WN@TL - How New Discoveries of Homo naledi are Changing Human Origins

welcome everyone to Winston at the lab I'm Thomson and I work here at the uw-madison biotechnology Center I also work for UW extension Cooperative Extension and on behalf of those folks and our other co-organizers Wisconsin Public Television Wisconsin alumni associations and the uw-madison science Alliance thanks again for coming to Wednesday night at the lab we do this every Wednesday night fifty times a year tonight's my great pleasure to welcome back to Wednesday night lab John Hawkes professor of anthropology here at uw-madison he was born in Norton Kansas and graduated from Norton community high school and he went to Kay to Kansas State University where he studied English French and until pallavi then he went to Michigan got his PhD at anthropology did a postdoc at the University of Utah and in came UW Madison in 2002 that's a testimony to what a extraordinary presenter John is and what a great story he has to tell the backer your name is sandy what's your friend's name you yeah say good Paul Paul just told me this is the first time he's been in a lecture hall - university of wisconsin-madison since 1968 and I think that's a great testimony to it I was here last night if there's a better storyteller let me know if there's better stories let me know than what John Hawkes that's going to share with this I think in future years people will look back at this recording and think man I wish I was there to see it in person you are all lucky enough to see and hear John Hawkes tell us about his latest update on Homo Naledi please join me in welcoming John Hawkes thank you Tom thank you everyone for coming out I've been in the u.s. now for four days and and a week ago at this time I was in the field working underground with homo Naledi and I will tell you that we have some remarkable new findings from the cave system a lot of you have come out for previous talks that I've sort of presented our initial findings on home on the letti our discoveries in 2013 our publications in 2015 we've had some some incredible things but we've also had some incredible mysteries that have arisen how did all these bones get into this remote cave chamber what are they doing there when did home on the letti live how was it connected to our species these are the things that we've been investigating for the last four years now and I can tell you that we can answer some of those questions and many of the questions have become more intricate and fascinating for us I know that some of you haven't heard all of this story before and so I have to present sort of how the cave was found and where I come into the story and what the excavation was and why this was news in the first place and I'll do that in the first part of tonight's lecture then I'll talk about the publications that we had earlier this year where we uncovered a second cave chamber in the rising star cave the Lacetti chamber a second cave chamber with more remains of home on the lady with a wonderfully complete skeleton that we've named naio and here's Nao's skull here on the on the first slide and at the same time we determined the age of the fossils and the age surprised many people in the world who did not expect them to be the age that they are so it was a wonderful discovery but in the last third of the lecture I want to focus on what we are doing now and what our most recent field excavation has uncovered this is the newest stuff this is stuff that I didn't know last week at this time right so I we'll give it to you unfiltered and some of it may be stuff for the history books and some of it I may change my mind about two weeks from now but it will certainly give you the freshest take on it and you guys are the first people outside of South Africa to know any of this except for the people at the University of Alabama because Lee beat me at this for one day one day so let me it's a wonderful privilege I say this whenever I present on this stuff that we have the involvement of National Geographic in the project and also of the University of Wisconsin who both have enabled us to film a lot of the original research as it happened and we have footage from the initial discovery of the fossils in 2013 we have footage through the analysis of the fossils through the first field expedition through this field expedition I'll be showing you video later that I took just this month and that our team took underground this month so so it's wonderful because I get to show you some of this stuff and allow people to tell their own story in their own words and one of the most important parts of that is the discovery of the fossils so to show you here Steven Tucker who was the first person to enter the denill Eddy chamber kevin has always been great having you once you answer that question of what's around the next corner that's not always a question tonight it's mostly fueled by curiosity but as you get into caving more and more the scientific side of it comes into it you want to know how did these places form what happened here millions of years ago what happened here billions of years ago basically creates a fascination of the small environment in my wildest dreams I would never have thought that caving would take me to what's happening here you can almost call this a bit of an ass so my Kevin Bunyan burek we were up exploring this cave on a Friday night we'd gone to a very remote section of the cave part that I've never been in before and in that sectional we stumbled upon fossils yeah at first we didn't exactly know what fossils yet we started looking around a bit more and so we found a mandible and that was we knew this was probably hominid that was America we got excited about it and since this discovery it's crazy what's happening yet so that was the discovery of the fossils that occurred September 13 2013 so that's four years ago we celebrated the fourth anniversary last month Steve at the time was studying to be an accountant and Rick was unemployed and basically a super super clever guy who loved cave on the weekends and these two guys were exploring for fossils they were working with my friend Lee Berger who is a National Geographic explorer-in-residence also professor at the University of Witwatersrand Lee is famous for having discovered Australopithecus sediba in 2008 and the story of sediba goes that his son found the fossil the story of Naledi goes that these cavers found the fossil they were looking for fossils and in this cave which is less than 800 meters away from one of the most famous fossil sites in the world Swart Cron's less than one and a half kilometers from sterk fontaine the largest fossil hominid assemblage in africa at the time this area that within two kilometers are five famous hominin fossil sites no one had ever located any fossils in this cave they're there and these guys found on that first trip not only the dental Eddie chamber but also they went through a second chamber the Lacetti chamber and I'll show you that chamber later they didn't wreck nice at the time when it was only after we began working in the dental Ettie chamber did they realize hey we've seen something else like this maybe you guys would be interested Steven no longer is an accountant he's now is a full-time Explorer for our exploration team as is Rick and we have an exploration team that's in the field every day professional explorers and they are at this point some of the most experienced cave explorers in the world Steven however can be trusted to review a budget the dim Eleni chamber is in an excruciatingly ly difficult to access part of the cave system the entrance that we use the closest entrance to this in order to reach the dental Eddy chamber you have to go through some very serious vertical climbs this is about 40 meters underground this is about a 30 meter climb down to the Superman's crawl you the Superman's crawl is a narrow squeeze with a height of about 10 and a half inches that's called this and I'll show you footage of people going through it in a while it's called this because if you have any size at all you have to go one arm first and squeeze through it this way it's all horizontal but more seriously after climbing a very rugged sort of rock fall called the Dragons back you can only access this chamber through a vertical passage that is a width at a minimum of seven and a half inches and a height of 12 meters so it's a 40-foot vertical climb that's the only way in or out I cannot enter this chamber Lee can't enter this chamber in fact only a very committed group of people with the right skills and talents can enter this chamber leave at initially upon the discovery of this didn't know how he was going to get people to recover these fossils he put out an ad on Facebook which later became famous I need people with excavation paleontological skills who can pitch up here