welcome back to Hanover for reunions my name is Robin Alden I'm with the office of alumni relations and our team in lifelong learning creates educational programs for Dartmouth alumni family and friends around the world across the u.s. and in Hanover during reunions and homecoming we're really excited to have you here today if you would like to review some of our other programs please check out our web site on the Alumni Relations website you can learn all about the educational programs that we have today we are very very pleased to welcome professor jeremy de silva here for the talk underground astronauts the search for human fossils in south africa your feedback today is particularly important to us so when you get back home you're gonna get an electronic survey please fill that out and give us your comments we'd love to know about that so without any further ado I'm going to introduce our speaker for today Jeremy Jerry de silva is associate professor of anthropology at Dartmouth College he received a BA from Cornell University and his PhD from the University of Michigan he is a paleoanthropologist specializing in the locomotion of the first apes hominoids and early human ancestors Homan ends his particular anatomical expertise the human foot and ankle has contributed to our understanding of the origins and evolution of upright walking in the human lineage he has studied wild chimpanzees in western Uganda and early human fossils in museums throughout Eastern and South Africa from 1998 to 2003 Jeremie worked as an educator at the Boston Museum of Science and continues to be passionate about science education when he is not studying fossil footballs or lecturing on human evolution Jerry and his wife Erin are busy with their five-year-old twins Benjamin and Josephine last year Jerry was part of what National Geographic has called one of the greatest fossil discoveries of the past century and today he's going to share that story but before he starts I want to give one very shameless plug because our office of lifelong learning is also the office of Dartmouth alumni travels so those brochures that you receive sometimes those come from our office please don't throw them away one thing I want to tell you about is that next year in 2017 Gerry is going to be leading a trip to South Africa so if you like what you hear today it would be an incredible trip to go on with Gerry without any further ado please welcome professor jeremy de silva thank you all very much thanks Robyn for a really nice introduction and welcome back everyone so as Robin said I'm an anthropologist here at Dartmouth and I study human evolution by examining the fossil record so I'm a paleoanthropologist not quite a paleontologist a little bit of anthropology combine them together and I'm a paleoanthropologist so I am obsessed with fossils I love fossils and I love thinking about where we came from I love thinking about the story of human evolution and when I say that to you when I say human evolution very often the first image that pops into your head is something like this right if you google image human evolution this is what this is what comes up now this is a problem because scientists who work on human evolution know that this is not how things unfolded that guy over there is not the pinnacle of human evolution by any means whatsoever and you can think about you know where did this come from why do we have this kind of imagery where do these icons come from and actually goes back to 1965 in this wonderful time-life book called early man and this was called the march of progress and it was a new way to illustrate how human evolution may have worked and it's been adopted ever since fifty years now of reefs of folks thinking of human evolution in that with this kind of icon in mind and of course they're all these really fun plays and and you know ways of thinking about this this right that you know what are we turning into well we're turning into it you know a population that you know plagued with obesity or where we're turning into folks too reliant on technology or we're turning into Sith Lords right so there are all these really wonderful imageries that we can we can have fun with but if we go back to this original one what it implies is that humans came from chimpanzees and that's not what evolutionary biology predicts whatsoever chimpanzees are our cousins they live today they're our relatives we didn't come from them any more than they came from us right instead we are closely related to them and we share a common ancestor okay now this common ancestor was neither a human nor chimpanzee both of these spectacular lineages that exist today humans and chimpanzees evolved from this common ancestor now the DNA evidence can tell us who our closest living relatives are chimpanzees and bonobos it can also tell us when more or less the common ancestor existed about seven million years ago but only the fossils only the actual physical evidence can show us how we changed from the common ancestor into what we see in the mirror today okay so this sets up a really nice prediction or a nice test of a hypothesis of evolutionary theory that if in fact this is true if humans and chimpanzees are closely related to each other and share a common ancestor then we should find fossils of things that are neither human nor chimpanzee in sediments presumably in Africa dated back to about seven million years ago these are the so-called missing links right you've all heard about the missing links and one of the secrets that often you're not told is that the missing links aren't missing we've got lots of them we've got thousands of fossils literally thousands of fossils of things that fit this gap between humans today and chimpanzees today now some of you may recognize Lucy there is the very famous Lucy skeleton right there but look at all the friends she's surrounded by that you've probably never heard of any of those we find more and more and more of these all the time and in fact we are in a golden age of paleoanthropology or I was telling folks a moment ago that we have effectively doubled the the human fossil record in the last decade and so a lot of these new discoveries are allowing us to rewrite the narrative of human evolution and in part that's because even though we have thousands of fossils we're talking about millions of years and a million is a thousand thousand so even if you have a thousand fossils you really only have a fossil for every couple of thousands of years so imagine if I took your jaw and used it to represent all of humanity for the last five thousand years we'd be missing some stuff right we'd be missing some information so new fossil discoveries always help us fill in those gaps and sometimes they really do force us to rewrite the family tree in our in our own family tree and I'm gonna tell you about two such discoveries today but before I do that I want to give you the the big picture right what do we think happened in terms of the big picture of human evolution well we know that humans and chimpanzees are closely related and descended from one another about seven million years ago descended from a common ancestor I should say the very earliest members of our lineage are animals we call Ardipithecus eenz or root Apes and we gain some really nice insight into what these creatures were like thanks to a discovery in Ethiopia that was made about twenty years ago of an of a skeleton called our D or our tip if against ramidus and our T has a relatively small brain about the size of a chimpanzee brain but its teeth are much more like yours in mind it has a small dull canine teeth most primates have have pointy fangs for their canines and humans don't we've got these wimpy little canines and it turns out that that goes way way way back to the earliest members of our lineage the are depicted scenes also were very comfortable in the trees they had grasping toes they had long arms and long curved fingers but there are aspects of their hip joint and their foot that tell us that when they came down to on the ground they could move on two legs they did not knuckle walk so the beginnings of bipedalism of this really strange form of locomotion starts with the art of it the scenes by four million years ago the art up at the scenes evolved into a group called the australopithecines represented here by Lucy the famous Lucy skeleton they lived in Africa from two to four million years ago and they mastered bipedalism they start walking around the land not that differently from you and I do but as we find more and more and more fossils of these creatures what we find is wonderful bipedal variation it turns out different species moved in different bipedal ways so it's sort of like the the the the the cantina scene and the original Star Wars it's a two star was references now sorry about that where you know all these