The evolving story of human evolution | Melanie Chang | TEDxVictoria

so in my civilian life when I'm doing normal things like taking my kid playdates or something and I introduced myself to people and I tell them what I do I usually get one of two responses either a blank stare or something along the lines of cool I love dinosaurs now I did want to study dinosaurs when I was five like I think most five-year-olds do but I I don't actually study dinosaurs I hate to disappoint people I actually study human evolution because I kind of never really outgrew a lot of the impulses that made me want to study dinosaurs in the first place but what I ended up studying with Neanderthals so you can see one here and you can see I'm really happy about it Neanderthals are an archaic human species that are probably the only archaic human species that almost everyone in this room knows by name now the timeline of human evolution is about eight million years long but Neanderthals only went extinct about 30,000 years ago and meanwhile our species is about two hundred thousand years old so what that means is that we were kind of like the star-crossed lovers of human evolution we have archaeological evidence that indicates that we overlapped enough in both time and space that we could have met face to face and if you follow the science news then you know that we now have genetic evidence that we definitely did meet face to face and in a number of other ways so today though modern humans are a very lonely species we're the only species of our kind left on the planet and I think that's part of the reason why so many of us are obsessed with things like sasquatches and yetis because if there are really hairy bipedal ape still running around out there somewhere in the woods I know everyone like sasquatches in the Pacific Northwest then it would mean that we were not really alone on this planet and I think that that's part of the reason why Neanderthals seem so endlessly fascinating we know that humans and dinosaurs never actually coexisted many cartoons now standing but we also know that our ancestors knew Neanderthals and this brings to mind all sorts of tantalizing questions like when our ancestors met Neanderthals and they looked into their eyes what did they see did they see another kind of human were we enough alike for them to think of them as other humans or were these Ice Age encounters more like really early instances of primatology now fact that paleoanthropologists even ask questions like this and we do ask questions like this only we usually try to sound a little bit more scientific when we do it makes the study of human evolution very different from the study of the evolution of pretty much any other kind of organism I mean you know as awesome as charismatic as everyone thinks that saber-tooth Tigers more because everyone thinks that right because they were awesome but knowing we don't usually go around thinking about their emotional lives or wondering what they were like but in contrast paleoanthropologists are tasked with the mission of reconstructing our evolutionary past and events in it in as much detail as possible and that's a pretty tall order when the data that we have to work with are things like stones and bones and the fragmented decayed genetic remains that we can extract from those bones now we are also at a relative disadvantage compared to scientists in many other fields because we are generally unable to generate data in the lab we can't put a Neanderthal in a steel cage or the modern human to see if they fight out to the death or if one of them asks together went out on a date the way that some scientists can do things like generating chemical reactions in the lab or growing bacteria in Petri dishes so instead what we do is we collect data through fieldwork and fieldwork is an incomplete and rather slow sampling process although it's also enjoyable because it involves stuff like foreign travel and camping and drinking lots of box wine around the fire at night and field practice can last years by the way but despite the fact that we do all this work at the end of the day we know that the amount of data that we have is only a painfully small fraction of the total story of our evolutionary history our data set remains very very incomplete for those of you who are not familiar with American politics I think you kind of get forced to be here this is former US Secretary of State Donald Rumsfeld and frequent unintentional prose poet Donald Rumsfeld he once famously distinguished between known knowns unknown note sorry known unknowns and unknown unknowns the last of which represent those things that we don't know we don't know and what I know is that there is actually a lot of debate over whether this quote is inane are profound I actually find it kind of profound I might be kind of biased by what I do but the thing is that human evolutionary studies are especially vulnerable to Revelation or perturbations due to the discovery of previously unknown unknowns now Neanderthals were the first fossil humans known they were discovered in the nineteenth century and at that time there were signs like these rumblings and murmurings about the possibility that species could evolve and change over time but for the most part everyone thought that the world was young and that every living thing in the world had been specially created supernaturally