next month for no pay and you must be skinny and not claustrophobic he recruited these incredible six cavers explorers archaeologists all of them masters PhD students in archaeology including Illya Goethe from the University of Wisconsin but others from the US Canada Australia marina Elliott you're gonna see a lot tonight she is now a full time head of the exploration team at the University of Witwatersrand just this last month we had Becca ellen hannah all-out at with marina for our last field expedition so the archaeologists who were initially involved remain committed with us Rick hunter who you saw in the video is married now to Lindsey Hunter don't giggle this is the sort of thing that camp people like me are supposed to prevent from happening I can't I'm not a good chaperone sorry I've got three teenage daughters I have my priorities this is the opening to the shoot and I want to show you some video we have on this trip managed to get some extraordinary video of some of these passageways through the cave that we haven't been able to get video in before now we can use a Steadicam setup with the GoPro that with the right lighting situation can actually see into some of these chambers so I'm going to show you what it's like to go down this chute this is the first time I've shown this video anywhere so we'll see if it comes out alright this is Becca Becca can she's just about four foot ten and she can fit into things that no one else on the team can and you're gonna see her squeeze into this crack that none of the rest of the team knew was there and [Music] we're gonna have a camera switch now and because marina of this next section of the shoot and once she gets up to the top here which is just another second we're gonna see Ellen coming up the rest of the way out of the shoots and you'll see part of that this part of the cave is actually a dotted line you saw that the the map that I showed you earlier had its laser scan data through the entire cave we have three dimensional point cloud data from lasers and this is the one part of the cave that we can't actually get the laser into this is what our team goes through every day to get down to where the fossils are well the most skilled members of the team can do this climb in about three or four minutes most people take five to ten depends on how much gear you have to also haul up to get from the cave entrance to this point to do the descent or from here to the cave entrance is about 20 minutes to 25 minutes through the cave system now this distance through the cave is about 170 meters so if you guys can imagine moving right something like the length of this building right through the biotech Center in the genetics building right this 170 meters more or less imagine taking a half an hour to do that and you get some idea of how difficult it is to move through these places and these people are all now professionals I'm talking about people who cave now for a living who are doing it in that time period people without this sorts of skills you're talking about much longer well the story of our 2013 expedition we all assembled in November of 2013 our team went underground we were there for 21 days underground the team in that time span recovered more than 1500 fossil specimens almost every single one of them was a hominin fossil specimen and it was immediately the largest fossil hominid assemblage ever discovered in Africa it is the second largest fossil hominid assemblage in the world it's an amazing amazing discovery and and nobody had ever seen anything like it represents every part of the skeleton multiple times in most cases we have the remains of at least 15 different individuals in this chamber what a lot of people didn't appreciate at the time was that aside from a surface collection you saw their bones on the surface and we collected from the surface of the entire chamber there were around 300 bones and bone pieces from the surface of the chamber the rest of those bones all come from an excavation area that is less than 1 meter square it's Beverly it's about 80 centimeters on a side and the depth of deposit with these fossil hominids is around 15 to 20 centimeters so this is a bone bed that is totally composed of hominin bone under the hominin bone is sterile sediment down at least 50 centimeters at the base of that sterile sediment in the area that we dug we found a single tooth of a baboon we don't know what that relates to but we know quite a lot about its provenience right now because we were able to estimate the date of this and the date of the fossil hominids so we know quite a lot about these at the time this discovery was unprecedented and it was up to us to figure out how to study it we recruited a team of specialists who had been involved in some work in South Africa before people had been involved in the description of Australopithecus sediba and we recruited a team of 35 early career scientists to join us in describing these fossils for the first time that workshop occurred in May of 2014 we did our work we had different anatomical specialists it was a tremendous tremendous experience experts coming in who had done their dissertations on the fir tree the vertebral column people have done their dissertations on the lower limb my students ax Rock Morton who had finished here was an anatomy professor at Lincoln Memorial University in Tennessee had done his dissertation on the foot and we had all these specialists come and describe every element of this hominin and in the course of that discovered that this represents a previously unknown species we compared it to every other kind of fossil hominin that never been discovered we had cast materials or the originals in many cases available to us to inspect and study these are some of them Homo erectus on the left here Australopithecus afarensis that's Lucy's skeleton here and another male offer iNSYS partial skeleton Australopithecus africanus from South Africa Australopithecus sediba represented by two partial skeletons I'm showing you here the partial skeletons of the hominin fossil record before Neanderthals this is what there is and so when we have a collection of fossils that is an array representing multiple multiple individuals it's really really powerful evidence we identified this as a new species previously undiscovered we named it Homo Naledi miletti means star in the local cisu - language which is one of the major languages of South Africa so miletti is very interesting because it's different from other fossil hominids in ways that we did not expect fossil hominids would be now you guys who know something about evolution know that evolution is not a straight line it doesn't occur in the famous illustration of a hunched ape-like thing becoming slowly human-like step by step right it doesn't happen that way our ancestry was complicated there were multiple branches that form a tree and these species are related to each other sometimes in ways that we don't fully understand because they're fragmentary fossils and it's very hard for us to compare you saw the whole skeletons right that was what there was every other piece of thing that we have is a fragment of one kind or another and we have some extraordinary samples of fossil hominin teeth and jaws and in some cases skulls but we don't know a lot about how the rest of the body goes together except from skeletons that actually put those parts together from one individual what we have increasingly discovered over the last 10 to 15 years is that when we have more complete remains skeletons like Naledi like sediba like Homo floresiensis you start to discover that the parts don't always go together in the ways that you might have anticipated you might think that even though things are a tree and they're more complicated than a straight line nonetheless there's a main branch and when things branch off of it they inherit the characters of the main branch and so there's some sort of order to it in fact for the most part there's so much parallel evolution and convergence among the branches of our hominid tree that is very difficult to trace what the main branch might be so when we look at the Leddy's skeleton it puts together characteristics that we didn't expect would go together the most obvious of these is its brain Naledi has a very small brain compared to humans it's about 450 to 600 cubic centimeters in size that's about 1/3 the size of a human brain it's the size of a large orange that small brain is in a skull that has a number of characteristics it's got a torrent an angular thickening of bone here called the angular torus it's got a brow Ridge with a groove behind it called a sulcus it's got a relatively not very high forehead it's got a bar here at the back of the skull called a new coal Taurus it's got no chin but a relatively vertical front to the mandible it's got a flat face these are features that