different forms of bipedal ism when we think that's what the world was like from two to four million years ago with these different experiments going on with these australopithecines by two million years ago Australopithecus evolved into the genus Homo these are things that have larger brains smaller teeth more reliance on technology longer legs and with those longer legs larger territories and they not only expand and fill up Africa they migrated Out of Africa they head into Europe and in Europe they evolve and didn't the undertones they head into Asia but then back home in Africa 200,000 years ago they evolved into us Homo sapiens things that are indistinguishable anatomically from you and I are discovered in sediments in Africa that are upwards of about 200,000 years ago not that long ago given this timeframe of seven million years we're talking about okay when those Homo sapiens expanded throughout Africa there was a small group that left Africa went into Europe bumped into the Neanderthals turns out that they made babies with them and absorbed them into the human population we now know that because of genetics that have been extracted from Neanderthal bones they went into Asia and interbred with a population called the Denisovans that we only know from DNA from a tooth in a pinky bone we don't know what they looked like we assumed they looked a lot like us because we interbred with them but we don't know much about their their their actual fossil Anatomy because we haven't found the fossils it's a population we know mostly because of their genes and their genes are in our genes today it's a really fascinating story so as we learn more and more about human evolution things become more and more complex which to us as scientists is a blast so what I'm going to talk about today are two fossil discoveries the first of which is a new form of Australopithecus that kind of middle group I was discussing that lived in Africa from two four million years ago Australopithecus has been known to science for a long time we've known about it since the 1920s that guy over on the left his name Raymond dart he was an anatomist at the University of the vips Lauda's rond in Johannesburg in the 1920s and he was the discoverer of the the original Australopithecus specimen is shown on the right and it's the town child it's a baby skull or a toddler really it's roughly three year old individual and he looked at this and studied this and noticed that the brain had some complexity to it like you see in a human brain even though it was small that the spinal cord left the base of the skull suggesting this thing held itself in an upright posture and maybe moved on two legs and it had those tiny little canines and he argued that this was in fact in early human ancestor the way that he was able to extract this fossil from the surrounding rock was he used his wife's knitting needles to do it that was this sophisticated technology at the time to free up fossils from their surrounding matrix now since that time there have been many fossils discovered throughout South Africa in an area known as the Cradle of Humankind the Cradle of Humankind which is illustrated here is littered with cave sites and if anyone has been has anyone been to the Cradle of Humankind right so you can go and and there's a cave right here called Stark Fontaine and sterk pentane does tours and you can walk through stark fontaine it's a really wonderful area to visit if you ever have the opportunity there are caves all over the place and many of these have yielded extraordinary or early human fossils now one of these caves right up here I'll draw your attention to this one right there it's called Gladys ville Gladys ville is one of the more magnificent caves I've ever been in as you go into Gladys Vale there are fossils lining the walls of the cave there are fossils everywhere thousands of them and a colleague of mine Lee Berger colleague and friend shown here on the right Lee Berger worked at Gladys Vale for 20 years and in those 20 years he collected thousands of fossils if something on the order of about 20,000 fossils that he collected fossils of antelopes and wildebeest and warthog and boons and elephants and giraffes but he's looking for early human fossils and in 20 years he found - he found a tooth and a finger bone and that was it that's it but he would keep going back to Gladys field because look at all the fossils in the walls eventually I'm gonna find more eventually I'm gonna find a skull of an early human eventually I'm gonna find a skeleton it was a seductive kind of place that kept bringing him back but every season he would get more and more antelope bones and he got frustrated with this and he and his postdoc job kibbe is shown on the left they decided to explore the area in a slightly different way they decided to look for new cave sites instead of going back to the old ones over and over again let's find some new caves and the way they did this was by utilizing Google Earth so this is an animation a fly-in using Google Earth heading into the Cradle of Humankind in South Africa and when we get there it's kind of brown it's light brown this is classic Africa savanna environment tall grass as far as you can see Keysha trees in the distance but every once in a while in this rather arid area it's not a desert but it's quite dry is a cluster of trees and the cluster of trees they're going to be illustrated in this animation by these red stars and the question was where are these trees that olive trees instinct would mostly where are they getting their water from that was the question this is an arid area where are they getting the water from and what Lee and the geologist he was working with realized was that water was pooling at the base of vertical cave shafts seeds would come flying in would fall in and the trees would sprout out of the caves the trees were bull's-eyes they were telling you where the caves were Lee was able to get the GPS coordinates of each of these clusters of trees he then went out on the landscape he would go out on weekends he'd go out with his son sometimes he'd go out with his dog cow and he would document the existence of these caves he was able to find 300 new caves that nobody knew existed on this landscape and many of them had fossils one of them is right here that's malapa cave that's the first one I'm gonna tell you about malabo from the sky it doesn't look like much from the ground it doesn't look like much it's just a hole in the ground that's it and yet right there in that hole in the ground two of the most complete early human skeletons ever discovered were found and the best part of this story I think is that they weren't found by the great paleoanthropologist Lee Berger they were found by his nine-year-old son this is where I found it and here's a rock that looks about the same size is it and when I turned her over a bit there was the clavicle stick out but when I saw it I didn't know was a clavicle so Matthew your father was working around here right yes and you went off wondering yeah I just followed my dog tower down here and then a big rock caught my eye so I called my dad over and when I was about 5 meters away so I was swearing and he came towards me he was like um it's a clavicle of a hominid and I it was like whoa so that was eight years ago that was in 2008 Matthew Berger is is now 17 years old he's now six foot five the big guy and in is interested in going into paleontology he had a very good start so so in that chunk of rock that he found was right the clavicle was a collarbone and many of the animals that I mentioned to you a second ago antelopes wildebeest zebra they don't have collarbones so when you see a collarbone in the rock you can immediately cross off all sorts of different kinds of animals and say all right this must be from a carnivore it's not shaped right it could be from a primate and so now baboon or early human and oh it's got the shape that we see in humans and so if you know your Anatomy could very quickly tell what bones you're dealing with and if there was any doubt we then flipped over the rock to the other side and on the other side was a lower jaw sticking out with that canine tooth and it was blunt and dull like you find in early humans so he knew right away he had an early human fossil and his son his nine-year-old son discovered just as many fossils as he had in 20 years at Gladys Vale in five minutes here so wonderful wonderful and as they kept searching through yeah yeah so the rules in South Africa are a little bit different than if you find a fossil in South Africa it belongs to South Africa it does not belong to you so the the antiquities laws there are different than they are here and so these fossils belong to the South African government and they're in order to work at this site Lee and any researcher has to get permits