exactly as it was now there was a very popular estimate of the date of creation that was established in the 17th century that had the earth being created on 6 p.m. October 22nd 4004 BC and this was the date that everybody went with for hundreds of years it's still printed in some editions of the Bible but what this meant was that when the first Neanderthals were discovered like my friend from Gibraltar here who was discovered in 1848 they couldn't be interpreted as anything other than kind of robust but otherwise garden-variety modern humans but then by the time a fossil was discovered in the Germany's Neander Valley which translates to Neanderthal in Germany because tall means valley the publication of Charles Darwin's On the Origin of Species was just around the corner it was published in 1859 and he went a long way towards convincing the biological establishment that biological evolution actually had occurred although the idea of humans evolving still made a lot of people really nervous now many Western scientists of the I'm believed that they already believe that modern human societies could be ranked in this sort of ascending scale of complexity or an Enlightenment from savagery to barbarism to civilization you can guess who they put in all of these categories but if you kind of overlay in evolutionary context on top of this then you can think of you can think of Neanderthals as being sort of the uber savages you know more primitive than any modern society even the most backwards according to current thinking and so therefore more appropriately compared to non-human Apes like gorillas for example so here we have a scientifically endorsed reconstruction that was printed in the Illustrated London News in 1909 based on a monograph by a French anthropologist named Marcel ampoule and he he endorsed this Reconstructor and he felt like this really expressed what he felt about the Neanderthal fossil that he was describing and so this probably looks kind of familiar to you he's hairy he's dark he's not completely upright he's got the savage expression on his face he's got a club in one hand this is essentially the scientific origin of the club wielding knuckle-dragging caveman stereotype that is still with us today these questions about how human we thought the Neanderthals were and what it might have been like to be to meet them are kind of fundamental questions in evolutionary biology in human evolutionary studies and they have been ever since there have been human evolutionary studies but at the time that the Neanderthals were discovered there was no real idea that the eventual recovery of Neanderthal DNA would ever happen now Charles Darwin didn't know anything about genetics much less the structure of DNA and then 150 years later things changed we have technological advances that allow us to actually extract DNA from fossils and the first Neanderthal DNA studies which started being published in 1997 we're kind of a bombshell in evolutionary studies they seemed to definitively exclude Neanderthals from modern human ancestry for one thing the samples that they were getting from the Neanderthals were far too different from what they were seeing in modern human populations to consider them to be members of our own species and on top of that so-called molecular clock studies seem to indicate that the date of divergence between us and the end or tall's was far too early for them to be counted among our ancestors and so the genetic data with its orderly code here in perceived objectivity was held in strong contrast to the ambiguity and difficulty of interpretation of fossil data and so together that was enough to convince many researchers that Neanderthals could not possibly be our ancestors and put to rest any notions that we ever would have interbred with Neanderthals but those studies were all based on a kind of DNA called mitochondrial DNA and that is a separate genome that lives in all of your cells that is distinct from the individual or the nuclear genome which is that genome or that stretch of DNA that essentially makes you you it's like the blueprint for you and so you may wonder why scientists were looking at the mitochondrial DNA in the first place and not at the nuclear DNA and the reason is that it was what they had to work with at the time the mitochondrial DNA like all mole DNA like all organic molecules will decay over time and mitochondrial DNA is far more likely to survive in fossil samples simply because it is far more abundant to begin with and on top of that ancient DNA samples are commonly contaminated by DNA from things like bacteria and fungi and the DNA of modern researchers who have handled the fossils like yours truly so this further obscures the signal that's already being obscured of the nuclear DNA but and you know there was but coming there too a few years ago and by within the last few years I mean like within the past two or three years there have been these major technological advances that have allowed us to actually do something that 20 or even 10 years ago a lot of us would have said was completely impossible to do and so last year researchers in Germany published and assembled a complete Neanderthal nuclear genome using the fragmented and decayed samples of DNA that they extracted from this fossil toe bone back here now this is an achievement roughly the equivalent doing something like reconstructing all