we associate with other species that we attribute to early homo members of our genis but early in the evolution of our genis think fossils that we found that are 2 million years old they're one and a half million years old fossils like Homo erectus and Homo habilis so looking at its features it looks like those early human species it's brain size is too small it's smaller than those early human species so there's a bit of a puzzle my friend John gucci is a tremendously talented paleo artist he's one of the best reconstructors of what fossils may have looked like in life this is his reconstruction of Naledi and I think it's a very good one obviously some aspects like skin tone like the hair pattern have to be speculative in some ways but by studying the distribution of these in human populations other primates John has an educated guess about what they would look like but the overall facial profile and everything is basically this this is a nice portrait of Naledi in this deposit we have the remains of at least 15 different individuals they are of all ages from newborn or what we would call a Perry mate possibly not yet born too old adult and every age group in between this is a series of six different dentition x' that represent individuals and they're all of different ages this is a toddler maybe one and a half to two years old this is a young child of maybe six or seven this is an older child of nine or ten here's an adolescent teenager here's a young adult here's an old adult this is a sample which for the first time we can study development in an entire series of individuals from one place one of the things that we've learned by studying this particular dentition this older child's dentition is that its development is strikingly human-like the human-like detail that said this may be the most telling is that the permanent canine teeth are in those are the the canine teeth they're all the way in and the second molar is not yet erupted this is a very human-like trait our canines erupt early our molars erupt late in chimpanzees and gorillas and other primates and in all earlier hominins that we know about the second molar erupts first and the canine is delayed because the canine is a social signal when you erupt your canines if you're in a primate Society what you're saying is you're ready for a fight because that's what you fight with and that's what you threatened with and delaying the eruption of the canines is a is something that prevents you from getting into fights before you're ready in homo Naledi they have a very human-like developmental profile we can't say what that means socially but it is very interesting because they're so primitive in their brain size you might imagine that their development would be very primitive but actually it's very human-like this is a new discovery that haven't been able to talk about before if we look at other parts of m'ladies skeleton it is actually strikingly human-like its feet for example are your feet if you're a size four women's shoe size anybody's size for any size fours in the room any size fives you're just a little bigger than the lady this this is no Letty's feet this is a very human foot you can see the arch and this foot longitudinally the arch medially media laterally all right this is a human foot it's got a big toe that's actually a big toes lined with the other toes the other tiny toe bones here at MIT are not reconstructed with this because our foot team actually you can't tell this apart you might imagine well you can tell them you know second toe from the fourth toe actually you can't so we don't put them on because we're not confident about the placement but we have all of them the hands of miletti are a mixture of human-like and primitive characteristics this is a complete hand it was found in articulation in the site here it is folded over fingers the thumb here it's a right hand there it is and I'll show you it's got big broad fingertips as humans do which are made for gripping hard objects like stone tools it's got wrist bones that are arranged in a human-like pattern including the crucial difference between the thumb and the first finger which helps to buttress against hard grip forces again tool use but it has tremendously curved finger bones the finger bones are curved in a way that suggests it was grasping onto branches or grasping onto something climbing the lady's shoulder is also really well-suited to climbing its shoulders are canted upwards like this and really well made for reaching overhead so it's got this interesting combination of traits it's lower limb its feet very human-like its skull like an early species of Homo something like Homo erectus Homo habilis but with a smaller brain hands that are really well made for tool making but also well made for climbing and shoulders made for climbing hips that are really widely flared which are very primitive for hominis it's like Lucy's hips it's not like our hips at all it is a weird combination of traits we've never seen it before it has features that we've never seen before in any hominid species so for all those reasons we're really confident this is something new that we hadn't seen before what we and this is John's again reconstruction what miletti would have looked like standing here this is Lucy Australopithecus afarensis and the Turkana boy Homo erectus and you can see that they're really visually different if you were looking at erectus and Naledi from a long ways away from 100 metres away you might think well they're not so different but as you get closer you start to notice that these people don't look like the others they look like us their heads are wrong their standing is sort of an odd posture they walk like humans do but there's something different about them and as you get closer and closer you start to notice those primitive features this is a really different species so after our publication of the species Homo Naledi we began to work in earnest on our second discovery in the rising star cave system the Lacetti chamber this is a layout of the cave as a whole this is our cave map our entrance is here and the din Eleni chamber I've described the pathway to it is over here it's around 100 meters linear distance from the entrance but around 160 meters through the cave to get there in linear distance in a totally different direction is a second chamber the Lacetti chamber the Lacetti chamber is not as difficult to access as the din Eleni chamber nonetheless is difficult there are multiple squeezes between the entrance and the Lacetti chamber I'll show you from the main surface entrance there is a big squeeze or I should say a small squeeze that we've come to called the burger box the reason why is that Lee went to the Lacetti chamber one time and didn't get back out he was stuck at this place and the reason why is you can see it's an uphill climb and actually it's easy to go down through it relatively speaking it's about a 10 and a half it's no it's not ten and a half inches it's about a 9 inch squeeze so Lee can fit through it that way I felt that I couldn't and so I didn't go to that time but you have to get purchased against the ground in order to get back up through it and that takes different muscles and it does going up and people with long legs have a disadvantage and he was stuck there for 45 minutes it's crazy we had to pull him out like Winnie the Pooh out of a stump so Leah's never been to the Lacetti chamber again and I've never been at all there are a number of climbs through this and then a vertical drop into the chamber in this chamber where bones again exposed on the surface during 2014 and 2015 into 2016 our team led by marina Elliott excavated in the Lacetti chamber and recovered the bones of Mayo in addition to at least two other individuals of whom Luna Letty one juvenile one young child and one other adult Mayo Mayo means gift into SWANA which is another one of the local languages Mayo is one of the most incredible - here's marina working in the Lacetti chamber with Ashley Kruger our specialist of 3d all of these images that we have from the caves and the maps and everything involved Ashley creating these from the 3d data before I leave this because it might not be easy for me to get back to it I want to point you to this little area in the chambers where we found naio he his skeleton was mostly in this blind tunnel which is off the main part of the chamber the main part of the chamber has clearly had a huge amount of sediment removal and where sediment remains there is fossil material exposed including up here in the north-south fracture passage down here in this part of the chamber and here in the side we speculate that this was once a formation very much like the dental Eddy chamber full of bones and parts of that have been removed over time by erosion so we've lost bones we do have some ideas of where bones go