from from the government and so that's what happened next all sorts of permits were issued to begin to excavate at this site and see what else is there and they excavated all these chunks of rocks I wasn't part of the project yet when this was going on these chunks of rocks all had fossils sticking out of them this is extraordinary but what I'll tell you is that this science this isn't Indiana Jones here we don't go into a cave and find some skeleton just lying there on the surface of a cave the fossils are encased within fossilized soil called breccia and this is nasty nasty nasty stuff to have to chip through so all those chunks of rock went to the laboratory at the University in Johannesburg and under a microscope we had preparers who worked with this material and used these tiny little mini jackhammers to slowly grain by grain remove the the the fossilized rock from around the fossil okay is a little different from Raymond dart using his wife's knitting needles we've got a little more sophisticated now this takes a lot of time and you also can waste time if you're chipping away at rock that doesn't have a fossil on the inside of it so it'd be really nice to see the inside of these rocks and here's an example of that here's one of these chunks of rock here's a chunk of breccia and it has an arm bone right there sticking out it's a right humerus it's bone right here and a careful eye if you're looking around that rock very careful I have my students sort of look at this for a while and see if they can spot it there's a tooth right there sticking out now whenever you see tooth you say well it may be there insulation or it's attached to a skull and that would be awesome but you don't want to chip away at this and potentially damage what's inside and so this chunk of rock was brought at night to a local hospital where Lee burgers wife Jackie is a radiologist and she gave it a CT scan and when they gave it a cat scan they looked on the inside and that's what they saw that's amazing huh so there is that there's that tooth sticking out right there and that's a skull right there and you get the base of the skull so now with this information the preparator is knew exactly where to chip away they knew exactly how to get that skull out of there and what was revealed after several weeks of work was the most complete early human skull ever discovered this one right here absolutely magnificent magnificent specimen this is a replica the original I would be you know cradle and wouldn't so the the I'll tell you about the replicas in in towards the end of the talk all the replicas we've made this skull is amazing it's absolutely beautiful and as we chipped away at all the other chunks of rock it wasn't just the skull of one individual it was this skeleton of two of two individual skeletons of two individuals on the left we suspect that we have an adult female and on the right we have a juvenile male his growth plates aren't fused yet he's still growing his wisdom teeth haven't erupted yet and he would be the equivalent of a human today of about ten years old or so the individual on the left has a more spacious pelvis has smaller canines and so we think female and her wisdom tooth our teeth are not only erupted they're all born down so we think this is an adult probably in her 30s when she died they are lying right next to each other in the cave we suspect they actually fell into the cave together and this may very well be a mother and son though that's exceptionally difficult to test in the absence of DNA and we can't squeeze DNA out of rocks and that's what these things have become their fossilized so no DNA out of these things but what was great is that their Anatomy was something I'd never seen before the anatomy was entirely different from what other researchers had ever discovered in a fossil of an early human before and because their Anatomy their head-to-toe Anatomy was so different they were named a new species of Australopithecus Australopithecus sediba sediba means wellspring in the local language and those are the teeth you can see on the left and right the adult female there's the worn-down wisdom tooth and here's just the socket for the wisdom tooth not even erupted yet in that younger individual this is around the time that I get involved with this project and this was such a fun project to be involved with he goes head to toe we had a different kind of animal we think moving in a different kind of way this skull was brought to France it was given a high-power x-ray and a sight an x-ray facility in Grenoble in France and on the inside of that skull was the perfect fossilized replica of a brain of that individual is not a fossilized brain what would have happened is sediment filled up the skull in the exact same size and shape of what the brain would have been so we have essentially a cast of the brain the brain is rather small this is one of the few data slides I'll show you guys on the x-axis is time so that's three and a half million years ago that's today y-axis is brain size every dot represents an individual fossil so we've got lots of them lots and lots and lots of fossils in unbroken chain connecting humans today all the way back to our ancestors in the past chimpanzees are represented by the red line here of brain size about the size of a can of coke 385 cubic centimeters and chimpanzees Australopithecus sediba has a rather small brain Australopithecus in general have brains only about 20% larger than a chimpanzee and this is the beginning now of the brain increase and so it's right at the base of that increase happening in genus Homo in Australopithecus sediba the hand of Australopithecus sediba is wonderful the thumb is long and robust and it would have allowed precision grip it would have allowed the pad pad grip that humans used today to do all the incredible things that we do chimpanzees can't do that sediba could absolutely do that but the body was different the arms were quite long the shoulders were ape-like suggesting it was still comfortable in the trees the pelvis was different from anything I've ever seen so was the knee so as the heel and so is the mid foot and I started working with the physical therapy team so a physical therapist group trying to assemble how did this thing move how did this thing walk and what we've argued is that this was engaging in a form of bipedalism we call hyper pronation this gets a little technical anyone who runs knows about hyper pronation and that you shouldn't do it but we think that this creature was landing on the outside of an inverted foot and then its foot would roll in and its knee would roll in and its hip would roll in and it would walk kind of in this awkward sort of way now why did it walk this way well we think the the the the species is still equipped for climbing trees and in living in the trees at night to get away from predators and also where it was getting its food and I'll get back to that in a second but I was struggling with how to how to communicate this with how to you know tell folks so you know whether it's students or in a public discussion like this or even my colleagues to demonstrate how this walk looks so that others can test this idea test this hypothesis because I may not be right we'll see so what I've been doing is working with the dollies Center here at Dartmouth with a student Aimee Zhang who is interested both in art and in science and what she's been doing is working with video game software to animate this thing and bring it back to life it's two million years old I didn't mention that it's two million years old we dated this sediment surrounding the rock surrounding the fossils using uranium-lead dating of the of the limestone and so you have a creature walking again after two million years it's really a sense chills down my spine absolutely love this idea of bringing these things back to life and working with the Dartmouth student as as talented as amy has allowed us to do that this is just a prototype she's still she would be horrified at this she's still working on this animation and getting it to look more accurate now I mentioned a second ago that we have evidence that they're getting their food out of the trees and you say well how do you know how do you know that this skull is so well preserved it still as food stuck between its teeth so we thought that that brown stuff there was just dirt and you clean it off and make the teeth nice and shiny and white we have a there's a there was a PhD student would recently done her dissertation on plaque that was still present in neanderthal teeth and thought well hey if they're present in Neanderthals yeah this is a lot older but why not have a look and sure enough that is plaque you scraped that off the teeth look at it under a microscope and it preserves these little remains of plant cells called phytoliths and phytoliths