Brave New Prehistoric World

foreign we're going to take a new look at this old family portrait you know it's the one that many of us grew up with and so you might say this is the story of A Brave New prehistoric World a story of cutting-edge Science and heated debate about the evolution of our species homo sapiens to get us started here is a quick timeline it was around six to eight million years ago that humans and chimpanzees branched off from a common ancestor and from then it took about another four million years for an adventurous group of archaic humans called Homo erectus or upright man to leave Africa now this group spread across a wide swath from southern Europe to Eastern Asia and were last seen at least according to the fossil record about a hundred and eight thousand years ago in Indonesia that timing probably overlap with that of early Homo sapiens but fossil evidence seems to put them in different Geographic locations so whether members of the two groups ever met that is still an open question now all of this was going on in what archaeologists call the middle to late Paleolithic a period that has yielded stunning discoveries in just the last decade we've learned that between roughly a hundred thousand and fifty thousand years ago at least six other groups of early hominids walked the Earth at the same time as Homo sapiens the previously much maligned neanderthals a group in Asia called the Denise events at least three different groups of hobbit-like humans in South Africa homo naledi in Indonesia homo floresiensis and in the Philippines homo luzonensis and recently we met a member of yet one more group in China called homolongi fondly referred to as Dragon man and it turns out that's a compliment in North America we also learned that a haunting set of footprints in White Sands National park likely belong to a group of early humans who lived there before the last glacial maximum or Ice Age which is tens of thousands of years before conventional wisdom placed human arrival in the Americas is it time to completely re-evaluate who we are as a species what Have We inherited from those long-lost ancestors and what can they tell us about ourselves we are joined today by four researchers whose approach to these issues come from a variety of different perspectives and who bring the tools of different disciplines to Bear upon them joining us from Vienna Thomas hayam professor of evolutionary anthropology at the University of Vienna from Doha Sheila athrea a paleoanthropologist at Texas a M's campus in Qatar joining us from Jerusalem we have Vivian Sloan the head of the ancient DNA Lab at Tel Aviv University and from Cape Town South Africa Rebecca Ackerman who is the founding director of the human evolution Research Institute at the University of Cape Town welcome to you all thank you so much for joining us there is incredible amount of excitement in your field rapid changes over the last 10 years so I'd like to start by asking each of you what do you consider the most exciting work that's happened being right now in the study of human Origins let's begin with Vivion just the ability to recover DNA from archaic hominins neanderthals Denise events I think is very exciting it's something relatively new only a couple of decades that we've been able to do this and we can now do this to the extent where we get data from the entire Genome of individuals that live tens and even hundreds of thousands of years ago so I think there's a lot to be discovered and it's an exciting field to be in Tom how about you what would you if you were going to write the headline for the for the globe mail or whatever your favorite newspaper is what would you say um well I think Viviana has hit the nail on the head as far as I'm concerned to me the most exciting things over the last decade or two has been the um the Revolutionary information that we can now glean from ancient genomics this gives us the opportunity to look at the the on the ground situation in terms of the distribution of these various actors that we have in the uh in the field of human evolution Becky how about you what's your take on that question so my take is that I think the most exciting thing is that it is showing us everything that's happening in the field is showing us how complex the origin of humans is that it's not a simple narrative and that we're not talking about you know as you as you introduce one group coming out and conquering everybody else in fact it's a much more sophisticated um thing that's going on in this space and related to that I think that's allowing for the emergence of frankly people paying attention to regions of the world that they hadn't paid attention to before and I think long term that's going to be a really important part of our increasing understanding of these sort of complex Origins Gila thoughts on that yeah I would say it's a bit of what everyone else has said so far um which is that it's a combination of um the research that's coming out of areas that have historically been underrepresented or or actively marginalized and specifically I'm thinking about east and south East Asia but also the tools are getting better to get information from the materials that are in environments that don't preserve very well and so the work that viviane and Tom do allows us to get information from remains that historically we wouldn't have been able to to get any information from you know I have heard maybe this is apocryphal but there was a time when folks tried to date bones fossils by licking them the tongue would stick to the old ones and not to the new ones I I presume we've gone beyond that substantially by today maybe we can start with radiocarbon data I think many people are familiar with that but just give us the basics of that and then we can talk about how you've been pressing that field forward okay sure so um well radiocarbon is um one of the most important techniques that we have for dating the archaeological past there are some problems with it which we'll we'll touch on but one of the main problems is that it runs out at about 50 000 years ago and that's that's sad because it's just about that time that the late period of human evolution becomes super exciting we have to rely on on a on a new range of other dating techniques that include other types of isotopes that we can use to measure and other types of techniques that allow us to add um to to the dating of of archaeological sites because of course dating is critical in archeology looking at you know the presence and absence of humans and their relationships with other types of humans it's all predicated upon having a robust chronology and we need to know when things happened in the past in order to understand why they have happened and so radiocarbon and other techniques are crucial in this in this endeavor yeah sure now we've all seen you know whole bones and skulls from archaeological sites but I've seen images of some of the samples that you analyze and many look really tiny like like this little chip off an old Pinky bone and I gather that making things get more challenging sometimes these samples are actually contaminated with DNA from other periods is that right it's a big problem and it's been it's been probably the biggest hurdle in terms of the reliable application of this method so if you take for example a bone that's 50 000 years old and you imagine contaminating it with modern carbon that's in the soil for instance