to after they leave this chamber and our current excavations last month were focused right here next to Naomi found a couple of additional small pieces of the Neo skeleton we haven't gotten down past the level that we found naio at however so there may be more yet to be found the Neo skeleton is one of the most complete fossil hominid skelet ever discovered it is amazing I was privileged to be able to lead the description of it that we published earlier this year it hears Nao's mandible here is the most complete mandible from the dental Eddy chamber you can see that they are nearly identical to each other the form of the teeth the proportions of the different teeth this is a bit more warrants an older adult in this individual cranially you can see that naio is a more complete version of the cranial material we have some dental in each chamber the dental any chamber hominins are almost morphologically identical to each other they're really really similar they are more similar in things we can measure then humans from small populations today are similar so we're looking at something that's like a population in terms of its variability this is also true when you add Mayo and the other Lacetti material you don't add more variation there they look like they're parts of this same population Mayo skull from many angles it's a beautiful thing now also has a relatively complete femur and from this we know quite a lot about his size this is the best femur we have this one and we've estimated the total length of it from these I want to show you some of em and we have relatively complete endo cast about 600 cubic centimeters it's a bit bigger than any of the ones we have from the licit from the dental ID chamber okay so I don't want to go into super detail about biology although it get really really excited about biology I do want to say that this is all published in open access and you guys can download it and read it and all these charts are there and it's wonderful but I wanted to show you a few things the brain of the letti its size as you can see a smaller on average than any other species of early homo it is a bit bigger than Homo floresiensis the the very late surviving hominin species on the island of Flores so it's not by any means outside the range what we see in things we attribute to homo but it is very much on the small end it overlaps with Australopithecus species so small brain its ephemeral are very human-like in their length these are erectus ephemera and this is miletti's adult this is Nao's femur this is a juvenile femur of Naledi this is Lucy's femur so you can see that in terms of height they're human like small human but human-like in terms of their teeth I get really excited about teeth unnaturally so maybe and especially when you've got so many teeth and miletti but what are the impressive things about their teeth this is a human all the way at the far right these are all erectus teeth in between the human here and miletti and this is a habilis dentition and these are Australopithecus this is africanus a francis right so these are all hominid species and what you can see is that when you look at miletti's teeth they're smaller than the habilis teeth they're smaller than erectus teeth they're more human sized but these molars the first molar is smaller the second molar is bigger the third molars biggest that's the opposite pattern from what you see in humans it's the primitive pattern that you see in Australopithecus and when you look at the front teeth I'll tell you that these premolars did this one in particular and this third premolar looks nothing like these third premolars of any of these other hominids it is really unique I say no let me tells us things by the way it looks we don't know that these traits that are unique have functional importance we can I can't tell you that these premolars function differently I can tell you they're probably a reflection of this species history they're pointing to something strange about it Naledi had some interesting history but functionally its teeth are working a lot like human teeth more so than these other early species of Homo yeah this is two sides I love this here's no lady here are these habilis erectus things big teeth and we think of humans as having relatively small teeth in homo is having small teeth because of a high quality diet they're hunting they're using tools etc miletti is using more tools it's hunting better or something Naledi compared to other species and I want to show you the contrast here's Naledi and you can see that in general terms it looks a lot like something like habilis or something like a small erectus skull like this one from the Republic of Georgia this is a big erectus skull that next son Letty well they look really different right very different size here's a modern human skull one of the earliest modern humans and you can see that this is I'm going to show you this right next to each other in just a second so alright Naledi we worked really hard to figure out how old these fossils were last time I updated you advice about miletti I said we don't know how old they are and we really didn't the fossils are preserved extraordinarily well they say feel like Neanderthal fossils to me they don't they're not highly mineralized this isn't like a dinosaur bone or a super-heavy because it's turned to rock this is bone that's lost most of its organic content and has some slight degree of replacement with with calcite but not a lot of replacement and that tells us something but not as much as you might expect I have studied bones that are two million years old that are like this but I've studied bones that are Bronze Age that are like this as well so it's very difficult to tell from the preservation but these bones were in a soft sediment it seemed like very strange that they might have been preserved for millions of years in that context it would be very exceptional so we looked at that and said well okay we can't say how old these are but there's something very interesting and strange about the context we've found them morphologically looking at what they look like everybody said they look like fossils they're two million years old that's how old they should be we had colleagues published papers saying we believe these fossils will be 2 million years old boy that is the dumbest thing in the world to say oh the evidence points to the main 2 million years old but I'll have to wait and see what the geologists say this sounds like this this is like setting yourself up for a fall so our geology team here you can see them taking samples here are some of the flow stone samples that they've taken out of the chamber including this one which is super cool because it's got homo Naledi bone embedded in it right we can figure out the ages of flow stones because they contain uranium from groundwater and that uranium decay is part of it over time into thorium and lead and so we get an estimate how old the flowstone is when it formed and that doesn't tell us perfectly how old the fossils are but we can also look at the teeth of these fossils themselves and with the aid of a laser take tiny tiny samples across them to determine the concentration of uranium and thorium in the teeth and we can also take somewhat larger samples and assess the amount of electron traps that have been created in the crystalline structure of the teeth by ionizing radiation over time that technique called ESR electron spin resonance gives us a direct date on the teeth the absorption of uranium by the teeth from the groundwater gives us a minimum date on the teeth the uranium and thorium in the flow stones gives us an absolute age for the flow stone formation we also looked at the tiny quartz grains that are in some parts of the deposit which will absorb which will also give a sign of the ionizing radiation over time since they were last exposed to light that methods called optically stimulated luminescence we also looked at the changes in magnetism over time in the formation of the flow stones in which we can confirm that all the flow stones in the chamber reformed during the last seven hundred eighty thousand years since the last major of magnetic paleomagnetic reversal of Earth's magnetic poles right you'll add listing these because we use six different techniques from eleven different laboratories and we sent samples to these laboratories blind we sent them samples and said you tell us what you're looking at and we sent them fake samples and we sent the same samples to different labs to see if they gave us the same answer without corresponding with each other about with their methods a leave for the first time to double blind date test on a hominin fossil assemblage we have what I think is the most rigorous evidence about the age of this fossil assemblage that ever been developed and all of these methods come together so all of the