are very resilient they last two million years and they have a specific shape depending on the plant cell that came from and so we can tell that before he died he ate fruit and leaves and bark this stuff you get in trees so he was presumably up in a tree eating came down moved maybe with his mother across the landscape and we think they fell into this cave there's evidence of breakage on the arms and the skull and parts of the elbow of these individuals we think they fell into the cave and that's how they died now we now know that they weren't alone either that the two of them were not the only ones present in the group as we've gone through these chunks of rock we have found evidence of an elbow this is an elbow from an infant roughly one year old individual this is an ankle from a toddler and this is a shin bone from another adult so we now have an infant toddler preteen and two adults it looks like we have a family group and we may have more and we're going to find out more as we continue to go back and continue to dig this is an incredibly exciting site with a new species that we're going to be digging in the coming years now to me one of the most important and exciting aspects of this is that a beautiful structure has been built over that pit in the ground over that hole in the ground that's shown here and students from Johannesburg school children can now take buses up to this site and they can watch the paleontologists as they excavate and they can become inspired to do this themselves even perhaps more important for for this audience is that we've been inspired to bring Dartmouth students and so in the fall of this year we are teaching a class called anthropology 70 experiencing human origins in evolution this has been funded through president Hamlin's experiential learning initiative through decal and we have been encouraged to not only teach the students we just selected them there 15 students we're gonna teach them in the classroom in September October November about field methods and how it is you find fossils and how do you know it's a human versus a versus a carnivore versus a antelope versus a wildebeest any of those things they're going to learn all the methodology and then after Thanksgiving we all meet in Johannesburg and we go out to malapa caves and we dig and so they're gonna have this experience of actually digging at this site and this is again being covered by by president Hamlin's experiential learning initiative through through decals this is going to be fun it's going to be really exciting to involve the Dartmouth students in this incredible incredible site so that's kind of the halfway point that was one fossil site that I told you guys about but remember Lee burger found 300 new fossil sites 300 new caves so what about the others and what about the caves that people already knew about we need to explore those a little bit better too this became this sort of daunting endeavor of cheese there's a lot of work still to be done here where do I even start and so what Lee did was he formed a relationship with the spelunking community he reached out to folks that cave for fun and he said hey here's my card if you happen to bump into any fossils any bones at all I know you don't know anything about bones but if you happen to bump into any bones at all give me a call let me know well in October of 2013 so this is almost three years ago now two and a half years ago these two guys says Steve Tucker and Rick hunter these two guys are amateur spelunkers they go out on weekends in cave they were in a cave that was known to the world this wasn't one of these 300s this is a cave called rising star cave people go there for caving experiences and they decided to go into an area of the cave that they hadn't been to before there was just tiny little crevice there and they squeezed through the crevice and down a chute and into a chamber and down into that chamber when they got into that chamber they saw that remember I told you how we never find skeletons just lying on the surface of the cave because the skeleton just long in the surface of kick so we sent this picture to a number of us and said what do you think and I looked at this picture and thought oh geez this is that this is a caver this is a recent person who died because we don't find fossils just lying on the surface of the game but the the the the the aspect of the anatomy that changed my mind were the teeth okay humans today have very small wisdom teeth it doesn't feel that way when they're coming in but our wisdom teeth are actually the smallest of the molars the first molar is the biggest and the second molar is usually smaller than the third one is usually smaller so we have a gradation of our molars where it goes the biggest is the first then the second then the third our ancestors it was the other way around the third was the biggest the second was smaller than that and the first was the smallest you can look at this John see that that third molar is bigger than the second and bigger than the first and so it has the gradation of an ancient species but there it is just lying vulnerable on the surface of the cave and so it was realized quite quickly that an expedition needs to be launched that can get this skeleton out of here and protect it as soon as possible because this is valuable to science but it's just lying there and could be quite vulnerable to the to the elements now here's the problem Rick and Steve don't know anything about bones they found this they took this picture this is great but they don't know anything about excavating properly excavating fossils we needed people who knew how to excavate we needed people who get fossils out of the ground we needed people who knew the difference between a human bone and an antelope bone and a zebra bone and a baboon bone so we needed somebody who had a degree in archaeology anthropology paleontology geology something like that we needed somebody who had caving experience who wasn't gonna go in here and freak out okay so that eliminates me there's no way I'm doing that and we needed somebody who could squeeze through that gap in the rock I told you about what I didn't tell you was that it was only seven inches wide seven inches so that sounds crazy I want to show you what that looks like so then on the other side is something called the shoot and that's a 40-foot drum right on the other side now that that shoot fortunately fortunately is tight enough that you can treat it like a chimney and kind of wiggle yourself down it's not a freefall but still so how are we gonna find these people right who has that set of skills and how are we going to find them and Lee burger came up with the answer he figured it out he put the he put an advertisement on Facebook he said I'm looking for skinny scientists I'm looking for skinny scientists who know how to excavate who know their Anatomy who can come to South Africa at the drop of the Hat just drop whatever you're doing to come to South Africa for three weeks for an excavation people who have caving experience and you need to be able to squeeze through this seven inch depth between these rocks and he found and and maybe I'm wrong on this but he found as far as I'm concerned this six human beings on earth who fit this criteria and there they are these are what I call the or what folks have called the underground astronauts and that's why I titled the talk the underground astronauts six women these six women scientists came to South Africa in November of 2013 to excavate what we thought was a single early human skeleton we thought it was a single skeleton just lying there on the surface of the cave they went into this chamber they went into this cave they explored this cave they trained quite a bit with cavers who knew the area pretty well this was done in as safely away as possible and this is what they had to do so this is where they start right up here and then you walk in and this is where I stop and turn around thank you and the first real problem is Superman's Chrome Superman scroll is only ten inches high and you have to go through like that which is why it's called Superman scroll so you get the Superman pose and off they go through then they get two dragons back which is filled with all these jagged rocks that's the 7 inch squeeze and there's the 40-foot fall into the shoe into the DNA leading chamber and then a deleted chamber is where all the fossils are okay now after they get the fossils they're gonna come back out keep that in mind you got to go up the chute through the seven inch gap and back down dragons back back from Superman's crawl they got so good at this that they could do it in 20 minutes I took in 20 minutes to get down into the chamber more to get back back out these are the kind this is the kind of environment they would work in lights were put down there video cameras were put