that will produce a radiocarbon measurement that's 13 000 years too young and so as we go back in time so the bones and other samples get more prone to this contamination signal and contamination effect we have to use quite sophisticated chemical methods to clean up the samples that we want to reliably date we have many many dates that have been produced over the last 60 years that are unfortunately we now know underestimates of the real age so so Tom for many years now you've been studying among other things Neanderthal sites across Europe and parts of Asia and and as I've read some of the research that you and your colleagues have done in these places it paints a very different picture of Neanderthals than we had up until I mean just a few years ago we we know now um to take Justin neanderthals as one example that that neanderthals far from being this really backward um slow dim-witted group we're actually doing extremely capable things and making making objects and artifacts and and Innovative Innovative tools and they were extremely well adapted um and that we had a very long period of overlap with neanderthals um and groups of Neanderthals in Eurasia um and and places like Europe and um the genetic Legacy that we have tells us increasingly that who we are today is really part of the legacy of these interactions that we experienced in the past and in fact Tom as I understand it the the latest dating indicates that neanderthals are engaging in these complex activities often tens of thousands of years before Homo sapiens even arrived on the scene in Europe so so before we go any further I'd like to share with our viewers some of the more extraordinary sites that that you and your colleagues have been studying one of the most evocative Neanderthal sites has been found deep inside a cave in brunikel in Southwest France somebody and more likely a whole group of somebody's working together arranged hundreds of charred stalagmites into two large circles this could have been the site of ritual shamanic or funeral ceremonies around 175 000 years ago since at that time neanderthals were the only hominids in Europe that is all but certain they were the ones who designed and built these remarkably complex structures in yet another cave in Spain a set of Neanderthal teeth tells the story of a young male suffering from an abscess and a stomach bug his tartar suggests the unfortunate fellow was self-medicating with among other things chamomile fungus containing penicillin and Poplar bark which contains salicylic acid the anti-inflammatory and aspirin neanderthals also had style these pieces of refined looking bone jewelry belonged to a Chic Neanderthal in France around 42 000 years ago more than 64 000 years ago sensitive Neanderthal souls in Spain were making cave art the stencil of a child's hand and these abstract patterns were made twenty thousand years before Homo sapiens arrived that was a long time before another Spanish artist from the same region Pablo Picasso made a name for himself not bad considering that when the first Neanderthal fossils were found it was suggested the species be named homostupidus and if all you homo sapiens out there are starting to feel competitive you can relax these Paleolithic prodigies Are All in the Family when Homo sapiens showed up in Europe and Asia neanderthals co-existed with them for several thousand years before dying out enough time for some of them to meet up and on occasion become intimate we know this because Noble Prize winners fonte pebo and his team have pioneered a new field called paleogenetics among their accomplishments they were able to sequence the Neanderthal genome when they did we learned among other things that today modern humans of European or Asian descent on average are genetically one to two percent neanderthal now Vivion that I gather is your field the relatively young discipline of paleogenetics sequencing the Genome of ancient humans which I have to say seems like an extraordinary thing to be able to do and in some cases from just a few slivers of bone I mean how much can we learn from such genetic data the most basic way that we can sort of look at DNA of ancient hominins and other organisms doesn't have to be hominins is that we would take a bone or tooth and and we would drill a little hole in it to recover some powder and then we can extract the DNA that is released into a solution by using chemicals that affect both the organic and the inorganic parts of the bone and that tells us what was essentially the genetic makeup of these ancient humans we can tell the genetic sex of course but we can also see which population that these individuals were derived from both on the maternal line that we know from a small part of our genome called the mitochondrial DNA but also genome-wide from both parents um we can tell about issues of adaptation for example genetic adaptation to different environments we can talk about kinship and social structure in ancient groups um and we'll I'm sure talk later on about sort of mating and movement between populations and when they met and the um and and intermixed so how how long can genetic material last in an ancient sample it's very dependent on the environment so if you're looking in permafrost the oldest DNA sequence that has been retrieved so far it's actually a study that came out just a few months ago comes from Mammoth remains that are of over 1 million years ago um but that's in permafrost where essentially the samples are in a freezer for the last million years going outside of permafrost in more temperate climates the oldest DNA we have so far is both bare DNA and human DNA coming from a cave in Spain called Sima de los huesos and these remains are dated to about 430 000 years ago and this is sort of the extreme um of what we can so far or what has been done so far um outside of permafrost I now work um in the area of the Levant where outside temperatures are quite warm and it's a problem for DNA preservation uh we are very happy when we can find a spot that is more than 10 000 years old you've gone beyond extracting organic material from from Bones and are also studying it in in just the dirt right in in the sediment at some archaeological site how is that going and is this is this an idea that when first put forward people thought was crazy or is it one that people like yeah that that that that might work when I got interested into looking into this to try and look for ancient hominin DNA it was considered one of the crazy projects because we all we thought all of us that it would be too hard to tell apart contamination from um from ancient DNA particularly when we were working with human DNA which is of course as ancient and modern has a lot of similarities um and so this idea of being able to take I would say a soup of DNA that you extract from a sediment so this sediment sample can contain DNA from plants and from microbes and from different animals and to be able to say something about that population it's Neanderthal it's Denise of and it's something else um no it was definitely definitely supposed to be a crazy project but we did a pilot study and we found that it does work when you can go to his archaeological site and Sample tens or even hundreds of samples and look for changes in the human populations through sometimes tens and even hundreds of thousands of years of History just by looking at elements so that's I think to me very exciting yeah it