different methods of this chart is too complicated to even read but but if says all the different methods tell us that these bones were laid down sometime after three hundred and thirty five thousand years ago and before two hundred and thirty six thousand years ago that flowstone that has a bit of Naledi in it is two hundred thirty six thousand years old at a maximum the ESR from the crystal structure of those teeth tells us that 95% probability the teeth are younger than 335 thousand years so those to bracket the age of the fossils those fossils are put there in the late Middle Pleistocene this was shocking to everybody because in the late Middle Pleistocene this is what everyone thought was in Africa this is the earliest modern human cranium it's about 200,000 years old from Ethiopia and here is Homo Naledi around 250,000 years old from South Africa Naledi lived there at the time our ancestors were evolving our modern human ancestors this skull from zem from Zambia is thought to be around 300 thousand years old it might be older it might be younger but this skull represents an archaic form of human big brain more than double the size of Milady's brain big brow Ridge massive face big hominid and miletti is there less than a thousand kilometers away at the same time Naledi did evolve 2 million years ago it did branch from our ancestry some time that antiquity and it survived alongside of all of these other kinds of hominids until at least 300,000 years ago Naledi was there in the human story and we note didn't notice it this is shocking how is Naledi related to us I can tell you we don't really know I don't know I'd like to put question marks on the tree I've got miletti here in his proper age right here it is 250,000 years ago just before modern humans at the same time that Neanderthals are evolving in Europe at the same time that archaic forms of humans are evolving in Africa well after Homo erectus existed but the hobbits hang on but how these are are related we don't know the reason why we don't know is when we look at one set of characters in one way these are all from the skull and the teeth these these features that we looked at when we look at one set of characters in one way Naledi looks like it belongs to the earliest branches of our genis it comes from way deep and sapiens Neanderthals erectus these primitive habilis all those forms are closer to each other but if you look at the same data in a different way the Letty looks like it's connected to archaic humans and sapiens and Neanderthals and erectus and habilis and all these other forms are out we don't know how they're connected to us for those of you do biology this is a Bayesian tree right if you walk down the hallway to genetics department and ask them how should we build a tree of these they'll say use this method and it puts Naledi as a closer ancestor to humans then erectus is but if you ask a paleontologist how should I study this they'll give you this tree and it puts a Naledi farther from any other hump I don't know the answer because none of these actually involve any of the features of the rest of the skeleton because most of these other species have no skeletons so we can't actually compare them we've come to a point where the data that we're acquiring from this evolutionary story are more from the letting than they are for any other species in our ancestry other than the under tools it's a cool situation to be in this exciting situation at the end I like it don't get me wrong I like it so much that last month we went back to the cave to dig up more of them we had some hypotheses to test about the dental eddy chamber how did the bones get in there oh yeah this is what I want this is where we enter the chamber this is a map of the chamber surface these colors are the elevation it's high here where we enter the chamber at the shoot it rapidly descends and most of the chamber is lower in its floor elevation where we dug is here where we dug is 15 meters from where we enter the chamber our best hypothesis for how the bones entered the chamber was that somebody put them down the chute the same one that we use that seems to be geologically stables for the last 250,000 years somebody put the bones down the chute and they formed as a pile here at the base of the chute and spilled off and some of them end up here but it's not a very satisfying hypothesis I'll be honest with you and the reason why is that this is where that articulated hand comes from in an articulated foot an articulated leg of a juvenile and a huge concentration of bone how did all those bones get over here 15 meters away right that's the back of the room right from where they apparently entered going through two tiny channels it's puzzling it's a real puzzle we can rule out those of you who don't know the story we can rule out lots of ways that the bones could have entered the chamber there's no mark on them from any kind of carnivore or anything that bones haven't been eaten they haven't been crunched they haven't flowed in water the sediment that they're deposited in is endogenous to this chamber it hasn't come from nearby chambers there's no wash of gravel and stuff that would come in from outside van or the way that we enter whether they got through the rest of the cave the way we do is uncertain because the rest of the cave may well have changed quite a lot but the din Eleni chamber was very much the way it is so we went back this month to dig here to test whether there's actually bones at the base of the chute because there's a logical hypothesis if the bones entered this way that should be where the maximum concentration of the mission be if Naledi was putting the bones there there's some chance that that's where an artifact might be if they were depositing any kind of artifacts with them where they enter is probably the most likely spot so let me give you just a quick clip here's our excavation in process [Music] yeah yeah this is the cave entrance where we have our command center set up during excavations the pathway to the dental Ettie chamber is back in the back there here is Becca picado working at the base of the chute within within a very short time of opening an excavation unit here which is 50 centimeters on the side Becca uncovered parts of a white chalky flowstone area with some pieces of bone and as they began to work this unit to uncover the edges of this thing this is Montebello coming through Superman scroll montebello sequani is one of our exploration team [Music] let's show you this last clip because as they were working that edge of that whitened area and determining its its extent it wasn't clear exactly what we're looking at is heard there were bone shards in it and flowstone pieces as they began to work they uncovered a set of maxillary teeth in position so it was clear that what we're looking at is a skull that is crushed they're mostly gone the skull fragments are basically down to nothing but as they continue to expand that unit and dig down at the end about 20 centimeters down they found that the lower edge of this down slope from the chute and we're literally talking about a distance like this down slope from the chute had a number of much better preserved bones including articulated parts of a hand including what appears to be an articulated part of a ribcage a shoulder we're looking in that area at the base of the chute at a partial hominin skeleton there that partial hominin skeleton remains there we expose the outline of it down to where our excavation unit ended we left it in place because we will have to recover this from the cave hold in order to study it in the laboratory we're going to have to consolidate it which is going to be a serious task because these sediments are wet and those of you know archaeological preservation know that wet things are terrible we're going to have to replace some of that moisture with a hardened plastic consolidate so that we can take this out of the cave as a whole element through the chute out and study it by preparing a laboratory get the information is there to be had in the arrangement of this skeleton but at the same time we put some of our best cavers deep into the dental any chambers most difficult to access recesses in order to try to understand that part of the system this is marina in one of those places which we've come to call Hades yeah I'm gonna skip this a second and talk about yeah okay the duality area where we excavated is here there is a tremendous jumble of fallen rock and all kinds of things back in this part of the cave system that we call chaos and behind that there are passageways that we've begun to name and as you can tell with names like Hades purgatory and limbo these are places that our team has a real problem getting into in fact only the best smallest cavers can get into these places I'm going to show you a little bit of video of what