down there as well it was also oxygen or co2 detectors that were put in there to make sure that they had enough oxygen these were incredibly difficult conditions and they were amazing they did absolutely incredible so every time you see a flag they would find a fossil and put a little flag in and then these are their digging tools there so you got a plastic spoon there's a you know tiny little you know almost like a little dental equipment they've got toothbrushes that they would use so we don't go to fossil sites with shovels and it's a big misconception we go with these tiny little tools to get the bones out of the ground and everyone who couldn't fit in there watched it on TV that's that's everyone else just observing and also giving recommendations of what fossils to go after in what order so they would get a fossil wrap it up in bubble wrap and then put it into like a little lunch box and once the lunch box was full somebody would carry it up the chute he get to the top of the chute it would be handed off to a researcher couldn't fit down there but wish they could and they would go through and document the anatomy of the bone what bone is this it's a mandible it's an all no it's a it's a femur or something like that and that's how this would go for three weeks and what I loved about this was that it was live-tweeting so that the world the folks who knew about this this was on national Geographics website and those who sort of had the right timing saw this could follow what was going on it was the first time in the history of our science that we could actually invite the public into a great discovery because usually discoveries are really you know they're lucky you just stumble upon something so the Lucy discovery for instance they didn't know they were going to find Lucy that day but we knew this day we were going to excavate the skeleton of an early hominin and so the whole thing was tweeted and so here we have the the the statement of staring at a beautiful mandible fragment with dentition science tent is all smiles so I want to show you what those smiles look like they're really telling so here's Lee burgers smile and then Lee hands the mandible off to his cranial dental expert person who says studied mandibles and teeth for his entire career Gerald the writer at Texas A&M and here's Darrell's smile this thing didn't look like we thought it showed it didn't look like it should from the picture this thing was different nobody had ever seen this kind of anatomy before again this was a different kind of creature yet again and meanwhile more and more fossils keep pouring out of the chamber and soon what the underground astronauts found so this is Beckett Marina what Beck and marina ended up excavating on day 2 was a second right femur nobody has to write femurs and once you get a second right femur you got a second individual we have multiple individuals it's not one skeleton down there it's multiple skeletons and then sort of it's what well how many how many do we have down there and they kept saying there are more bones down there there's so many bones bones down there so by day five a hundred fossils had been pulled out of that cave now this doesn't sound like a lot you say well I have 206 bones in my body a hundred a hundred does it sound like a lot but I put up this image here to give you some perspective on how rare human fossils are that's Olduvai Gorge in Tanzania it's one of the most famous early human fossil sites ever found most people have heard of Olduvai Gorge that's where the Leakey's really made their name and at Olduvai Gorge folks started working there in the 1930s it really picked up pace in the 1950s and into the 1960s that's when the linkies were doing most of their work so we're talking about 50 years of constant excavation all divine and in 50 years they found about a hundred human fossils that's about the pace that's about how often we find these things about a hundred fossils for every 50 years so two fossils a year and it's a good season if you've pulled that off we match that in five days so this was an extraordinary kind of site and meanwhile we kept finding fossils 500 fossils and then it was a thousand fossils and at some point Lee said all right we're done we have enough and the underground aster I said but there's still more down there and he said we gotta find out what these things are first so you shut down camp this is the last image that was tweeted and maybe the Lighting's not great but you can see that's a that's a row of teeth right there that's a jaw those are ribs it's a femur sticking out of the ground in March becca and marina went back down in there they got that jaw and they also excavated a complete hand in the complete foot so we now have 1,500 fossils we have effectively doubled the entirety of the human fossil record doubles in in in a in a month-long excavation 1,500 foxes absolutely extraordinary this is what they look like all laid out now those 1500 fossils we now know by studying these bones very carefully come from 15 different individuals we have juveniles we have lots of children in this collection which is incredibly unusual to have fossils of children and we have lots of older individuals and we do have some prime aged adults though though not nearly as many it is an extraordinary set of fossils I've never had an opportunity to work on fossils like this before this was mind-blowing to go to into South Africa and see this many fossils lying there on the table it was overwhelming where do you even start usually I would go down there and spend two weeks to study five fossils and here I had a hundred leg bones and over a hundred foot bones to work on I didn't know where to start where do you even begin yeah different bones that's a composite that's a composite yeah the bones are all jumbled together down there we have hands in articulation I'll show you an image of that in a second we have feet in articulation we have some bones that we know go together but it is so densely packed with fossils that an arm from this individual you know mixes up with an arm from that individual and we get these skeletons all jumbled it's an unbelievable jumble of fossils yeah yeah yeah so that's exactly what we were wondering is how in the world to get this many bones this many fossils in one spot let me tell you guys about the anatomy and then I'll move to this really really strange circumstance of how these bones we think how these bones all accumulated together so right so we had this big problem of of how we gonna study these things and get them out to the world in a reasonable amount of time this is these are I mean there's decades of work here these are dissertations here that need to be done but we didn't want to spend the time doing that we wanted to get these out to the public as soon as possible but we wanted it to be done well so what do we do well you invite more people you just get more people more recent PhDs get as many young scholars as possible who are hungry and have datasets and all they want on new fossils to work on and get them to South Africa so we convinced the early really convinced the South African government to hold a workshop and 60 researchers recent PhDs came to South Africa for a six-week workshop and and we just said let's figure what this thing is let's figure it out and that's what happened in May and June of 2014 this is the skull team led by Heather Garvin right in the center she's at Mercyhurst and she worked on the skulls and the teeth for that time this is the thorax team led by a guy from Spain Marcus mr. Shawn in the middle trying to figure out how those vertebra and ribs come together let's reconstruct the chest and the thorax I'll I was working on the the leg and the foot of this thing we had another researcher from the UK working on the hand so we had people from all over the world descend on South Africa to put this creature back together again and this is what we came up with the skull is incredibly small we have a brain size of this creature of about 500 cubic centimeters which is a little more than a third of your brain size okay so this is home another moment I'll tell you the species name is second so this is the the brain size here which hopefully you can see is smaller than mine a little snout II a little snout II but but more or less this is a very human-like shape to the skull and this is an adult we can tell from from the teeth the teeth themselves are stunningly human-like it's not real it's a replica the teeth proportions are very human-like the canines of our human like the incisors are human-like the only difference again is that that third molar is the largest of the molars and so that makes it a little more a little more primitive this is the last data slide I'll show you on the x axis there is tooth size and on the Y is brain size and in general in human