sounds hugely exciting we'll talk about some of the implications in just a moment let me turn to to Becky now there's this I don't know almost canonical story that many of us have been told at least those of us on the outside of the field that you know there is an evolutionary record in which species evolve they diverge they Branch off and and one of those branches over the course of evolutionary history ultimately resulted in us right I think that's sort of a familiar story that that many people have heard I gather there's growing evidence and your perspective is that that metaphor that framework really needs to be retired in some sense or at least updated in a significant way to include the kinds of of mixings that we're going to talk about more that we've already heard referenced to just give us a sense of where where you come down on on the right way of thinking about things I come down firmly in the braided stream kind of space so instead of there being just a branching and one thing leads through you have quite a lot more interaction and you have mergers through hybridization that results in gene flow that itself doesn't just bring things together it can also be the producer of novelty and new variation so gene flow if you can just uh give us a sense of what that term means because I know it's going to be vital to what we're talking about yeah so we've kind of used these terms a bit Loosely sometimes and and in fact the term that you'll see or you'll hear more often is hybridization essentially hybridization is the act right you have organisms coming together and mating so they're hybridizing when it comes to actually looking at a skeletal remain are there telltale signs of some kind of hybridization event in the past yes there are and that's some of the stuff I've been doing which is looking at saying okay let me look at other hybrids let me look at other organisms other mammals primates um wildebeest all sorts of things and can we see what that signature of hybridization looks like in the skeleton so that we can use those analogs to then look at the fossil record and see if we see those same kinds of signatures we can look again at the human fossil record and see some evidence for it are there any examples you can give just a sense of what sort of specific things are the signatures sure I can get example um so I've done a lot of work in baboons and when you look at baboon hybrids what they show is that when you have two very different slightly different depending on what what groups of baboons you're looking at genomes that are coming together but they're different enough that they cause developmental I want to say almost glitches if you will the little um lines in your face where your bones come together for example or a suture or on your skull um extra teeth rotated teeth so little small signatures that allow us to look into the fossil record and identify and this is important individuals who might be a hybrid and so when you use the word glitch what comes to mind for me is this kind of folk myth that by bringing together different animals different species somehow you create I don't know frankenstein-like Monster structures has that View which obviously comes from a very coarse reading of how the world actually works but has that view impacted the degree to which the possibility of these hybridizations has been accepted by the community absolutely yeah you know I I think that the community of the human evolution Community more broadly okay anthropology in particular has been relatively slow to uptake this for a number of reasons but the primary one is probably because the work on hybridization the good work on hybridization was actually being done um primarily in plant biology and it was kind of easy for people to wrap their heads around the idea of plants hybridizing I mean we hybridize plants all the time and then it moved to to animal biology but that was only you know sort of 30 years ago-ish where we started to get a real flourishing of our understanding of hybridization and animal animal biology and so that field was on top of it if you will but that literature um never really it never really got into paleoanthropology and human evolution so it wasn't really accessible in that way and on top of that as you said we tend to people tend to have this kind of idea that hybridization is bad that if you have hybrids it's going to produce an offspring that's going to be mutant or if not mutant at least um infertile right and that that essentially wouldn't go anywhere and what all these studies coming out of plant and animal biology have shown is that yeah that can happen you know sometimes you have infertile individuals sometimes you have reduced fertility sometimes you have um lineages that come together and merge essentially so it you know it basically collapses everything but sometimes you can have the evolution of new species through hybridization that are different enough from their parents that they maybe are adaptively different can succeed in different environments than their parents could sometimes you get the evolution of novelty in these new groups through new combinations of traits and these this kind of novelty and speciation is the um it's the the productive force of gene flow and of hybridization that hadn't been given attention before yeah we'll look at some examples in in just a moment but Sheila let me turn to you now your focus has also been in morphology but as I understand it you've also taken a more what might be called a holistic approach I mean we heard from Tom about radiocarbon dating other methods Vivion in terms of a genetic approach Becky in terms of maybe changing the Paradigm where we don't view it as just a tree-like structure but rather I think he described it as these these blending streams I sort of like that metaphor a lot so what's your view is there is there a new approach that really needs to take root in the field for the kind of progress that we all want to have happen to take place yes my frustration has always been the existing models that I have to put my work in so I'm very interested in middle and late pleistocene evolution in Asia um but the interpretive Frameworks available to me have been language that that just doesn't make sense to me so um you know the origin of modern humans and Extinction and um and the idea that homo erectus went extinct and was replaced I felt like I was doing like retroactive racism by saying okay these are pure and these are us and these are um other Asia wasn't just this recipient of evolutionary innovations that came out of Africa or even these evolutionary Novelties that came from Europe right it wasn't unidirectional that there was um in that the gene flow was was moving both ways and that um you know maybe some of the specimens that we're looking at in Central Asia or Southwest Asia or Eastern Europe um have also been shaped by gene flow from the East to understand if there's yet another Cranium that was found that's called homolongi or Dragon man this one was discovered in Northeast China and I've read that some of those who led the study I think it was Chris Stringer of the British museum have suggested that maybe homolonga is the closest relative to us in terms of the Paleolithic family tree so does that strengthen your view that we really need to think locally about our lineage is that another piece of evidence in favor of that perspective um that's a really good question