all right well first of all I want to thank the organizers the Gibraltar National Museum for inviting me here it is always such a great pleasure for me to be here in Gibraltar not only because the incredible hospitality of the museum staff and of the and of the city but also because of the incredible engagement of the people of Gibraltar in these conferences in these meetings it is one of my favourite places to come because you have just incredible people who come out for meetings who are so interested and engaged in our science that we do but in our heritage and where we've come from and in my talk today I want to engage a bit with some of that heritage in a way that is new for me and I think we'll probably be new for for many of you I also want to welcome the people who are watching on YouTube if you're watching I think it's wonderful that we have live streaming of these meetings and I think it's great that we're able to reach out beyond beyond Gibraltar to the rest of the world I know that I have many many friends who watch these things and I just love that we can all come together and still be reaching out beyond the boundaries of the room I want to talk today about the ancestors of the Neanderthals I want to lead off by saying I do not know who the ancestors of the Neanderthals are and I don't think that any of us have a great idea of who the ancestors the Neanderthals are other than what I will tell you which is that Neanderthals had many ancestors we can point to a few of them but the formation of the Neanderthal population that deep time perspective on this population that we know so well from the fossil and archaeological records but we know relatively little about its earliest stages and the other populations that existed at the time they originated it right now is a very engaging mystery and I'm going to go into some of the reasons why this is today mysterious where the Neanderthals came from who their ancestors are I'm going to talk to some extent about the genetic record and I'm glad Svante is not in the room so that I can say whatever I want and and and I and I'm going to try to align what we're appreciating from the genetics with what we can see from the fossil record little as it may be in many cases and I'm going to point out what we don't know about the accuracy of genetic models and about the sort of accuracy of fossil observations that makes this a compelling problem right now so that's where I want to get to in this talk the end of the talk is we don't know so if you if you expect knowledge you can leave now all right so I want to begin by saying one point that's going to go throughout I put this on here to remind myself confusion about where the Neanderthals came from is in large part due to confusion about what Neanderthals are and this is an issue that's remained with us since the discovery of the Neanderthals and I'm gonna highlight some of that history but but I want you to sort of retain that confusion about where they come from is intrinsic to the fact that we're confused about what they are all right so first I want to talk about briefly we are learning incredible things about genetics right this last couple of weeks we have the news of of a an individual who has a Neanderthal parent and a denisa Vande parent right Neanderthal mother Denise amande father and this is a very special individual from Denis of a cave and the genetics tells us about this this now the paper doesn't use the word hybrid ever you do full-text search right there's no mention of the word hybrid the cover of nature says hybrid so clearly there's a mismatch of communication between what the geneticists and what the genetics is telling us and the way that this is being portrayed to the public right and that's something to note right when you have the cover of nature that says something different from the paper that the cover is representing it's telling you there's something mysterious about this I'm gonna try to highlight a bit of that you can you know ask other people who also know about the genetics about it but I want to focus to begin on one thing the discovery of these ancient populations from genetics has been transformative for our field we're finding populations by sequencing DNA from ancient fragments of bone we're finding populations that archaeologists and anthropologists had not guessed existed what does that mean because we guess that a lot of things right and and when we guess too much we get criticized you know people say that's x-files paleontology and this sort of thing right so it's it's making stuff up so there's a point to which you have to be very conservative and what you're willing to say I want to highlight a case where genetic knowledge leads to this sort of expanding cone of sort of ignorance all right so so let me just start with this is a map right this is from nature from a couple of years ago and you see here we've got the map that shows the geographic range of Neanderthals which is sort of blue the gray is modern humans who spread from Africa two hundred thousand years ago around the world by fifty thousand years ago and the hatched places of the places where they overlap and this pink glowing glob is Denis of a cave where you have this other population and Denis 'va becomes super interesting because a component of the genetics of the individual founder Denis of a cave is found in Australia and New Guinea so there's a contribution from this population to today's populations and yet it's not Neanderthal it says something else this encompasses a fairly accurate view of knowledge I would say in about 2011 2012 here's the range of Neanderthals here's Denis 'va now I want to point out the range of Neanderthals right where Neanderthals lived this is rather a nebulous concept where did Neanderthals live those of us who teach this stuff can answer the question right Neanderthals are the you know sort of middle and early Late Pleistocene population of Europe and we recognize that there's these other places that there were things that people call Neanderthals the Levant for instance Iraq for instance lose Becca stand for instance which is way over here the altai for instance when you find specimens that you attribute to this population it expands the range right it's what Milford said about the earliest a little bit ago yes always an earlier well when you find something outside the range it expands range there's always a bigger range now these ranges have a way of of mysteriously expanding and this is from new this is from New Scientist covering