of Tolstoy war and peace based on the stuff that you got out of the bin of a crosscut shredder except the guy who shredded it threw out every other page before he threw it in there and then threw in several dozen copies of the IKEA catalog and SkyMall before shredding the whole thing except what the researchers had to work with was even worse because war and peace is only five hundred ninety thousand words long and human genome is three billion base pairs long so the fact that they were able to assemble this genome was astonishing enough but then what they found when they compared it to modern human genomes was that many modern humans actually carry between one and four percent Neanderthal DNA this is exceedingly strong evidence that we did in fact mate with Neanderthals and that kind of makes it difficult to kick them out of the family not only that but further studies indicate that the ice age was actually a very busy place in terms of archaic modern commingling and that paints a very more complex picture of all of our past relationships than we previously thought that one science website summed up the slee so I'm used to these kinds of headlines in my line of work but anyway you may wonder exactly how it is that one kind of DNA evidence could seemingly completely contradict on other kind of DNA evidence and there are a lot of answers to that question but one of the most simple is that when we use different characteristics to reconstruct evolutionary history sometimes different characteristics give us different stories so for example we can take digit number humans have five digits on each appendage we have five fingers and five toes you can't see mine but you have to take my word for it get those also have five toes on each foot but horses only have one so going by digit number you would think that perhaps Donald Rumsfeld is more closely related to a gecko than to a horse however on the basis of the preponderance of information which indicates that you know all of those things that make mammals mammals we know that Donald Rumsfeld is actually not more closely related to reptiles and so here in Neanderthal DNA we have the case where new data basically changed a misinterpretation there were originally made in the context of incomplete data and that's the way that science is supposed to work now I know that many people find the shifting nature of the human evolutionary story very unsatisfying science isn't supposed to change it's supposed to be about hard facts it's supposed to be out truth and the truth is supposed to remain the same but I think this also may explain why public opinion polls say things like that four out of five Americans believe that science is valuable and they're really interested in new scientific discoveries but if you put them on the spot about specific discoveries and findings they often resist or have difficulty believing them like 42% of Americans don't believe in evolution or 54% of Americans believe in a supernatural explanation for the universe fifty-one percent don't think there was ever a big bang I'm not even going to get into the stats on vaccine safety and climate change because that's just depressing but I think that some of the reason why people have such a hard time with this is the part of the way excuse me part of the is because of the uncertainty that's inherent the way that science works and this is a problem for a lot of people because people are emotionally invested in Neanderthals when we ask these sorts of slippery questions about what it means to be human and language and culture and things like that then they really feel like if these answers are uncertain then it leaves us with uncertainty about our own natures you know the news that dinosaurs had feathers probably rocked the world of a lot of aspiring dinosaur paleontologists it certainly did mine because when you think of t-rex as a giant chicken things are just not really the same after that but you don't see emotional reactions like this one you know like feathered dinosaurs don't make you start rethinking man's inhumanity to man so the fact is a lot of the things that we want to know about Neanderthals are things that we might very well never know like what would happen if I sat down next to this guy the bus stop and asked if I was done with that paper and could I read it a fee was done would he attack me what he asked me out on a date I don't know but I have a colleague who answers a lot of those kinds of questions with well I don't know get me a time machine and I'll tell you but people don't really want to hear that and even paler anthropologists don't want to hear that we want to know the answers otherwise we wouldn't have gone into this line of work in the first place so instead we keep on working incrementally making progress finding new data hoping that this new data will give us new insights into Neanderthals and sometimes those insights are so new that they change everything that we originally thought about them and this is the way that science is supposed to work I am personally very excited to see what's on the next page of the story thank you

Channel: TEDx Talks

Views: 349,647

Rating: 4.7460017 out of 5

Keywords: Canada, TEDxTalks, Archeaology, Science (hard), ted talks, tedx, Genetics, ted x, English, tedx talk, tedx talks, ted talk, ted

Id: WLXPi0Jha5o

Length: 16min 26sec (986 seconds)

Published: Mon Dec 22 2014