  we reburry them.  sad, really sad.  what new ancestors could we find if we took a different approach.

  • I was told that the ukrainian pyramids recently discovered in crimea may have been built by denisovans. Any comments on this?

  • wow welcome the Denisovans!!!
    http://www.collective-evolution.com/2015/03/01/new-ancient-mystery-human-species-identified-shakes-up-the-theory-of-evolution/

  • Thanks for the information, well done

  • According to the results of my DNA sample sent to the National Geographic genome project, I am 2.8 per cent Denisovan….and on my father's side.

  • just watched a Paavo vid- it said the dna was just as diverse as ours so they must of had a huge population.
    This video says the opposite.
    Funny how it seems all our theories are based on finds from caves or desert land. Some sqeak in because of accidental find.
    I think we need to just start digging on a grid around the entire earth.
    I would like to here more on windover bog, a bit newer but interesting. About 200 bodies recovered and around 9kyo WITH INTACT brain material. Weaving was also found- just these two alone should make this one of the Gems of archeology- Where is it?

  • This was very compelling… really liked the palimpsest 10:10 metaphor describing human evolution.

  • Well explained and Palimpsest metaphor great for explaining waves of migrations and mixtures. Could have done with some diagrams.

  • Very good talk, i enjoyd alot!

  • Accept it or not, this pattern of mixing between genetically distinguishable types of humans is happening to this day.

  • my mother comes from Fiji I was always told that they are related to the people of Australia

  • Thanks for what you do, Dr. Hawks.

  • I wonder if Denisovans DNA testing will become available at 23andme,like with the Neanderthal?

  • Like vote just for teaching me a new word today: palimpsest. ; )

  • I have great respect for John Hawks. He speaks plainly and doesn't muddle the research with leftist propaganda.

  • http://www.nature.com/news/hominin-dna-baffles-experts-1.14294
    I don't know if this has already been explored here.

  • So, what you are saying is that there were several distinct groups of people that interbred with other distinct groups. And that they COULD interbreed. That is pretty much what I always thought.

  • I slept with a Denisovan and a Neanderthal once when in a drunken stupor, at least thats what they looked like.

  • So well presented! Thank you !

  • Fascinating subject. I do hope we will see a more or less complete Denisovan Genome in the near future.

  • Question, I herd a hypothesis that the people that make Australian Aboriginals, native's of Papua New Guinea , and other people's of Oceania came form a sub-set of people that came out of Africa before the wave of people that would latter become Asian's, Europeans, and so on. If that is the case, I have my own idea that is just hypothesize. What may account for the different Denisovan percentage between Australian Aboriginals, native's of Papua New Guinea , and other people's of Oceania than that of the people of East Asia is that the Denisovan's died out between the two waves of modern Humans and the Denisovan percentage in East Asians were watered down by the second wave of humans that came from from Africa.

  • 6 Creationists watched this video.

  • Can't they use that genome to reconstruct what they looked like?

  • Superb explaination. Not only is this filled with information, it is put together in a way that almost anyone would be able to understand it. Einstein once said that if you can't explain. something simply it means you don't truly know it. Sounds like you really know your stuff. Keep up the good work.

  • Excellent talk.

  • The people of the Andaman Tribes, have they ever been touched by the Denisova-Genes like the tribes of New-Guinea and Melanesia have been?

  • The word Denisovans sound like humans descended from aliens concocted by conspiracy theorists. It's akin to those nonsensical words like lemuria and Atlantis.

  • Is it possible that the denisovans were surviving homo erectus?

  • Neanderthal's are not modern humans, only Africans.

  • DNA testing is a simple test,so stop with the the silly words

  • 1:47. what is the relivence of the united states here?

  • So the next step is to find a skeleton of one of these . Interesting. Where to look?

  • Thank you so much for such an amazing speech! Greetings from Brazil!

  • Help me understand. It is said that we share 98.8% of the same DNA as a Chimpanzee but only 1-4% with Neanderthal and Denisovans. I am sure people are using different formulas to explain  our relationship with these relatives because it is obvious that we are much closer related to Neanderthal and Denisovans than a chimpanzee. So my question is: What is the actual percentage total that we share with these relatives? Correct me if I am wrong but I am sure that we share more than 4% of our DNA with a tomato but I am not going to mate with one and then have tomato DNA in the human Genome.

  • I read an article recently – although I am unsure of its authenticity- which suggests that there was an earlier migration of Homo Sapiens, around 170,000 years ago, who interbred with early Neandertals. It suggested that later Neandertals shared mitochondrial DNA with later Homo Sapiens as a consequence.

  • Out of Africa theory has been debunked. Europeans have no common ancestry with Africans.

  • Also ancient americans are no longer present day representatives of american pop

  • Those mixtures of bastards wont give you blond hair, blue eyes and good looks, you know. And on the other hand, we have not all had primitive ancesters, like the ugly arabs who flew airplanes into World Trade Center.