the same research that nature was covering with the other map right and here you've got the Neanderthals the including the Altai specimen which is from denisa behave they call it the Altai specimen because to retain confusion that is from the same place as the Denis of and Denis of a specimen in fact all of the Denis 'van specimens are from this one place and a Neanderthal specimen is from this place and the hybrid specimen is from this place it's a wonderful place right it's a very special place it's a great cave to visit I recommend it to everybody but you see that well the fact that we've got their genetics down here means that there must be some sort of denisa van range right they must have lived somewhere they didn't just live in this cave if they did they had to vacate it at the time the Neanderthals moved in so there was some kind of a you know trade-off and so they have to be somewhere and here they are right this is the north-south realm and the east-west realm okay now this is all popular science right so I'm not you know this but but I will say the popular science reflects a view of where the Denis Simmons lived that is held by professionals all right now we've got then the end result sort of denisa van frontier and here it's you know sort of at the pakistan-india border you know it looks like and and you've got these Neanderthals there in the range and then you've got these Denisovans in the rain well wait a minute the Denis have the only Denis of them that exists of course is up here so these these ought to be Denis Simmons right and you ask our colleagues and they will tell you I know that one of these is a Denis ofin we're going to find the DNA it could be right I'm not I'm not discounting the fact that we may discover that the DNA from a specimen from this area might share the same phylogeny that the Denis of an individual shares and so as a consequence you addicts but you can see well I will expand the range this one's better because you've got the Neanderthal range the Denis of them then the Anatole is are really pushing on the Denis events but the problem is that you've got this specimen from from Western China from sort of West southern China now that has Neanderthal traits and so as a consequence than the Anatol range has to push this way and the shrinks the denisa van range and then you've got erectus now erectus we have no positive evidence of erectus existing anywhere in the world after four hundred and fifty thousand years ago or so right we talk about them existing later as if this part of the world must be erectus realm and here's Denis 'van realm and here's a Neanderthal realm and notice right the fact is that all of these maps are built on a fundamental assumption about the way that hominin populations behave they behave like empires right now the president ears they push their boundaries they defend a range now this is this is not out of fiction right because when you look at the distribution of mammal species today and mammal subspecies you find that there is zones where populations come into contact where species come into contact there sometimes hybrid zones right there is a sense of geographical unity that exists within animal populations and we can expect that hominins had some sort of geographic unity right and in some sense they don't really behave like empires which as we all know the boundaries of the largest empire ever to existed in the world where one continued when one giant contiguous block which included Gibraltar correct no it was not a contiguously unless you count the seven seas right which makes it contiguous Britain rules of waves then I suppose it's all contiguous but it's not contiguous right humans do not behave as if their geographic ranges are contiguous even though when you look at humans as animals you'll see the populations tend to have some sort of geographic scope the fact is that when we find different populations in one place over a hundred thousand years or something as we've done in Denis 'va cave with something that looks in the end or tallish in its genetics and something that looks very different in its genetics we can expect that there were multiple populations that existed at different times that moved some large spaces and there were probably significant times when there was almost no occupation maybe total absence of humans and the fact is that humans are fluid in some sense across the landscape so I want to go to what the fossil evidence is so to start with what is genetics telling us I'm gonna come back to genetics in a second I want to first dive into history a little bit the fossil evidence of human evolution is spectacular right if we compare it to other kinds of creatures you know compared to the feathered dinosaurs we have tons and tons and tons of human ancestors and relatives represented in the fossil record but it is a very biased record it's a record that is biased in crania teeth and mandibles right this is a wonderful array at the Smithsonian Institution that shows you you can look at skulls from every time in place in human evolution but if you want to look at skeletons skip the Neanderthals and cro-magnon so except to say our understanding of Neanderthals comes from this time more or less right it comes from the time that we cared a lot about skulls and mandibles and teeth and a little bit less about the rest of the skeleton I'll tell you that when it comes to the rest of the skeleton and this is the figure that Milford showed you a little bit ago we have only a few specimens from the first 95% of the hominin fossil record that show you skull mandible teeth in association with post evidence right here they are some of them and you can see that they're scrappy there's not very many of them with Neanderthals we have a luxury which is incredible in our field that we have much of the skeleton represented in many individuals from some extraordinary sites right this is cropping ah here's your calf righto Chooch and you've got incredible array of skeletal evidence from crop 'inna right a hundred and twenty thousand years old more or less from cyma little soy sauce which i'll discuss later as an early member of the Neanderthal lineage you have the more fossil evidence than you have from any other site of hominids right you have an incredible array of evidence from this site you've got cool skeletons like this Homo floresiensis skeleton right from Liang Gua so we've got new discoveries that add skeletal evidence later in human fossil record we've got our site from from the rising star