evolution our Australopithecus ancestors had small brains and big teeth and then as you move through human evolution in general we get big brains and small teeth and we think that diet and dietary changes teeth drove brain size changes in large brain size so the bigger the brain the smaller the T if the smaller the brain the brain the bigger the teeth and that's how fossils have worked since we found them until we found this thing and this thing is different this thing occupies that X right there where it has small teeth and a small brain we've never seen that combination before and it actually flies in the face of some really broad theories we have about how human evolution has worked in terms of brain enlargement so that's fun for us to find something that doesn't quite fit the mold the hand again quite human-like this is this is the hand and anyone is welcome to come look at these afterwards the hand here has human-like proportions a big robust thumb but the fingers are really really curved again suggesting some reliance on the trees perhaps at night I've been working on the legs and the feet of this creature reconstructing gait reconstructing how it moved and it moved a lot like us it didn't move like that other thing I was telling you about it's much more like us long legs it has human-like joints in the hip and then in the ankle for the most part and the foot is stunningly human-like with the exception of both the individual we have this complete foot from and many others we have up here to not have much of an arch and so the arch of the foot seems to be absent in these in these creatures but the proportions and all the ways that these bones come together I like what you see in humans today once again it was a combination of anatomies we had never seen before and so we named it a new species and we called it Homo Naledi Naledi means star and it's after the cave system where it was found rising star the rising star cave system Naledi means star and when you put muscle where we know muscle is and you put skin where you know skin is and then you apply a little artistic license to the reconstruction that's more or less what these creatures would have looked like and so that's the artistic rendition of home and Alethia this came out in September of last year and when it came out I figured people would be interested in it I had no idea it was going to explode the way it did this was everywhere this went viral it was so much fun to have former teachers and and former students of mine and cousins I had never even heard of emailing me and and saying oh you're part of that know anything I was so cool you know above the full New York Times is on the cover National Geographic and then you know you've made it big time when you're in the onion the timing couldn't have been better I was starting here at Dartmouth in September my first class was in September and two weeks later this enormous announcement comes out and I was teaching the introduction to biological anthropology course at the time and and when it exploded like this my students were so interested in asking questions I talked to the folks at decal who were interested in experience of learning and I said well let's get laid here let's get lay here to talk to the students about this and so in November he came and he gave him a public lecture and he gave a talk to the students and then he had lunch with the introductory students and he inspired these students and these are many of the same students who are now taking anthropology 70 in the fall and are going to go to South Africa lick their hoods so between these you know inspiring discoveries that have been made I think we've made a real impact on some students that probably were just taking ants 6 to satisfy some distribution requirement and and now that you know we've derailed their plans of being of being economists or something like that I'm sure their parents are thrilled with me so so what is homo Naledi well we don't really know homo Naledi appears to anatomically fit the gap between an Australopithecus and Homo erectus there they were they were reasonably tall the male's at least were about 5 feet tall the females were a little smaller than that the proportions were like us long legs shortish arms very small brains though which is curious again in anatomy we had never seen before where it fits on the family tree we're not entirely sure so there's homo Naledi with a couple of big question marks around it and one of the reasons that we have these question marks is we actually don't know when homo Naledi lived we don't have a date fossils don't come with labels these things don't have you know back pockets with licenses that we can look up when they were born or so we have to rely on the geology around the fossils to date the fossils to know when these things lived and when they died and very often what we do is we rely heavily on the fossils of other animals found around the ones we're interested in and we find zebra bones we find antelope bones warthog bones and we say oh yeah this ancient warthog lived in this time period because we've dated it at this other site and this ancient giraffe lived in this time period and you'll find the two together then this must be about 1.8 million years old or something like that you logic out the time period based on the bones of other animals there were no other animals found in this chamber 1,500 fossils and no other animals remember Gladys fell at the very beginning half hour ago I was telling you about Lee's first site where all he had were other animals and no early hominids and now he's got the reverse problem of only fossils of early hominids with no bones from other animals or at least no bones from any large mammals and so this was a huge huge mystery of how in the world did these fossils get down there into this chamber and we puzzled this over and we said well okay maybe there was a carnivore that specialized on eating Homo Naledi they grabbed him and dragged him down into this cave and munched on okay maybe was that well you'd see bite marks all over these bones and we don't so the nobody okay cross that one off all right maybe there was a catastrophic event a whole bunch of Homo Naledi is walking across the landscape and there's a really bad flood and it washes them all down into this chamber okay that was the case you'd have sticks and debris and rocks and junk from the surface also washed into the chamber and instead we have this fine fine silt we don't have any evidence of a catastrophic event so then we said all right maybe they're the ones that went down there and they got stuck they got trapped they were exploring who knows what they were doing and they got down there and they start to do okay if that was the case all of the bones would be at the exact same geological layer and they're not they're piled on top of each other and there's sediment between them meaning that this happened over a period of time we don't know how long but it happened over a period of time and the only thing we've been able to come up with them we might be wrong but this is how science works you come up with a hypothesis and then it's tested when you have more evidence right now the hypothesis is that this was deliberate disposal of the dead that a homo Naledi in the group would die and they would carry individual down into the chamber the way they would do it is they would circumvent this this region here there's actually another way to get two dragons back so they would come to the base of dragons back walk up with the body and shove it through here like a mail slot and the bodies would then accumulate over time down in the Dino lady chamber if this is true if we're right then we have an incredibly sophisticated behavior a repetitive behavior happening in a species with a stunningly small brain and this is something that we often have restricted to only humans only Homo sapiens will will dispose of its dead and if we're right then we now have evidence that a rather small brand creature was already doing something behaviorally complex and sophisticated it's a fascinating possibility and we're still thinking of ways of testing it now the last thing that I'll mention about this site itself and then I want to have sort of sort of you know finishing remarks is that the cave itself has has so much more to excavate so we have excavated or the underground astronauts have excavated an area about the size of a desktop in a cave about the size of this stage okay in every other area is jam-packed with fossils so that's illustrated here with those little those dotted lines that's what was excavated in every other area is packed with fossils so if you can pull 1,500 fossils out of that little box can you imagine how many more fossils there are so there are many many many many many many many more fossils still down there to recover the other