  • According to my results of the DNA sample sent to the National Geographic genome project, I am 3.4 per cent Denisovan. And 44% Northern European.

  • Wow! I hope you make more videos as you are so good at explaining things going from micro to macro and how it effects modern humans today. A lot to lecture about yet done so well. I was watching another video about Denisovans that was so muddled and making way out claims of 10,000 rpm tools used to make a piece of jewelry found in a Denisovan cave. I wonder why only one tiny bone and 2 teeth have been found in 30 years so far. If anyone knows, please post something. I suppose if they buried their dead it would have been in a different cave or not in a cave at all, or perhaps they didn't believe in rituals around death too. I wonder with the genome now so well preserved if it gives information as to what they looked like in profile and average height and facial features etc.

  • thank you John Hawks. at least now i know the technical name for the way my brain works. palimpsest. lets just call it the 'memory like a dry-erase board gene'.

  • If only one individual , how did you tell they were more tightly related? I left out the word inbred.

  • My theory is that denisovan is simply a Neanderthal/Erectus mix (possibly even pure erectus)… when you look at the genetics data with a dielectical mindset, all makes more sensr leaving out all preconceived opinions

  • Okay I think I may stupidly have forgotten something in between all of this. Did Denisovans come from Africa too in the very beginning or had they evolved from completely different place and had no relation with African ancient genomes ?

  • As a teacher I find it extremely difficult to concentrate on what he's saying standing in front of that blackboard. It's a mess!

  • Ok, so my thought is think of the different varying species of I don't know what, that was interbreeding to even get to early humans.
    I mean evolution in its early stages was two similar or multiple similar species breeding and creating a new species.
    This interbreeding has been going on since the dawn of life and the end result is every living thing on earth today.
    I believe we are all a combination of every living thing on earth.

  • OMG thank you for your hard work. You're a bad ass academic.

  • This channel is exceptionally informative

  • Dennis or Denise – ovans ?

  • So who is the denisovan and how do they know and also could this all be a fabrication of bullshit.

  • What did the denisovans build architecturally, because their jewelry was the cutting edge?

  • You give an excellent presentation. You speak clearly and don't stumble over things like some do. Thanks

  • Sir, I've been writing a story of 'my' 1st Humans – near the Aral Sea… who later mix with other passing Homo. – Help me?

  • I wonder if Denisovan DNA gives Asians their particular look.

  • Dwarves & Giants & Hobbits were real …other hominin races we warred with, co-existed with, interbred with.

  • Coincidences stand what you understand and brand real.

  • I'm enjoying learning about Ancient genomes and appreciate your work. You're informative and easy to listen to and understand. I've subbed and am following on Facebook.

  • One of the most impressive videos i've seen on the subject of evolution. This is the first time i've ever written a public comment, which is a measure of just how impressed i am. As a retired lecturer, i consider that i can recognise true professionalism when i see it. One thought – would a map have been useful when talking about pop. movements? Or would that have taken away too much focus from what was being said?

  • Was this long ago to have been related to Pangia….Perhaps it is simple : Maybe the land masses were much closer to one another then they are now ?

  • Thank you for this amazing explanation.

  • why is it that every model of migration I see for denisovans, Neanderthals & modern humans is always based on a map of the African, European, Asian and middle eastern map of today and always seems to be static all the way back to 800,00 years or so (Denisovan migration ((assumptively, based on mitochondrial dna split)) to the present. it doesn't seem likely to me that this would be the case.

  • Very interesting but please keep the pictures in view longer and do not flash them on as it's difficult to focus on them.

  • Awesome video thanks!

  • Nice presentation. Thank you.
    I guess I am an enthusiast for paleoanthropology…Since I have followed the Denisovan DNA since its discovery…And Kennewick Man…And the Star Cave/Homo Naledi in Africa where they had to get tiny women to get to the bones…All of it. Anyway, thanks.

  • I just googled this because my boyfriend has this dna

  • I have the denisova gene 30ky also have Altai 5oky ? Can anyone tell me what this means ?

  • I like ur sweater

  • Dr. John Hawks. Univ of Wisconsin (we are so fortunate) Madison.

  • why is that cave that cold? and why would our ancestors live there if it was?

  • My family group hails from the Denisovans cave area thank you. Can’t wait to do DNA test

  • rather interesting

  • John, you interrupted the music !! lol

  • Very interesting and informative, and, although it is evident that the presenter is a serious academic, he is capable of presenting extremely complex knowledge in an accesible and appealing way. Thank you for that.

  • Fascinating.

  • Very well explained, Dr Hawks. Thank-you. Is there anything to say that the Denisovans didn't migrate in the other direction? Could they not have originated in the Pacific somewhere? Seems to make more sense in many ways given the existing evidence.

  • and it continues to mix…. that's a crucial thing to understand from this studies!!

  • All hominds are an endless mix of interbreeding since the beginning of time.

  • Denisovans: The information in my little finger is more important than you homo sapiens have in your entire body!

    Homo Sapien: Yeah, so?

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