cave Homo Naledi material which is again a large array of fossils from around 250,000 years ago again we're looking at the last five percent more or less of our evolutionary history but we have a depth of evidence that we don't have in earlier time periods and yet nonetheless this is the Denyce of a finger bone that generated the genome that tells us there's a whole population right this is it and yet one tiny fragment can change the way we look at things and that's a humbling message right as a scientist because what you're saying is we've got all of this evidence that covers the last five percent of our evolutionary history we know a lot about this and yet I can find one finger bone and it could totally change things all right this really cool specimen from miss Leah cave that was published earlier this year that we have we have Mena in the room who's responsible for this it's a wonderful wonderful specimen that changes our view of the geographic distribution the dispersal of human populations right this aligned with early African populations in this Anatomy maybe this is the modern human outside of Africa etc etc all I'm saying is that even though we have a lot of evidence nonetheless we still act as if for good reasons the fragments shape the way we think and that's maybe humbling and and it maybe should make you sort of cautious well in the olden days of the 1950s they didn't have nearly as much evidence I'm not going to go back to the beginning of Neanderthals there are other people in Rome who can talk about the early history much more than better than I can and I'm not especially going to talk about what is this chart from F Clark Howell is responding to but I'll mention in the days when Clark Howell began writing about Neanderthals and their variation and to my mind some of the first modern thinking about where Neanderthals came from he was responding to an older idea that Neanderthals had existed in parallel with our species Homo sapiens throughout a long long period of existence in the lower middle Pleistocene this became known in the 1940s and 50s as the pre Sabian's theory the idea that there was very very early modern human looking population that it existed in parallel with Neanderthals how it was responding to that by saying look the evidence for this he uses the word downright flimsy I don't think we can get away with publishing this anymore about people it's downright flimsy evidence that there's some deep deep lineage of modern humans he says if you look carefully at Neanderthals you will discover that there's much more complexity than people have been giving this credit for and how is the issue that I started the lecture with how old raises the issue that there's confusion about what may endure tolls are how old tried to address this confusion by delineating different kinds of Neanderthals he says there are classic Neanderthals those are the Western European things like LaChapelle oh sad like la Pharisee like like the Gibraltar skull these are classic Neanderthals and the classic Neanderthals represent an anatomical extreme that is not closely connected to modern people anywhere in the world and has its own sort of European identity but when you look at earlier Neanderthals like the cropping a sample like the sample from Sacco pastori what you see is less development of these very specialized looking traits and more sharing with modern humans so that these early Neanderthals here he places them here these early in the and earth halls are a stem population potentially for both the classic Neanderthals and some modern human population so he says where are you having a turtles originating is in this phase where you might well have early Neanderthals in some sort of evolutionary stage point of view that are represented in other parts of the world where we haven't found them yet and some of those populations gave rise to us modern humans through a process of sapien ization and we see the evidence of that manifested in the Levant in sites like school and coughs ax and we see hybridization between school and coughs ax and more Neanderthal looking people which gives rise to things in his day like Ted Boone and as a consequence you have this sort of late origin of Neanderthals right and he points to evidence of this he shows how you have in classic Neanderthals so you have this very straight malar border here and in an early Neanderthal like seconds the story it's more human-like in its Anatomy he shows by sagittal cranial outlines right his sack opa story is the dotted line here which has this sort of less extreme elongation than LaChapelle o san Samanta church ARA - classic Neanderthals he shows early Neanderthals are not like the classic Neanderthals and early in the an turtles are a potential intermediate in some way and maybe represent an ancestral population - both right let me also say he also looks at the Levantine populations and the amid skull was not available I think to him at that time but I'm using it here as stand in because you see that here's a mood compared to school five which you know are not the same but share quite a lot of similar morphology here's the mood school compared to sack up a story which is an early Neanderthal and howls point of view his point of view on Levantine Neanderthals was that they also were a less extreme population possibly the result of hybridization between early Neanderthals and modern humans okay so that was how old's point of view this point of view I think you can see today is very much like it's not identical to but it's very much like the point of view that we've heard from genetics in the last ten years you hear people writing about the genetics of Neanderthals and the Anatol origins they ten years ago eight years ago we're writing about a relatively late origin of Neanderthals Neanderthals diverging from modern human lineages the African ancestors of modern humans in that point of view something like two hundred and fifty thousand years ago that early Neanderthals like crop inah would be after that time but they would represent a less extreme version of the Neanderthals that ultimately would come to exist in Europe and maybe some of these earlier slightly populations are common ancestors of human modern humans and Neanderthals something like the Sima de las casas right sample would be something like a common ancestor that was a very common way of talking about the genetics something like eight years ago all right oh yeah here's sutiya now may be something like two hundred fifty thousand years old and