it's like to get into this stuff so here's Steve Tucker and you're gonna see him squeeze through this and as you're about to see his helmet isn't gonna fit and so he's gonna take it off to squeeze his head through this and what I want to do just is hopefully the video will cooperate zoom to the back of this and you're gonna see marina in the same passage this is all one contiguous clip but I just want to show you this is what these are like these passageways that are leading off are blind tunnels that eventually lead nowhere but you can see there - tremendous tremendous and narrow the temperature in the cave is 19 degrees Celsius sorry it's 19 degrees Celsius evening I'm going to show you this because this is purgatory in purgatory in Hades in limbo and then pandemonium the named places we have hominin fossil remains on the floor this is how our team has to work to get to them I think that that's something you don't ask a lady don't ask me how they turn around to get out I don't understand how they do some of the things that they do but you can see exactly what's necessary to get there there are places back here that Becca cannot get to because it depends exactly what your height is whether the narrow parts of your body correspond to the narrow parts of the rock it is it is crazy what's going on back in these passages and the fact that we have hominin remains on the floor of some of these very remote passages is a very interesting I can't explain it there they are so in terms of testing our hypothesis about is their bone at the base of the shoe there's bone in abundance at the base you there's articulated bone to base the sheet there's a skeleton there we've X open the second unit that down slopes slightly that has additional skull parts that may represent the same individual or may represent a second in that area of the cave that's not really what we expect for a pile of bodies actually it's too good we also don't expect these places which earn more than 30 meters from the entrance that that we used to enter this chamber to have fossil remains and there's a puzzle there and we don't fully understand the dimensions of this puzzle okay I want to quickly say at the same time we were carrying out excavations in the Lacetti chamber and I just don't want to forget that we've done that in the Lacetti chamber there was also an incredibly constrained area that we're working in this is Ellen Fire Eagle who's working in the excavation unit and you can see that she's enclosed by chert blocks coming out from the wall of this and is working a few centimeters below where she's able to be to excavate there we had to erect a ladder and put up a horizontal one for our team to lie on and excavate in this very narrow spot so we're reducing the level of sediment in this area and hopefully we'll open up part of the sediments where Nao's body was arrayed we're hoping to find additional parts of him and we have found a couple of pieces in this that might be part of Mayo so we haven't gotten there to where we'd like to be yet okay so that's the update that we have for this month I have written about it on online so you can read the summary of this just to close we have throughout the entire course of the project really worked hard to get material out to the public as it's happening as fast as we can to put people virtually into the cave while we're there and to put material out so that we can access it and of course for me working at the University of Wisconsin this is really part of the Wisconsin idea we can do no better to bring people into the science of human origins than to enable them to participate in the excavation to the degree that is possible and of course we're working in a world heritage site in one of the most difficult to access places on earth with some of the rarest most precious things we can't bring people into the chamber physically but we can use our technology to bring people there virtually and I just want to emphasize that during this expedition we were able to put internet down into the Lacetti and dental Eddie chambers and we brought school kids in through National Geographic Explorer classroom through Skype and through other mechanisms here's our team explaining how they're doing the excavations - to a school in South Africa we're bringing school kids in that those sessions are on YouTube other schools can watch those they're all there we were able to bring the public in through Facebook live using national Geographics portal and on that we had at the excavation watching us 50 thousand people interacting with us online and we continue to do as much of that as we can we've published the research in open access journals so that people can download and read them our first publications describing the levee have been downloaded and read more than 400,000 times around the world this is the deputy president of South Africa Cyril Ramaphosa I don't dare say anything about their political situation but he could be the next president we'll see but in addition to having the government engaged at every level through science and technology through tourism through the world heritage authority we have the World Heritage Site itself has put the fossils of Naledi on exhibit they're on exhibit now the largest exhibit of fossil hominins ever put on for the public and they're there for people to see and people are seeing them in huge numbers unprecedented members it is an amazing thing to stand there and have school kids come through from all parts of South Africa to see the fossils for themselves to repeat and whatever language they're they're speaking when they come in Naledi homo Naledi and and it's an amazing story that's told in the exhibition so I'm really proud of that we started that in May and that will be there at least through the year so it's been an amazing experience it's been an amazing public profile for the research it's been the most voluminous research we have in the last two years since our first publication published more than 550 peer-reviewed pages of research on homo Naledi alone our team involves more than 100 scientists around the world and all aspects of biology we are now publishing second-round science what we call the more complicated analyses than in the laboratory things like the developmental work that you saw on the teeth things like studying the actual where chipping on the teeth to compare them to other populations of humans and other primates we're now studying the isotopic signatures in the teeth we have not had success in getting DNA evidence out of the teeth we have tried very hard so far with net without success but we're very hopeful that we will have evidence from proteins of the teeth so we're going to have some tremendous evidence coming out about miletti as we move forward but what we've learned so far has really transformed the way that we think about human origins it's an amazing project it continues and and I hope that you'll all continue to follow along because certainly from the Wisconsin point of view we're going to be there working as long as we can all right thank you everyone I'll be happy to take some questions I'm gonna repeat the question after you say them and I have gone with the full hour that I started from so I apologize I always go long but but if you have to leave please don't you know don't feel like you'll be offending anybody if you have to get up and leave so I'll take you in the middle yeah this is a great question did home on the Lettie mate with us and let me tell you that we have no definite answer to that we do know that African populations derive some small fraction of their DNA possibly as much as 5% but could be less from archaic lineages that we haven't discovered we know that from the study of living people's DNA and we know it by analogy to the Neanderthal DNA when people found Neanderthal DNA in the amytal fossils and they looked at it and they said wait a minute I've seen that DNA before it's part of me when they said that and realized that most people living outside of Africa are 3 percent Neanderthal that gave them a sign of what to look for right oh that's what it looks like when you have DNA from an archaic human lineage that's been separated from us for 100 first 600,000 years right so once you saw that signature people started looking elsewhere they found the signature in Melanesia this isn't Neanderthal this is something else and almost at the same time they discovered a fossil specimen from Siberia that actually was that something else the Denyce events so we're pretty confident we know what to look for in Africa there is a sign of some archaic lineage that's contributed to some populations what we don't know is the identity of that lineage it could be something like the archaic human skulls I showed you that existed in Africa it could be something like miletti what we don't know is what it is it's a