and I would actually I make my answer might be unexpected to you which is no it doesn't strengthen it because you know this um comes back to um some of the work I do which really interrogates the language that we're using right I don't subscribe immediately to something being a new species just because it's been named as such one of the things that I think drives this idea that this is like us it really conforms to our understanding of what modern humans look like based on what what really what Europeans look like right and so it doesn't have a big brain does it have a globular head does it have smaller teeth and so rather than actually look at the fossil record in the early late pleistocene or the late middle pleistocene and say well what were the patterns of variation around the world at that time and let that be what defines us we take this type and then we search for it around the world there's a very fascinating correlation between major climatic events that happen that really shape China and the Chinese landscape at the time period that all of these fossils such as the um the longy specimen and some of the other things that were recently published from the site of shuchang and hualongdong um that are at least sort of what Becky you know works on um evidence that that there were things that would have relaxed um the climatic barriers and allowed for gene flow and you know could that be why we're seeing some of these new morphologies at this time period around 300 000 years it's a period of incredible warming and um and stability which really facilitates populations coming together and does any of this have an impact on when we should imagine Homo sapiens having arrived in Asia do those dates need to be revamped to be revamped is the idea that homo sapiens evolution is going to be this clean event and not a process Homo sapiens evolution is a process and so we can't name it as being a moment in time and an arrival in another place and so building on that thought Sheila I'd like to turn now to another set of discoveries that have challenged our previous View of early human history in Asia we've already talked about some surprising insights involving neanderthals in Europe before Homo sapiens arrived on the other side of the continent discovers in the altai mountains of Siberia give us a new picture of what was happening there and roughly the same time period Tom and Vivion you have been deeply involved in this but before we dive in let's share some of the story with our audience this remote region on the border between Russia and China is the site of the cave of denisova 2010 the team who had sequenced the Neanderthal Gene made a stunning announcement that radically changed the picture of early human history they had discovered an entirely new unknown group of ancient humans remarkably the initial evidence came from a mere sliver of Pinky bone its nuclear DNA revealed it belonged to a young girl who lived between 52 and 76 000 years ago the previously unknown archaic humans were named denisovans after the cave where the pinky had been found [Music] the Denise Evans like neanderthals turn out to be some of our long-lost relatives their DNA shows up today primarily in populations across Asia and Oceana but Denise him and jeans have been found in people as far away as the Americas when Tom hayam and a team of Russian and Australian researchers sifted through fragments of prehistoric trash in the Denise van cave They concluded Denise Evans lived there as early as 200 000 years ago and maybe earlier these previously unknown relatives of ours were making jewelry and tools and living in this remote corner of Asia for hundreds of thousands of years before Homo sapiens arrived on the continent but Denise events are not the only archaic humans who lived in that cave other bone fragments found them revealed they may have shared it for a time with neanderthals starting around 170 000 years ago at first it was unclear whether or how the two groups interacted then in 2019 Tom hayam and Vivian Sloan were involved in another astonishing discovery carefully searching a bag of prehistoric rubble from the cave a member of Tom's team Came Upon yet another finger bone fragment less than two and a half centimeters long Vivian salon's DNA analysis of this fossil made headlines she found it was that of a 13 year old girl whose father was denisovan but whose mother was Neanderthal they named her Denny the fruit of a liaison and that Paleolithic Penthouse some 90 000 years ago Denny is the first fossil of a first generation human hybrid ever discovered so this all kind of has the makings of I don't know you might think of it as a a prehistoric Thriller right a kind of enticing detective story if you will you've got these remote caves in Siberia in Tibet you got layers of human habitation where groups we have identified as different species and we can come back to that they're living together apparently they're let's say it's sleeping together you've got a trail of genetic hybridization that reaches across the Pacific right Vivian and Thomas begin though with the discovery itself Tom can you talk about your work so the work that um that I and my team have been involved in really stems from um a conversation and a meeting that took place at Denise of the cave itself between um several colleagues as it happens my wife and my co-researcher Katarina duka and I and we were thinking um over the course of several days whilst we're at the site of this tremendous problem at Denise Denise of a cave has been excavated since the early 1980s and there are thousands and thousands of bones that have been dug out of that site and of course they um they provided in some cases these tiny human remains these very very small pieces of bone that have the great benefit of having lots and lots of DNA and most of them you could fit the bones of the denisons from that cave on one on on your hand and most of the bones more than 95 of all of the bones excavated at the site are tiny fragments that we simply don't know um the identification of we don't know which species they are they could be Mammoth bones hyena bones you know cattle bones we have no idea but amongst them lurk some undoubted human remains human bones are of the kind that have already been identified by some of the archaeologists there so we were thinking well how could we take advantage of this tremendous source of information this tremendous uh preserved DNA Legacy how can we find these human remains and so we fixed upon this recently then recently discovered technique of zoo Ms so um zooms or zooms it's um it's an acronym that is used to describe a really exciting new technique which takes advantage of the fact that in different animals and different species of animals there are very slight differences in the proteins and the peptides that make up the collagen part of the bone collagen and proteins generally have a fantastic advantage over DNA in some respects in that they survive for much much longer so many more millions of years than the um than the DNA that Viviana was talking about before and we thought well what we could do would be to take a whole bunch of these bones take them back to the lab and just analyze every single one of them and see whether or not any of them have the fingerprint the protein fingerprint of of a homina day of the the broader Human family and Samantha Brown who was the student that took on the project in our lab in