something that how old would put in the ancestral pop today now I want to talk about phylogenetics you saw some trees in the last lecture I'm gonna show you a couple of trees in this lecture and I don't want you to take any trees seriously the dinosaur tree takes seriously that's 100% the work of really serious people the hominin trees I don't know the ones that the work of serious people maybe you shouldn't believe so so here's a tree and this tree has the major defect that there's a couple of things on it that I want to talk about in a while that aren't on it but it has the major advantage that I've put question marks in a lot of places because we really don't know I'm going to talk about the question marks in just a second but here on this tree just to orient you we have Neanderthals on the tree we've got archaic humans in Africa on the tree we've got modern humans today's humans on the tree we've got Homo erectus on the tree and Homo floresiensis is on the tree and Homo Naledi is on the tree and they're more or less in time sequence right the the deeper in the tree you go the older you get it's hard by putting blobs that represent skulls on a tree to get time precise so I haven't even tried but you've got also these robust australopithecines and Milford talked about in this last talk you've got these earlier sort of species that are attributed to homo here you've got off for conness here ok so Milford's point of view these guys would all be homo in other people's point of views maybe these guys are homo or maybe these guys are homo and why is this here instead of being at home oh right we are divided about where to divide homo from the rest I'm not gonna go into that I want to focus on these last parts of the tree and I'm gonna show you a couple of cladograms now these are the results of a recent study that our work our team did on homo Naledi and so a homo Naledi is pink here and it's I left it pink so that I could show you how its position changes this is a tree that's based on looking at skulls and teeth of all of these different forms and the skulls and teeth are not the whole skeleton but the skulls and T's are all that exist of some of these forms right you guys saw Homo habilis is almost entirely represented by skulls and teeth rudolfensis there's no post cranial material that anybody's ever called rudolfensis some people would not call anything robot rudolfensis right so there's some uncertainty in what goes into this what I want to point out here this is a parsimony tree this is a tree that you would get if those of you who've done parsimony analyses in 1995 if you took the characters from this stuff and put it into palp and plugged it out and drew the results in Mack clades right you would get this tree this is a parsimony tree and the parsimony tree has humans today modern humans and Homo heidelbergensis as sister groups Neanderthals as an out-group to those two so humans are connected to heidelbergensis it's got erectus all together here and it's got some early forms of Homo together here with Kenny anthropos that sample from Kenya from Lamech we that you saw and and Homo Naledi is way out here as sort of an out-group to the rest of Homo except for the hobbits except for Flores the ANSYS okay now the entire reason for going through this is that the next tree that I'm going to show you it's totally different this tree is based on the same data set entirely the same day there's no difference in the data the difference in this tree is that they've used a Bayesian model instead of a parsimony model and the difference between those will be important too maybe one person in the room but most of you the only thing I want to point out about this is here you've got well Neanderthals in heidelbergensis our sister groups and modern humans are out to them and then you've got Homo antecessor connected to them and then the Letty is actually with these derived humans the big brained ones and you've got erectus is more distant and then you've got to get as Flores ANSYS look at this here's the species has completely changes position in the tree right what does this tell us it tells us that this species by the way is the one there where there's all the data right so lots of data for this lots of data for Neanderthals lots of data for modern humans lots of data for erectus honestly a pretty good amount of data for Flores the answers for that matter the fact is that even for the best fossil samples that have the way that we analyze the tree gives us totally different trees this is a hint that the data on which of these fossils are related to each other are not very convincing that's where I want to go with this I wanted to just point out the fossil evidence does not tell us with much resolution which species are close relatives of each other now these trees those two trees share a couple of features right the big brained humans humans Neanderthals and heidelbergensis are grouped together in both trees that's probably genuine if you asked me what are the closest relatives of Neanderthals among all the hominins I would say well probably today's modern humans and other archaic humans that have big brains are probably the close relatives right this is maybe not a surprise but the fact is that we can't say anything more than that the phylogenetic approach doesn't tell us who the ancestors of Neanderthals are all of these confidences in all of these right this is the one that has all the confidence the one that groups those three that's why I say it's sort of replicable the others are sort of miserable the other ones are not replicable a slight difference in the data would result in a totally different tree a slight difference in the method of analysis results in a totally different tree so as a consequence the anatomical data that we have from Neanderthals from modern humans from African archaic humans from Homo Naledi from everybody is not good enough to tell who's related to whom that really sucks all right this is where the geneticists come in right because the geneticists would say we know who's related to whom we've done their DNA it's just like ancestry.com for hominids right we know who's related to whom and here's a tree that represents 2015 knowledge of the genetics of Neanderthals Denisovans modern humans and and other things right and here's the salient feature of it we have today's people all on one branch of this great genetic tree we have a second branch of this great tree that has two big populations on it all of the Neanderthals that we know about are one