mystery we do know the genetics tell us that whatever it is that was mixing with Africans was here maybe as recently as 20,000 years ago we don't know when the lip they became extinct we found it two hundred thirty six thousand years ago at a minimum but that's not the last time it existed we don't know if they were there thousand years ago we don't know if they were there a hundred thousand years ago for sure one of the things that this really strikes you right is that we are working in the most explored region of Africa for fossil hominids I told you there are all these sites within right I take this message to heart there's something there still to discover massive major that had never been seen before in a place where everyone has been looking lots of Africa has not been looked at and you know if great fossil discoveries in Kenya Tanzania Ethiopia etcetera in South Africa there are great fossil discoveries but the areas of Africa that have actually been explored systematically are like pinpoints on the map huge areas of Africa remain to be explored and I would guess right now if I'm putting money into this I would say I think we're gonna find more other things right now ladies not the last right and the Lety tells us that there's more stuff out there to find yeah yeah why don't we alter the cave I will tell you that because it's great question right and I can tell you that from our team's point of view we have taken this very consistently with a conservation approach we can serve the natural outlines of the cave there are two reasons for this one is our teams have the right skills to get into these places where it's difficult to get into these places we apply technology to enable us to virtually get into the places and that approach is working very well for us that approach has also opened up a tremendous dialogue between us and landowners in the World Heritage Site and elsewhere that when we're exploring in caves we're not destroying things we're not coming in and taking it over we're not blasting underground you know there is of course the logistical problem of these incredibly delicate circumstances where if we apply blasting or jackhammers sorts of things you would have to do that mining engineers would bring in there's a real potential of damaging the fossils and so that's an issue but maybe the core issue is there's a real possibility that home on the letti use this cave in a special way because it was special and it's not our right to change the contours of this there's something about this that we need to understand that we need to bring out that we have to actually have the contours of the cave to to try to do so so from the science side I think it's the right thing to do to not alter the chambers you had your hand up [Music] the tooth we also did ESR testing on and it's around 800,000 years old it's vastly older than the miletti deposit we don't know whether that was an individual baboon who might have been able to access that chamber at an earlier time because the cave was different or whether it it's a juvenile baboon tooth may derive from the same sorts of owl accumulated deposits that also put a load of tiny rodent bones in some parts of the chambers so because ELLs do eat juvenile baboons so we don't know for sure this does derive from Ehsan Dodge that we did deep into to try to see where the hominid deposit went and it went down about 80 centimeters so we've dug about this far and there's a Tuesday this that dig is very narrow and so we really don't know the extent of deposit that it might relate to I can't tell you that we've recovered some additional final material in these narrow cracks and the backs of the caves of the chamber system in the Lacetti chamber we do have remains of small carnivores in addition to the hominids we don't know whether they're the same age as a hominids and in fact we don't really know the age of the hominids other than their very morphologically similar to the dental Eddie's so we speculate they're the same age but they could be a different age the carnivore remains are not except for a couple of cases found in what we think are the Naledi bearing parts of the deposit so we can't say for sure how they relate yeah [Music] like say a hundred teeth there you say you don't have the ability to do DNA testing on these how can you tell which teeth go with specimen aid which go with specimen B in which fluid specimen C does you see they have teeth are fascinating right because in your mouth your teeth actually interact with each other the teeth that are lined up in your mouth one behind the other actually where against each other and those where facets are highly distinctive to those particular teeth so they match each other right because one tooth is wearing the other tooth swearing and they make a facet that matches in curvature in extent so we can actually match those facets and reconstruct the teeth of individuals without having DNA from them that works as long as the teeth have been in long enough with juveniles that also works because juvenile teeth also wear but there's an addition to that the stage of development and another thing is that the morphology of the teeth is mirror image right so you can match the opposite sides of the mouth and you can match the top and bottom that we're against each other that way so you can do a lot you can't do everything and I would say that everything that we can join is a hypothesis some of those hypothesis are really well supported and some of them are in the absence of additional information this is the best possibility but we may find that there's another juvenile of this age in the dental any chamber those teeth some of them in the juveniles are so similar to each other that I've got two individuals one of them is probably in human terms would be something like eight years old and one something like ten years old so there's slightly different in where state there's slightly different in eruption the second molars of one are not yet in the second one was the other gistic but in every other way those teeth are more identical than my identical twins teeth they are the same teeth in two different mouths and it's just an indication that this is a again population this limitedness variability and it does become very difficult in cases like that to be certain oh yeah this tooth goes with that individual in this 2000 as well and we can always find that there are additional ones as we have found at the base of the chute we may find that we have already a tooth of that individual and so it'll be number 14 of the 15 we know about or we may find that it is yet another and will add to the minimum okay there's a question in the back yet we are using now we are now experimenting with tiny drums that will fly us into very remote parts of the cave that we can't as team enter that have tremendous video and and we're working with that and we'll see where it goes we're very hopeful that we will actually get a lot of data that way we don't yet have Walker's that work effectively in those situations or crawlers vandalism the cave is now protected it's been blocked by a public interest trust that has fist the entire property security is on site all the time and when we are working there we have security and and it's it's totally secure we've got animals now on the site we've got blessed Bach and Impala and we're getting Springbok soon so it's you know it's lovely inside the cave we have a series of gates that we don't share public details about but are designed by some of our cavers who are engineers in their full-time profession and I would say that they are sufficient to they're sufficient to keep out anyone without extreme underground mining caving type skills we do have a concern of people getting into the cave to be looky-loos or and that sort of thing and we're very serious about the security yeah no I've been behind no that's the statue yes so the question is is the open access to information that we're promoting is it new unusual anthropology is a field that has a lot of history of people being very secretive not wanting to have other people study the fossils are working on studying the fossils for 15 or 20 years without revealing what they are yeah it's very new and I would say that at every level on the team's certainly from the leadership and from the South African side we are strongly strongly committed to it I will say that we receive some tremendous pushback from other anthropologists who feel that we're not doing things in an appropriate way there are genuine feelings by anthropologists internationally it's in the United States in other parts of Africa and some scientists who work in South Africa who feel that the appropriate venue for discussing things is at private meetings where the public is not invited who feel that everything should be published in nature or science and and not in open