Oxford she worked very hard to take small samples from each of the bones and number 1227 gave us the characteristic five hits on these peptides that told us this was a bone of of a human but what human we we couldn't tell so this this little fragment um like like how little is little are we talking about here yeah well we're talking 2.4 centimeters um so you can see that it is um it is really small and it's completely nondescript you would never know that it's a bone of a human it could be from anything but the other peptide sequence told us that it was uh it was from uh from one of the Human family um but uh that is as far as we could get with the uh with the peptide with the peptides we really needed the DNA extracted to tell us exactly what it was but yes it's a tiny bone nondescript and from a from a bag of bones of thousands of bones that we can't tell apart so once you've found it I mean did you put that in a vault or something how do you ensure that that little fragment uh stays with you so we put it into a special um yellow briefcase that that Sam used to used to carry around it's in my office here yeah no no I'm serious yeah I still have it here it's the bonus there I'm going to take it back to to Russia to um to to give it back to my Russian colleagues because um they store all of the human material from the um from the Denise of the site there but I just haven't been able to get there for the last few years so um because of covert obviously so um it will be repatriated to um to its friends uh in Duke that is good to hear so Vivian you took it from there so you got a hold of this little fragment of bone and it was up to you to try to use these DNA techniques so what happened so yes I was lucky to be at the right time with the right place in Leipzig where Sam arrived with her little yellow suitcase with the bone in it um and so we sampled it together and the in the clean room uh at the max plant Institute in Leipzig and we extracted the DNA it got sort of the official name of denisova 11th or the catalog number uh of the 11th human remain from denisova but as Tom can tell you they had already nicknamed it Denny in the lab and so uh Denny is what we often uh call her something very unexpected happened is that we found that she matched both the Neanderthal variants and the Denise of invariants in almost equal proportions so we had found this individual that had both Neanderthal and Denise of An ancestry in almost equal extents um were you shocked today were you shocked about this were you surprised by that result could it have been just the result of contamination yeah so that was actually my first thought was oh wow did I do in the lab did I mixed samples up like how is that possible um and for for quite a while I was very unsure as to what the signal um was due to um I do remember that the first time that I presented it in a lab meeting and I was like hey people look I have this half and half and people were sort of throwing around the word hybrid as a joke because nobody thought this was possible that we would actually come across a mixed Offspring and make a sort of a mixed Neanderthal denisovan and I was certain that there was something wrong that there was something some mixture happening in the lab some some human error and so we went back to the Bone and we sampled it again and again and again and a total of six different times six different experiments uh sort of from the beginning all the way till the sequencing um and again and again and again we saw this this analytical picture of half nanitol half denisovan and just to be sure this wasn't happening with other bones that we were working on in parallel so it wasn't some kind of technical problem that was affecting sort of everything we're working on this is really only this individual and then we had okay so then you know you start believing it happens over and over again so it does seem that this individual has both Neanderthal and Denise of An ancestry we saw that the scenario that is best supported is the fact that she had one parent of each group and so since uh we know that she has the mitochondrial DNA so what's coming from the mom that is neanderthal-like we can then infer the family tree of this 90 000 year old individual and say she was the daughter of an anatol mother and a Denise even father wow so that's that's an astounding Discovery to stumbled upon this first generation blending of these two lineages but but Becky when you heard of this work I mean what was your response because I gather you've been thinking the necessity of bringing hybridization into the story for a long time were you like thrilled by this or like yeah I already know that what's so surprising about that um I wasn't surprised I was uh happy that that uh F1 hybrid had finally been found it didn't it didn't Shock Me In in any way I have to confess but you know part of the reason it didn't shock me is I think we've been seeing over the last decade of these genetic studies is that um hybrids aren't all that uncommon right I think the issue was would you ever find a first generation one which hadn't been found before and eventually you're going to find a first generation one um yeah so I guess it wasn't a huge shock um but if I can speak a little bit to this this hybrids aren't all that uncommon thing um I think one of the things that really that that stands out for me in this work is that and I think it's amazing it's wonderful to find these genetic studies but you know as Tom was saying you know we don't really know very much about what they look like so we don't know much of anything in terms of morphology we don't know if some other fossils that we don't have genetic evidence for might actually be Dennis events so Sheila Becky made reference to the fact that she's not a great fan of this biological classification of of species and uh I don't want to put words in Becky's map I suspect part of that comes from when I was in in 10th grade in Mrs Goldberg's biology class we learned that species were those groups that could not produce fertile offspring right and yet we seem to be talking about Denise event neanderthals coming together and and presumably yielding hybrids that can actually reproduce so so is it useful to talk about these two lineages as distinct species and and moreover if they're all living together in this in this communal cave how should we think about that part of the evolutionary past the study of living human variation has kind of gone through a healthy post-racial Reckoning and yet we're still talking about ancient human variation as branches on trees so um at a minimum I think it it prevents us from getting at really you know meaningful answers about evolution and at its worst I think it's it can be dangerous because the um the people who live in these regions um I think are kind of getting treated as branches on a tree and that can have really you know really problematic implications yep can I jump in yeah please Becky when we when these scenarios are painted that break break human ancestors into different groups one of the things that's been done is that you know one group is adaptively superior to the other or you know better in some way so they've adapted in different ways and and one is more advanced in terms of their intellect more advanced in terms of their tools more advances all of these things and I think that's what Sheila's I'm speaking to in terms of reifying these very problematic