thing I want to mention is that these fossils belong to everyone these fossils don't belong just to the South Africans these fossils don't belong to the researchers who found them these are our ancestors they belong to everyone and we've been really passionate about that and so what we've done is we've laser scanned a hundred of the best fossils jaws and skulls and leg bones and foot bones and we've made them freely available on this website morphix org so you can go to morphosis org and you can look up Homo Naledi and you'll have a hundred fossils that you can then download pull it onto your desktop you can have it as your screensaver you rotate a fossil you can bring it to a place that does 3d printing and you can print out your own Homo Naledi fossil it's a really good gift for the holidays that's what my family - you gonna get I'd hold on - Lettie jaws and not again dad so so I mean we really are passionate about about making sure that folks know that these fossils are really belonged to everyone these are the world's fossils so this is the monster museum right over to Norwich and when Lee came he donated a set of home and Eleni fossils the skull and the hand and the foot and these are so inspiring to the to the kids and to the adults to everyone who go there and look at these fossils because really I mean these are telling us about us these are telling us about the human story so I'll end with the following observation that these fossils I've talked to you about 2,000 fossils today these fossils from two different species okay brand-new species that we didn't even know existed prior to finding the fossils these fossils were discovered in one of the most searched areas on earth for these things right and they were discovered by a nine-year-old and a couple of amateur cavers so can you even imagine how much more must be still out there waiting to be discovered this is a spectacular awakening should be to everyone to students into everyone that there is so much more about our evolutionary history about ourselves about our world and about our universe that we still don't know so thank you all very much if you would just use the mic to ask questions we'd appreciate it so we'll take turns that way do we have some questions yes so you've told us about the length and the width of the space that was excavated what was the depth that they excavated to get 1,500 bones out of it's about a meter yeah not certainly not for a team not very deep at all it still blows my mind that in that limited space they were able to pull up jam-packed and it's made figuring out which bones go with which individual is incredibly difficult you know it's a fun mystery though my challenge when I got there was to was to take all of the foot bones and the legs and turn them into feet and legs so which bones actually go together and you apply a lot of the skills you learned in kindergarten about shapes that hey this shape goes with that shape and you click them together and oh these two go together and that's how you assemble these into into actual skeletons things are looking up however we there's a there's additional information that we're getting from from excavations that have happened since this and it looks like we have some associated stuff so there is going to be more there's so much more it's gonna be fun hi this is a kind of stream-of-consciousness question I apologize that your thought is there the hypothesis is that they were tossed in dead as their chance they could have been alive when they were thrown down there and if they were tossed in dead would you typically expect to see some sort of cause of deaths would there be like signs of violence with an animal or another humanoid or so there's no evidence of any violence and and that's something you can actually pick up on the bones reasonably well because bones that are fresh break in a particular pattern breaking away that are different than bones that have just been lying on the surface for a long time they crack in a different kind of way it's almost like if you take if you're looking for firewood and you find a stick that's been out there forever it just cracks easily but you find a fresh one and it gets you know you get a green stick right and gets these these green fractures bone does the same stuff so you can tell the timing of a bone breakage based on that and you can often tell in a forensic context whether it's it's something that was violent whether it was done by humans or humanoids or done by a carnivore you get the the bite marks no evidence of that whatsoever but there is interesting patterns of damage on the bones that to me at least are consistent with with the bones already being skeletonized and things then hitting them so bodies additional bodies coming in fits with that with that observation and the bones cracking as a result of that one of the other interesting things that we've observed is that the hand and feet people love this site the vertebra people are not too pleased and you'd think geez got 15 individuals and you got dozens of vertebra you do the math and they should be vertebral over the place and they aren't they're only a couple there aren't many ribs either the shoulders are damaged and then the pelvis is damaged but the feet in the hands of Garten gorgeous teeth are gorgeous and we've talked to a lot of folks about this and they said well this is consistent with open-air burials and an individual who dies and is then kind of rotting on this on the you know not berry but rotting in the surface somewhere you get this kind of nasty brew in here and it can it can damage the bones themselves that are in that vicinity where his hands and feet might mummify they might dry up and mummify and keep all the bones in perfect orientation and keep them well preserved so that actually fits reasonably well with the idea that the bodies were pitched in already dead got in there and then rotted in in in the chamber but we have I mean there are forensic pathologists who look at insect damage on bones who look at all sorts of things that that and their work on this material now to try to answer these questions of what was the state of the body when it was when it mate when it got into the chamber however it did what was this is a to the body when it happened hopefully that answers your question yeah oh oh sorry I should yeah just I'll go ahead and give me difficulty in accessing the chamber once these bones were located I wonder well why don't you just drill into the chamber so right I'd love to go down there so here the the the two reasons that that that was not done but discussions are happening now on how to do it the the first was you don't want to ever disturb a context unless you really understand what's going on so you want to keep it as pristine as possible so you worry that if you did you know destroy an area just to gain better access to the cave you've actually removed a key piece of the puzzle of how the bodies get down there of what the chamber was like years ago of how to date this system so we worried about that and so we made the decision I think it was the right one to not make any changes at all the other big fear was that if you do you know do some drilling if there's controlled explosions to try to remove some of these chunks of rock you could make the whole system unstable and you can get a cave collapse and if we got a cave collapse with with folks down there that was it's just I can't even imagine that so we didn't want to think about that so it was kept the way it was it was I don't want to say it wasn't dangerous because it was but the the women became so skilled at doing this work that we became more and more confident that this was the right approach at least for now in the future there there are discussions on how to maybe widen some areas and make this more accessible so I realized you can't date this latest find but now you've had two new forms of early humans discovered and relatively close proximity is the latest thinking that they existed around the same time he had just lots of versions of us or could have been more of a sequential thing evolutionary I mean evolutionary perspective what's these two particular species I don't know the answer to your question but we do have well enough dated sites throughout Africa to show that multiple species of human coexisted throughout time that that the unusual thing is what's happening right now but this is this is the strange part of human history is that there's only one species of upright-walking ape and it's us and and and you know there's not too much data on this but I don't think it's too much of a coincidence that that once Homo sapiens arrived on the scene some of the others went extinct we have a tendency to do that we're very good at extracting resources out of our environment we're really good at out competing competitors and we