of them and all of the sequences that classify as Denice Aviles are on the other one and in addition to that we have evidence from genetics of mixture among these branches all right so the Neanderthals contribute to here's Neanderthals contribute to the ancestors of all these populations who don't live in Africa today and the Denisovans somebody not this sequence that we actually have but a mystery sequence that is a sister group of that one that we actually have contributed something to Australia and New Guinea and so on populations and that branch has a big input from somebody that we haven't found yet this is the ghost population right that diverged at the very base of this tree and contributed to Denis Evans but not to Neanderthals okay well I believe in ghost populations I do right I see ghosts and I'm gonna talk about more ghosts but I will say at the outset the ghosts are a consequence of a model and we should be aware and cautious when the model generates ghosts right because the beauty of a model generating ghosts is it gives you something to predict right I predict there will be ghosts I predict that there were other populations that were quite genetically diverged that contributed to these populations that's a prediction and that prediction can be tested by finding them right that's wonderful we'd like that but there are possibly other explanations that might diminish the importance of these ghosts or make them disappear entirely in some cases and that's something to keep in mind that there's an assumption that underlie these models okay now it's the first thing I want to say before I go terribly far into this is that humans are not weird humans are weird in some ways but in this particular way the fact that there are deep branches the genetically quite divergent from each other that mix with each other sometime during the Pleistocene this is not weird this is the tree of chimpanzees using the same methods right here's bonobos here's central eastern western chimps and in a population that is sort of geographically intermediate between East and West chimps and what I want to show you is that these branches go back in time among the chimpanzee subspecies today here's a hundred and thirty nine two hundred eighty two thousand years between eastern and central chimps here's two hundred fifty thousand years between Western and this other branch of chimps here's five hundred to six hundred thousand years between those two big chimp divisions and something like one and a half to two million years between chimps and bonobos and after that time all of these branches have some hybridization among them so the fact is that this is actually the universal pattern that we know of for mammals every mammal lineage that has been examined so far with contemporary DNA or ancient DNA including extinct ones like mammoths and extinct is the cave bears right earlier this year we discovered the cave bears contribute to brown bears the brown bears mix with cave bears those of you who are archaeologists who have to worry about the cave bears and brown bears understand there are hybrids in your future they're coming because the fact is that these guys all mix with each other rarely and that's the other side of this picture that mammal species do have these deep lineages within them that are genetically sort of they had time to become different from each other that interbreed with each other and they do breed with each other on the order of something like 3% or 2% or 7 to the minus fifth power percent that's not very much but the 16 percent is the highest here right so so yeah they interbreed with each other on a percentage basis so hominids the tree is not weird right the tree is actually perfectly ordinary what's informative about the tree is the divisions that we have found but the divisions that we've found are not necessarily the divisions that existed and these ghost lineages I'm gonna talk about a couple more of them in a second give you hints of that that their divisions we haven't found yet okay now some things that we know about in the inter tal variability from genetics today first here's the denisa vez this is a PC plot and there's nothing particularly important about it except that you see that the biggest difference among these sequences the PC one difference is the one that separates Denise OVA from the from all the things that we call in the an turtles this is why the geneticists call them Neanderthals the geneticists do not call this specimen in the andert all because of its Anatomy it is a toe phalanx right the geneticists call this a Neanderthal because of its gene sequence if you set it up with Denis Simmons and other Neanderthals it consistently looks more like the other Neanderthals but when you look at the second component of variability among the sequences but you'll see is that all the rest of the in Turtles sort of look a lot more like each other and this one looks really different so the fact is that Neanderthals as a category being used today by geneticists and I'll blame the geneticists for this because the fact is the anonymous did not introduce this problem of toe classification right the the anatomist would not have said oh my goodness this toe bone isn't an turtle now you and I both know all of us know an anatomist that would say that and so I don't want to I don't want to go overboard right there are some but the toe classification is not very effective the genetic classification could be effective but note that this sequence is actually quite different from the others now we'll talk about that for a second it's been known now this is a 2012 paper from lova Delon this is it's been known now for a while that Neanderthals encompass more mitochondrial DNA variation than living people do now I want to be really precise about that because you'll hear other people say the Neanderthals are much less variable than living people are both of these things are true but the way that we measure variability differs in different contexts right if we look poorly at mitochondrial DNA sequence divergence we look at later in the and earth halls in Western Europe and they're all sort of they look like some very tiny human population in terms of their variability but if we broaden that and look at earlier Neanderthals and the an turtles that live in other parts of Western Asia you find that they're much more variable if we look at the nuclear genetics we get a similar picture right we have later Neanderthals largely in Western Europe that are all sort of close to each