ideas that we've eliminated in living people but we continue to perpetuate when we're looking at the fossil record and why that's really important is to me the fact that you have or all the time we you know we look at something look you get oh hybridization oh there's another one hybridization oh another one in human evolution actually it tells me something behaviorally it tells me that these groups of people were coming together often and that their behavior wasn't really all that different you know and their culture wasn't really all that different because if it had been I promise you we wouldn't be seeing this sort of frequency of individuals who have the who have these signatures of hybridization in the genome Tom I'd like to hear your views on this too do you view the Denise events as a a different lineage or what the right word is a different group um should we jettison the idea of thinking of them as different species Tom what's your take on that yeah I think it it's a really complicated uh area and I I get I get uh uncomfortable talking about it to an extent so um I think the reason that we have these difficulties is that in terms of evolutionary time we don't have to go back millions of years to find the last common ancestor of these groups it's comparatively recent right I mean if you're looking at neanderthals and Homo sapiens let's say you know you're looking about half a million years and for for Denise Evans and the anatols comparatively brief at times and that means that enough time and separation geographical separation hasn't accrued hasn't gone by that when they meet once more from their geological geographical separation that they aren't able to uh produce offspring that then can they can can they gone themselves to have a healthy Offspring so um of course we're going to have problems discussing this species concept and it doesn't work as as has been pointed out in this particular context labels are important um though and I think I still think that when we're talking about um let's say groups of Neanderthals and groups of denisimons that these values have these labels have value because we can see physical differences between these groups we can see the morphology um is very clearly uh different and I think for that reason they're important to maintain and to keep but I agree with everyone that the species um the the species discussion is uh is extremely and exceedingly complex um but to give you an example well you know when we're looking at Denise Evans and Neanderthals we know from the from the from the archaeological evidence in the fossil record and the genetic evidence that these are groups that are largely speaking in different parts of the continent of Eurasia they're in the West in the case of Neanderthals they're predominantly in the east in the case of um of denisovans and when Denise Evans and nettles met on occasion they for sure had viable Offspring um whereas in the east in the west I should say in the Neanderthal um uh dominated part of of Eurasia we don't get any Denise even DNA in that part of the world at all and so there's a degree of separation and so using the the available data I know there's a a portrait that's been painted kind of artist rendition of what this lineage might look like we can show it up on the screen how accurate of an image do you guys consider this to be and and and how useful is it or is it not useful to sort of conjecture what things look like in the past based upon this very important but minimal data yeah so this is not based on the DNA code itself and it's based on inferences of what one would expect to see when you get a specific type of regulation on the DNA versus another um I think it's very useful it is in some ways inferences that would have to be validated against the fossil record and against genetic genetic data but I think it's very useful because it gives predictions as to what denisovans looked like and then we can take the fossil record that we know of and possibly new fossils that we found and try to see okay does that fit into our expectations or whether Denise of and what would look like and it's certainly better than what we had so far which was three teeth a piece of a bone and then half a jaw so anything more than that is more than welcome I mean if we're walking around at the appropriate moment in the place to see and we bump into the nearest Denise event is is is that the image that you imagine of the person that will encounter that they'll look like that I think that that is a fun inference but it's impossible not to recognize that that's filtered through um so many of our present-day cultural lenses about what um people look like and so you know if you if you look at the um about you know the very popular image of like an ape and then a stooped man and then a you know an Iraq human um they're always brown skinned and dark-haired until the last person right and so um so you know there's obviously um interesting science that's being brought to bear into these reconstructions but ultimately reconstructions are um are interpretive do any of you have any any even just a a gut guess about whether language use was part of the behavioral repertoire of Neanderthals anyone want to go on a limb online I'll make a guess yeah please I'll make a guess thank you from reading so much if they couldn't communicate um it just doesn't make sense um and and speaking to what Tom was just saying I mean we also know that Gene lineages don't you know diverge the way humans do and Gene lineages don't mean species necessarily so we have to be kind of careful in that in that space as well I guess I'm I'm a little bit uncomfortable um with the way that the conversation has shifted here and and I'll tell you why it's because it's it's sort of going back into this idea that we can find relatively pure groups and the other is messy kind of in the middle so like the Western neanderthals for example we know we call them classic neanderthals there's no evidence for interbreeding they do look quite distinctly different but that's not the case when we get you know into other parts of the world where neanderthals and and um other human groups were overlapping with each other so I I think I'm echoing Sheila's previous concern that we don't go back to this idea and it's something we do it's something we it's something we've been doing forever go back to this idea of of just seeking out differences between these groups rather than trying to understand all of them in terms of this incredible variation because that's what's happening you're getting gene flow between these different groups and what it's doing is it's contributing new variation to who we are today it's if you will it's the fuel of evolution right it is allowing us to adapt and to move into migrate into lots of different spaces but it all still resides in us today and so if nothing else it's it's actually um it's a it's a positive force but I think if you think of a scenario where we have um much much lower population density than we have today right really very very low population density you're going to have groups of these ancestors um spread across this which means just by definition you know we're social animals so we live in in Pockets within that um because they're so dispersed on the landscape and because people migrate to get new resources and for other reasons you're going to have differences that are due to chance you're going to have to have