access journals who feel that it's not valuable to get the input of the public into the work that they do I can't explain why they feel that way it is part of the history of the field as you as you indicate I can say that we have faced tremendous resistance that has been sometimes difficult to overcome but we're not going to do things differently yeah [Music] that's an awesome question the question is could come on the levee talk how did they communicate what was their communication line they the answer is in simple terms is we don't know yet we think that we will learn something about this and I'll tell you how in humans there are differences in the throat and in the ears that reflect our vocal system of communication we're different from chimpanzees we're all so different from early hominids like Lucy we have a different ear structure the middle bone the middle ear bones are differing in structure and we have a different throat structure we know that Neanderthals are like humans what we don't know is very much about what was in between we do have parts of the brain preserved as an imprint on the inside surface of the skull in some kinds of of ancient hominids humans have some changes to this part of their brain it's part of the frontal lobe but on the side and especially on the left side those changes are related to speech in humans if you're if you have damage in this part of your brain you often have trouble talking and in Homo Naledi the structure of this part of the brain is exactly like what we see in humans and that's different from what we see in early hominids like Australopithecus so we do think that there may have been changes in the communication style that Naledi may have had but we'll learn more about that when we get our work done on the middle ear bones what a lot of people don't know is that every teaspoonful of the sediment in the din Eleni chamber that our team has worked through comes out of the cave and we have anatomist and specialists who sift through that very carefully to look for any tiny evidence and in that we have found three bones of the middle ear so we're actually studying those bones now and if it's possible to learn anything about how Naledi might have heard it how it sound might have work we will discover that from these bones yeah is the single site you talked about the then the variation is just one sight couldn't simply my feeling about this if I was going to propose a hypothesis the question is it's still low variability it's just one site are you looking at an actual group individuals who are related to each other who knew each other my hypothesis would be yeah we're looking at a group that might have existed for as human hunter-gatherer groups do for a hundred years a couple hundred years and they were using this cave system during that time and they would have used some large area of the surrounding landscape and this was a place that they used and a place that they returned maybe to deposit bodies as part of what they did there but I imagine that they also used parts of the cave system as shelter we may find archaeological remains of them in other parts of the cave so I imagine that that's probably what happened and in terms of why the bodies are there I think we're probably looking at a cultural tradition that existed within a group and maybe it was there for 200 years and so you might be really looking at a snapshot really a very narrow a picture of time that this group did something interesting and they would have had relatives across the landscape but some of their populations didn't live in places with caves and some of them you know interacted with your landscape differently as humans do so that's my hypothesis I would say that we're a long way from being able to test all of that but I think it's sort of a logical way of looking at it I don't think I'm looking at something super special I'm looking at a Concilium sub evidence that points to a group and I imagine that nayo and some of these individuals from the dental ad chamber knew each other and I could imagine that the reason why they're there is that their friends thought it was the relatives thought let's make sure that the hyenas don't eat these guys you know and and that was what it was like but but we're a long way from really being able to test a lot of that yeah let's get you in the back I'm going to give you two answers to that I'm going to give you the pecuniary answer first all right the the question is why should we spend money to uncover these fossils right what does this actually have to offer in limited budgetary times what are we learning from this let me tell you first the total amount of money that we have spent as a project on the discovery excavation bringing everyone out to dig the site doing all the analysis the site have supporting South African scientists that are involved in research and bringing international scientists on undertaking an additional two years of fieldwork in the Lacetti chamber and funding a full-time exploration team in the field to find at this point more than 600 additional fossil sites in the Cradle of Humankind area the amount that that is cost is less than the amount that one of the NIH funded labs in this building Chardin requires for its work we are talking about in that time span less than two million dollars in four years of work so this is some of the most affordable science that's possible do I wish that NIH funded our work and that it was easy to get to million dollars but in fact it's very hard it's hard to support this kind of work right so so there is that but it's very inexpensive work and we're supporting the research tenure track the development of scientists across the developing world and also in the United States and Europe with more than 100 scientists involved so this is pretty cool but the other answer is this kind of work uncovers what we are with all of the troubles that we have in the world today all of the conflicts that exists all of the differences that we see among all the peoples and all of the the deeply rooted historical reasons why people are not getting along with each other in different places the one thing that we really all share is that we all come from this heritage we really do share that it's the one thing that binds us together the things that we feel deeply religion sometimes separate us they don't bind us together as a humanity we're not bound together by features I can't point to a feature that humans all have I can't even point to a DNA sequence that people all have because people vary but I can point to this history and uncovering this history is what brings us together as a humanity as a single species and I think that's important I think it's worth supporting I think that by doing this we learn about ourselves in a way that's not possible in any other kind of scientific research I look at it as the equivalent of looking out into the universe and realizing that we are but a very tiny part of it we are a very tiny part of it we're very tiny part of it that have a really rich heritage a heritage that's mostly invisible to us but with science we can make it visible with science we can take me into the dinner Lettie chamber and I can be interacting with the people there and guiding the scientific work in it because we can do that in very much the same way that NASA does we talked about underground astronauts in our work because it's really like that it's like an extra vehicular activity to get them down into the chamber and work there and they have a protocol this is very much like astronauts on a spacewalk and we guide them through remote comms and if those comms are down we stop right and very much the same way that that you do four spacewalks it really is something that is the deepest part of our origins in history is more connected to our work in the broader universe today than any of us probably would have imagined we think of people like the Leakey's in deserts who are you know processing for fossils I said that's a real part of our field and our history is the way a lot of us still work but more and more were connected across Sciences and those connections are so important in our work with the scientists we interact with around the world they're shaping the way that we think about our species they're also shaping the way that we're going to develop in the future and I think that's I think it's worth doing that was a wonderful question to end on

Channel: Wednesday Nite @ The Lab

Views: 84,349

Rating: 4.7773852 out of 5

Keywords: UW-Madison, Science, WN@tL, Wednesday Nite @ the Lab, Science Outreach, Wisconsin Idea, Anthropology

Id: 7mBIFFstNSo

Length: 87min 14sec (5234 seconds)

Published: Thu Oct 12 2017

Reddit Comments

[u/mavaction]

Thanks for this... Watching the whole thing.

[u/BlackWidow608]

I was just reading about this on the airplane! Glad to see it discussed!