other then you've got some central or some Western Asian where I guess you'd call Ukraine very Eastern European sequences that are a little bit more different from that and then you've got this Altai sequence which is actually really different if we broaden this to look at the mitochondrial picture which has many more samples right it's narrowing in terms of what we're looking at this broadening in terms of representation what you discover is that well yeah this Western European sample is all really really similar that encompasses less variation than today's Gibraltar population for sure in mitochondrial terms but if you broaden that and look at other Neanderthals from earlier in time and from other places you see oh they're much more variable and when you look at this Altai sequence and the Holocene städel sequence whoa there are these really divergent branches of Neanderthals out there and then when you look at Sima Dilys way so switch in nuclear DNA terms was it on that last chart no but if you look at it in nuclear DNA terms it branches with the Neanderthals it doesn't branch with adhesive ends it's got a totally different mitochondrial sequence it's mitochondrial sequence is closer to Denyce offense but it's not close really to anything you've got a complete replacement of mitochondrial DNA as far as we know in Europe and Western Asia among the Neanderthals in other words we look at Neanderthals we are interested as scientists as anthropologists we talk about Neanderthals as if we're talking about this empire that existed from the Altai to Gibraltar and was contiguous over space and represents populations that were forming a race right they were becoming really really different the fact is that that Empire was full of different populations that lived at different times that were actually much more different from each other than any living people in that region are from each other their comparably different from each other as any living people in the world are from each other right from quois on to Beijing that difference in genetic terms is the difference that we have among meandered halls in genetic terms so it's sort of crazy level difference and that difference has gone through a succession over time with mixture and input in significant ways from other populations so this chart from a 2016 paper was one that demonstrated that there was a stem population of modern humans that contributed DNA into this altai neanderthal population but not the others again this estimation comes from a series of assumptions and models I don't want to take it too seriously what I want to say is that it's not true that Neanderthals didn't get DNA from us in fact and the an turtles got DNA from modern African humans multiple times during their evolutionary history not only in the later phases right this is estimated at something like a hundred thousand years ago so you imagine those school and coughs uh critters running around and sending their DNA into the Altai that's the timeframe we're talking about but remember the C model is way so sample has totally different mitochondrial DNA from any later in the and hurtles how did that happen how did it come to be that today's people are the closest sisters of Neanderthals in their mitochondrial sequence when I'm sorry when Denis events are the closest sisters of Neanderthals in their nuclear DNA sequence in fact we know how this happened the reason why up until three or four years ago the geneticists were talking about a recent origin of Neanderthals was because this deep dataset of mitochondrial DNA shows that Neanderthals are close to modern humans and the only way that can happen is if the mitochondrial DNA had branched recently between the and earth halls in modern humans something like 400,000 years ago so as a consequence the idea was that Neanderthals in modern humans siblings are separate raised 200 250 thousand years ago we had this recently a turtle origin today we appreciate that genetics of the nuclear DNA tell us that know the origin was much older and involved this Danny 7 population which is really separate it has to have been deep the only way to square that circle to reconcile those two observations is for Neanderthals to get their mitochondrial DNA from African modern humans or for African modern humans to get their mitochondrial DNA from Neanderthals one way or the other we don't know which so there's a deep episode of gene flow in the origin of Neanderthals from African populations or to African populations that occurred sometime before 300,000 years ago so you've got this history of successive population mixtures which have contributed in a meaningful way to what we today can see of the genetics of Neanderthals right I'm not just talking about trivia this was the data on Neanderthals before 2010 the mitochondrial DNA everything that anybody wrote about them genetically before that was based on this and this is an intra gresham that came from elsewhere okay that's pretty cool right that's that's a really exciting observation that we've got this deep mixture and then it contributed to what we understand of Neanderthals it is a way of saying that among the ancestors of Neanderthals our African populations from the Middle Pleistocene that's important right African populations of the Middle Pleistocene are among the ancestors of Neanderthals in the same way that Neanderthals are among our ancestors it's precisely analogous we've got things from Neanderthals because they're our ancestors it is an unfortunate thing that anthropologists everywhere must train themselves to talk about our African ancestors and our Neanderthal ancestors it cannot be modern humans and Neanderthals that's not a meaningful concept in genetic terms it is our African ancestors and our Neanderthal ancestors and potentially other our denisa vain ancestors right our potentially other ancestors so let's look more deeply into this Allen Rogers last year did a really cool model about Neanderthal origins and adhesive in origins and the really cool model was accompanied by no useful figure this is very unfortunate for someone who wants to present the model and so what I'll say is I want it I want to summarize this model because what this model has is an origin of Neanderthals around 600,000 years ago with a lot of error right all these genetic estimates have a lot of error a rapid spread of Neanderthals and a rapid diversification from Denyce events within a span of 30 or 50,000 years so you have what happened in the earlier Middle Pleistocene was precisely