differences that are due to Adaptive differences within groups because they've settled in different regions of the world um and then they're going to come together every so often and they're going to exchange genes and that's the pattern that we're seeing it's actually reflecting a low density and we haven't talked much about genetic drift and chance effects but it's reflecting a low density of people on the landscape gives them opportunities to diversify but that doesn't necessarily mean that they're meaningfully different right in in a meaningful way it just means that they're different because we are too at the end of the day so in thinking about the various human lineages Vivian should we envision that the Neanderthals went extinct is that the right way of thinking about it so I think that people talked about neanderthals not so much about the new students we didn't know about but about neanderthals going extinct because the type of stone tools that they make or they made at some point disappears from the fossil record and at some point the skeletons that can be attributed to them also you just don't find them anymore and so from this came the idea that they they completely went extinct now one of the actually first insights that came out of sequencing a neanderthal genome was the fact that there is still Neanderthal DNA in people living today so anyone living today that is not of sub-Saharan African ancestry carries between one to maybe three percent of their genome coming from Neanderthals and so if you think about this like that then you know perhaps the NFL didn't go extinct in a way they still live within us so also for sequencing uh the denisovan genome and then comparing that genome to people living today we know that there's DNA of Denise events in present-day populations so if you go in Oceania in some parts of Papa for example you have people living today that have up to six percent of the genome coming from Denise events that's quite a lot um and we do find also denisov and DNA in in other parts of Asia and so again in some ways they just didn't disappear they still parts of them live in us and still affect our genomes today and I heard and I don't know you can correct me if if this is just you know one of those urban legends that you find on Tick Tock or Twitter but that that the way we in the modern era right now respond say to various viruses like covid even is potentially impact did by some of the Neanderthal DNA is that is that real is that nonsense yes it is real it is real and it's actually I think one of the interesting aspects of looking at Neanderthal DNA and a Denise of an DNA is that we can still think how does it impact our our own health in our own world today and covet is a great example um that sort of came out of this unfortunate pandemic that hit us all um is that by comparing genetic variants that affect the susceptibility to this to develop uh Covenant and severe covid-19 symptoms it was found that there is a specific genetic variant on chromosome 3 where people living today if they have the Neanderthal type of this variant there are more likely to develop severe symptoms of covid-19 if they catch the virus and so as I said this means that the neonatal DNA in us or in some of us still affects us today and quite interestingly sort of a few months later with more analyzes coming up than another variant in another part of a genome was found and this time if you have the Neanderthal DNA it's actually protecting yuke from coven 19. so depending on bit on the lottery of genetics you know it may be good and it may be bad to have Neanderthal DNA so so Tom Becky you know with all this very recent work that's suggesting these interesting New Perspectives coming from the fines uh in China what what do you think the the Gestalt could be going forward in terms of thinking about the structure of our evolutionary past is it is it more a give and take across the world do we need to get rid of this old image as Sheila was saying where we're kind of imagining things flowing in One Direction not the other yeah I mean I do I I I think that you know The Narrative view that was introduced in the beginning the idea that you have one group of humans those that one group of humans um it becomes you know more capable becomes uh conquerors becomes better adapted to Being Human has all sorts of genetic changes that make them human leaves the continent conquers conquers conquers conquers conquers right and takes over the world that was essentially the Out of Africa narrative such as it was and that is that's pretty much demolished right it's not a thing so I guess the question that that we have going forward is is the noon what does this new narrative look like in detail so I think we're slowly it's like a slow progress moving away from this very um simplistic very replacement very unidirectional model and I suspect I mean if I'm going to kind of put myself out there um that as we get more and more and more information and goodness it wouldn't it be nice to get more um genetic information from Africa as well um that's deeper in time that we're going to get exactly this a much more complicated picture of um movement that it's going to be much more I would say evenly distributed uh then the picture that we're getting now but you know we'll kind of have to see we'll kind of have to see where this where this takes us so Becca you've already emphasized your view that the older canonical Out of Africa approach has been in your words demolished and is it more just there's a blending and because of that some new hybrid emerges and the whole notion of going extinct may be itself a too simplistic way of thinking about things that's a difficult question to answer you know I I I'm going to say something first that I've been wanting to say and that is that um variation produces Evolution right Evolution produces variation this braided stream if you will of people has resulted in increasing variation so the the species that we have today has a lot more variation in it genetically than it would have had if some of those things hadn't happened bits and pieces were picked up through and kept and some things were lost and some things were kept and they're put together in New in different ways but we're very variable and that gives us um resilience right resilience in the face of change resilience in the face of new environments and so something goes extinct and that's not really what we're seeing because it doesn't none of this fully goes away in the human record it's just producing this increased variation that has resulted in in who we are today and then to speak to something else that you mentioned um you know and you were talking about these new fossils and new fossils being found in different parts of the world and how exciting that is and it's adding to our knowledge of the evolution of our lineage and of humans generally where people are looking matters who's doing the looking matters who has the money to do the looking matters um who's shaping the choices and the narratives matters and we've had a long history certainly in perioanthropology a very specific groups of people out there and asking the questions and doing it in very specific kinds of ways and often marginalizing others or simply not involving them at all and so for me that's kind of the most exciting um path that we have going forward is this ability to start to forge real relationships with people on the