the same as what we think happened in the Late Pleistocene except with different actors involved you had a Neanderthal ancestral population that rapidly spread and diversified that became sort of genetically differentiated that spread into these different populations and as a consequence inhabited most of Eurasia well that's a great model I like it every archaic group that we have sampled interbred with others often much more than we appreciate right this is a really really bottom line statement but let's come back to this hybrid because if it is true that Neanderthals originated a long time ago deep in the Middle Pleistocene and that Denis Evans originated also sort of deep in the Middle Pleistocene and that these populations existed for a long time that's convenient as an explanation for why we can tell the difference between them so readily in genetics right they are actually genetically pretty different and the Neanderthals by the way are also genetically pretty differentiated so we know that there's been time involved in their separation in their diversification but we also know that they hybridized with each other with us with other populations repeatedly we know in evolutionary biology that these two facts are a contradiction you cannot have diverging lineages become really different if there's lots of gene flow between them so what explains this how could it be that these populations that are spreading and able to exchange genes with each other and who are cosmopolitan as Millford says able to spread effectively and evidently able to transform over time within a region with some serfs pretty substantial genetic turnover how could these populations also maintain the kind of genetic difference that we see well there are some ideas about this right one idea often associate with robbing dental is something I've written about something others have written about as sources and sinks there are areas of the geography that have you know sort of reproduce more in areas of geography that are not really great for long-term habitation and these establish Cline's that actually are long lasting even if hybridization happens a lot I like the idea and we don't presently have great evidence about it but I will turn for a minute human populations are invasive human populations are resilient right and these are somehow contradictory to each other and I want to show you how this plays out in Africa all right African modern human populations we today know a lot about their variation we need to know a lot about their diversity today and one of the things that we know is that there were groups as different as Neanderthals and Denisovans that interbred with today's African population ancestors these are the African ghost populations they existed as long ago as the early Middle Pleistocene and quite possibly earlier their sign is visible when we look at across the genome when we look at different areas of the genome and we look at how differentiated individuals in African populations are at different areas of the genome so that most of their genome has this sort of low level of differentiation a half million years or something like that but some parts have much greater differentiation and those parts that have greater differentiation in their genetics are parts where some of the genetics has come from a diverged population we also see the signs of this in today's genetic variability here our hunter-gatherer populations in Africa who have much more hetero zygosity that's much more genetic variation than anybody else but in particular if we look at a chart like this I'm going to show you these MCMC plots tsmc plots sorry this is everybody outside of Africa today sort of looks like this what this is is a chart that at different times in the past attempts to give a representation of how big the population was at that time in the past relative to today so here's 1.0 scale to today here's less here's more what you see is that everybody outside of Africa has this time when what looks like genetic variation was really really low right and here it's in the time scale about 50,000 years ago I don't want you to take the time scale super seriously we don't really know if this is a hundred thousand if it was thirty thousand but what we do know is it's shared that signal is shared by everybody outside of Africa that signal it's here plotted in terms of effective population size but what effective population size is as a measure of inbreeding how inbred are these people everybody outside of Africa is inbred in this timeframe however when you look at hunter-gatherer populations in Africa you see that that time frame where the French have this huge inbreeding these hunter-gatherers don't right this is one of the big signals that you have some sort of bottleneck that has affected these populations outside of Africa now people talk about the spread of humans Out of Africa that sort of thing this is this data that supports it in Africa the hunter-gatherer populations don't have that strong signal but if we extend this further back in time here's the non African populations and their big bottleneck looking thing here's some African populations and their lack of a bottleneck here in the adder tall's and Denis events and you see that through most of their history they look bottlenecked and that's reality if you look at these genomes they look like they came from a tiny population they look like a population that was highly inbred if you look deep into their history they start looking less inbred until finally they share most of the signature that we see in in other human living human populations and that time frame is sometime long before these sequences that exists in the Late Pleistocene right so sometime in the early Middle Pleistocene their history merges with ours but after that they're super inbred the fact is that the population structure of this eurasian population denis ovens and the and earth halls and anybody else that might have been there that population structure was one that was divided into very small units very small populations that interacted with each other less frequently they were less out bred right modern humans today are weird I said it earlier we're not weird actually we are weird we're weird in one way we're weird in that today we're really really out bred our recent ancestry in some populations was not that was inbred and in other populations was that was out bred but our ancient history was much more inbred all right we know this from the fossil record this oh yeah yeah skip