ground and start to have conversations that that fit the global movement that we're having about you know why are we so interesting why are we so diverse and you know how can we learn more about um how we became these sort of complex diverse humans that we are today so jump on off in that one final question I'm often asked the question about life in other worlds I suspect you all are as well and and my view has always been that with the great number of planets and the great number of stars out there I think most of us have an intuition that life has a good chance of being out there somewhere in the cosmos that often I follow that by saying but life is one thing an intelligent life is something completely different because intelligent life when you look at Planet Earth my previous View was there's like one single example of it and by intelligent I mean intelligence the level where you can build a radio telescope you can build a rocket ship should we view that intelligence itself has arisen many times on this planet in many different places and therefore would that perhaps suggest that intelligence is more of a natural outgrowth of The evolutionary process as opposed to some singular event that bequeath to the world called Homo sapiens final words on that thought when we start with Tom yeah um that's a really uh that's a really good question and I think the answer's got to be yes because um if we look again harking back to um some of our um some of the wider Human family the most well-known on neanderthals um so you know we we we we lose neanderthals we think somewhere around 40 000 years ago so between 40 000 years ago and today that's a long tract of time neanderthals no longer had the um had the possibilities of going through the climatic and environmental changes that we did undergoing the selection pressures that we did um you know responding to to various changes and and adaptation uh that that we did and so uh running the tape again I don't have too much doubt that neanderthals could have got onto a very similar type of evolutionary trajectory that we did Denise Evans we know virtually nothing about in terms of their archeology G but we have as I say we have this evidence that they were probably quite capable too it's still emerging and still controversial but if we accept um that Denise Evans made it to um Island Southeast Asia or east of Wallace's line they must have had a degree of technology to be able to do that you can't just swim across those gaps you have to have some kind of Maritime based technology we know that hominins that were much earlier than that and older than that did too you know the ancestors of homophoresiensis on Flores and Homo luzonensis on on the Philippines and so yes I think it's it seems to me that uh it's more than likely that this type of ability and this type of intelligence that we formally only saw in see in us could have Arisen more than once yes Sheila thoughts on intelligence and number of times it's Arisen on planet Earth so I mean intelligence is a cultural construct um and but I get what you mean right you know the the idea that we are um you know we are the only species on Earth that turns the microscope on ourselves right and asks our own questions about ourselves um but I think it's uh we we cannot possibly Trace that back in the um false and archaeological record without some of our own cultural biases and so um you know historically we talk about behavioral modernity in these very um in these very Western European terms and so we look for art and we look for adornment and we look for you know and and we and those are what colonialists look for when they were trying to say that this civilization was you know civilized or not and so you know to Tom's point there are other ways to express extremely complex and Abstract capabilities Maritime technology and um all of the implications of of climatology you know understanding astronomy and um and climatology all the things that are required for for doing um any sort of Maritime activities then um then I think that we shouldn't assume that it start it it is um the Hallmark of homo sapiens because there's just so much evidence of these skill sets that um that we would consider abstract thinking that are um present simply by the presence of a fossil record in Indonesia at you know one million years ago Vivion the uh wide birth of Intelligence on planet Earth yeah so I think it's also important to think about the fact that we're not the only intelligent species out there right we're not the only ones who make tools we're not the only ones who are capable of changing our environment in order to adapt to it I think we are shifting from a way that we used to look at neanderthals researchers looked or used to do look at neanderthals as these sort of incapable a bit stupid uh human beings that sort of were too stupid to survive and we certainly I think most of archaeologists today and and people studying the past with the degree that this is no longer what we think and we think there was a lot of exchanges of culture and exchanges not only of genes uh between these populations and that it is not only the intelligence that sort of drove us to to still be around today Becky you've got the final word intelligence on Earth how widespread it may have Arisen and if you're willing intelligence through the cosmos all I can think of is the octopus yeah oh yeah I mean no I mean really right yeah the the problem with defining intelligence and this is a classic classic thing in primatology is that you know for for so long we Define intelligence through the lens of of ourselves and through the lens of whoever's whoever is making those definitions is filtering okay so can we measure them by us can we measure can a can a chimpanzee um Flint nap tools that are just like us okay yeah they can but can they do it on their own would they come up with the idea right so we're always filtering these things through our understanding of our type of intelligence so I think that's one point but more broadly to your to your question here um you know yes all of these hominins they've they've been um constructing their niches for hundreds of thousands millions of years and moving into different places so they all had a very high level of intelligence and I would definitely um absolutely I'm sure there are other intelligent forms of life do they look like us no probably not and different planets are they um intelligent in ways that we can't understand it all because we crazy humans like to filter things through our way of thinking about intelligence in no other way um yeah they're probably really different and we wouldn't maybe even be able to recognize the intelligence when we saw it well thank you all for this fascinating conversation on on the present potentially the future of our evolutionary past so thank you all for joining us [Music] thank you [Music] thank you

Channel: World Science Festival

Views: 114,499

Keywords: Brian Greene, Brave New Prehistoric World, PREHISTORIC PLANET, paleontology, Anthropology, Neanderthal, biological anthropologists, Paleolithic archaeologists, earth scientists and geneticists, Rebecca Ackermann Thomas Higham Sheela Athreya Viviane Slon, modern humans, hominization, petrified skeletal remains, bone fragments, footprints, stone tools, artifacts, evolution, New York City, World, Science, Festival

Id: 5Iy5mt7F_N4

Length: 67min 31sec (4051 seconds)

Published: Thu May 04 2023