the ghost population there's some reasons think they're ghost populations we know this from the fossil record because when we look at early African modern humans there's I want to show you this the things that we look at and try to say this is the origin of modern humans no this is the origin of modern humans no jebel irhoud is the origin of modern humans no homos the origin of modern humans right we all want to have the first modern humans the fact is when we look at these actual specimens they're all really different from each other and they don't share the same things with us they're really diverse and that diversity is a sign that Africa was also in our early late and late Middle Pleistocene timeframe genetically diversified into inbred populations that were actually quite different from each other it's very popular today to talk about African multi-regional evolution I like this it's wonderful but it's a very different type of picture then you would get if you took today's population structure and extended it back in time in fact the population structure at this time was quite more diversified than ours is with less intermixture at a distance among populations than ours is which is one possible sign that you could have things that we haven't discovered yet like ghost populations now if I wasn't involved with discovering one of these I might give this less emphasis but the fact is that we have things in Africa this is Homo Naledi that existed in the middle and later Middle Pleistocene that look like they represent really old lineages that were there for a long time so that kind of differentiation in Africa which includes what people claim to be the ancestral population of modern humans also includes really diverse things so the diversity in the past was much greater than today in population terms but the diversity in the pad within populations which much less than today vastly less okay so where do I go with this I told you I wasn't gonna tell you who the ancestors the Neanderthals were alright I'll tell you it's not Homo heidelbergensis I'll just skip it I'll tell you that these guys right Sima de los huesos this incredibly wonderful sample right which genetically looks like an earlier branch of the Neanderthal lineage right here's Neanderthal scenarios and this is what people would have said ten years ago see MIT ELISA waste those branches off from somewhere the common ancestor of this Neanderthal and African peoples today is quite clear that Sima de las casas branches off from an earlier branch of the Neanderthals and that this all goes deeper in time that's true Sima de lo sway so this is fundamentally in the and earth all we can ask who's the ancestor of Neanderthals Homo antecessor right is something that people talk about from a de Puerco also from Grand Elina and there's reasons for that if you look at the specimens they share a couple of features with Neanderthals but that sharing of a couple of features is one sign as we have seen that can also be attributed to population mixture if we actually have these populations that emerge that become genetically diversified then mix every so often we will see this kind of increase over time the maori sample Arago sample out of work a sample of Neanderthal traits if we look at one delineated part of the world right our bias is that we've looked at one part of the world and we've asked where does this trace back to we should recognize the bias that comes in from looking at one part of the world and tracing it back is that we'll find the features that characterize that part of the world in their earliest manifestation all right so yeah this is one scenario this is the Burma dos de castro scenario of we've got the first Europeans that branch off the homo antecessor the branches off there's a main stream and the andert alls branched off later and I don't want to give them a name because you know maybe they're heidelbergensis or something and erectus is branching off way earlier I don't know I don't like it I'll tell you what I think I think that a lot of people when we talked about the origin of Neanderthals are sharing assumptions that I don't share one of those is that the European record has little to do with anywhere else I actually don't share that assumption I think the European record is very relevant to a lot of things it doesn't mean it's the ancestor of everything it means that it has relevant to unwell events to understanding what is on other places and then the and earth halls are no less a case of that Neanderthal variability tells us about population structure broadly because it's a characteristic of the population structure broadly Homo erectus is irrelevant because he nobody talks about erectus and the Anatol origins anymore I don't share that assumption and African Homo sapiens populations were more fluid than Eurasian homo populations that's something a lot of people share is an assumption I don't believe it I don't believe that there's something different about Middle Pleistocene African populations in structure I think that their structure is comparable to what we see with Neanderthals and Denisovans okay so that being said who are the ancestors the Neanderthals I think we have to bring a lot of these characters in right we know for instance that Asian Homo erectus right Shoko chen is part potentially the community that's contributing to the Denyce of and population this ghost population concept we can't rule out these guys they could be the ghost population here's a potential ancestor this skull from Dhaka from Ethiopia an African later lower Pleistocene skull about a million years old where are we looking for the ancestors of Neanderthals we're looking for a population that existed before 700,000 years ago that population might have been like this and this the booyah skull from Eritrea again similar age similar geographic location but we know that these later populations were among the ancestors of Neanderthals because we know that the gene flow that entered the Ender tolls from other places came to them from populations like this so we know some ancestors from Neanderthals we don't know them all this is the other million year old thing in Africa I like this one this is from a logrus i'li it's a very small brained very primitive looking thing is it among the ancestors of Neanderthals is it among the ancestors of Naledi is that one reason why Anna Letty is hard to place right these are all questions I think we have to have in mind okay so that's where I want to stop
This was Sept 2018, right?