would have had competitors out there it would have been these other things and we're really good at eliminating them and I think that's likely what happened there was a little species called Homo floresiensis that lived in Indonesia till only about 50,000 years ago so quite recently and then they went extinct Neanderthals now we enter bread with Neanderthals but you can tell anatomically the difference between a homo sapiens and Neanderthals and then we move into their territory and they're gone but we're still here the Denisovans in Asia were there and then and they're not anymore but now we are so if you go back in time though you would have you know homo erectus coexisting with a number of these species you go back in time even further and you have different species of Australopithecus coexisting probably filling different niches some more trees somewhere on the ground some more in Lake Shore environments some more up in the hills so they would have filled niches exactly how they interacted with each other though we have no idea and it's one of the great questions that I think we have is you know from an ecology standpoint how do you fill a landscape with a bunch of things that are becoming better and better and better at exploiting their environments because that's what we do in our niche so it's like yeah so that's what we're finding is there was you know this idea of linearity of human evolution there was only one thing at a time gone yep the fossils are telling us an entirely different story yeah my question actually follows on nicely from what you were just saying because when I first heard about this I well I've been troubled about the size of the you know that a creature with a brain size that small could be engaged in deliberate disposal of the dead I'm an archaeologist do paleoanthropology but study enough of this stuff that it makes it seemed very odd so I've I have a theory that I haven't heard voiced but could another specie another hominid species have been disposing of these little guys right in there and we don't know I mean they don't know right Yeah right maybe some of the bigger brain who you know had a relationship with these these things keep dying and they keep attracting scavengers let's you know get rid of them let's get them out of here I guess we don't have any evidence of anything the the you know it's it's hard to get into the heads of these things if in fact this is what they were doing there's nothing there's no evidence of grave Goods there are no tools down there there are no sort of strange bones showing up down there you can tell that you have a human burial site because all of a sudden there's some antlers you know next to the the body and how did that happen well this is really beautiful quartz hand ax or something like that it's okay this was that yeah that was deliberate nothing like that at this site what we need to do to answer that question is date this site we need to know when these things existed to know who their contemporaries were to know who may have also been doing this and really to look at more of these fossil sites and figure out if these things were overlapping in habitats and on the landscape with other other other species now just to give you a heads up we are very close to having a definitive date on this site we're very close we've had we've used three methods to date the site labs independent labs around the world have been sent these samples and we've now gotten the samples back or were their results and the team will be close to submitting a publication very soon that the date were close on dates there was a paper that came out just this week that only based on the shape of the skull only based on the the anatomy of the cranium suggested that this was 900,000 years old that was the argument that it was 900,000 years old so that's the ballpark we're probably talking about based on Anatomy but that assumes that our narrative is right because you can find something that doesn't fit the narrative and that keeps happening in our fields and it means that things were a little more complex and interesting than we thought so we'll see once we get the actual numbers in I was wondering if the bones showed different ages of the individuals or were they mostly adults they're all over the place we have a we have an incredible cross-section of Ages represented there are a couple of vertebra from an infant so we do have an infant in the collection but not much of it little teeth as well or tooth nothing you know the roots have a important just the crowns of a deciduous tooth that suggests we have something of an infant we have a number of children ranging from say three years old up to about seven years old disturbing number of children I'm not used to working with kid fossils usually I work with fossils of adults or older individuals and it's you know okay they they live their life and and here we have these you know five year olds and that's a that's it's tough to work with actually they're fascinating and they tell you about growth and development and the species and they're really important but it's hard not to not to feel something you know what you're working with a little kid fossil we do have some prime aged adults so some adults who are early 20s mid 20s 30s or so we have some of those but not many and then we have a large number of older individuals and so the the demographic pattern that we have actually fits a graveyard reasonably well you know so you know before well if you go into any New England cemetery right and you see lots of kids and lots of elderly and not as many in between and that's the same thing we're seeing here so it's it fits that pattern of this being a deliberate disposal site but but I don't want to you know read too too much into that but that's that's what we're seeing is kids and some adults but lots of older adults given how many bones are still left and the publicity around the K site how is it being secured and keeping people from going in there now yeah so the 7h cap helps you know I think it Ward's off enough people however there are bars that have been placed in front of the entryway so you can't you can't even get into the ends of the entry unless you're the key and just the university has the key to get in so it's very difficult to gain access also the land that it's on has is gated off so it's difficult to get on to the land as well but this area is only 45 minutes outside of Johannesburg and so it's you know it's close to one of the biggest cities in Africa you've got these incredible sights but it's one of those circumstances where even if you took a you know somebody with with Mal and ten and said okay go find some hominid fossils you know there people have been doing this for decades and haven't found one so so it's difficult to do but as we find more and more of these hotspots it is becoming we're becoming more and more aware of the possibility of of these becoming sites that could be places were pit yeah people could go and steal fossils and try to sell them on eBay or something and it's horrifying but that happens in paleontology so dinosaur fossils are common enough that that happens and so I think we now are reaching a point where we're finding enough fossils and getting good at finding the sites that this is going to become something we're gonna have to contend with not yeah I don't think but but yeah if there was an easier to access site then maybe we have time for two more questions I'd hear excuse me so thank you for your presentation this was was wonderful I one comment and then a question I loved the I'm gonna an economist myself and so if I by training I so I love the scientific inquiry piece and I loved how technology right before Google Maps and but but you had to still figure out the tree piece right that that that's how you then identify these these caves but the technology sort of helps you do that do you have anybody from anybody with a public health background or like public health historian background this is built reason why I ask this is I spent a lot of time with public health people and this your idea around the cemetery around the body disposal piece and it being deliberate it you might want to talk if you don't you might want to talk to some public health people they because they may have been you know look at this and say we you know give you some clues as more clues as to you know the kind of weather a plague people were sick and there was a disposal there because because that because you said you know you have the multiple Ages right people young people old people the idea that the other person mentioned that was there more of a doubt more of a dominant right species that was disposing of people but just my gut is from hearing what you're saying in that description on it that's where I thought to a cemetery situations and yeah absolutely cuz I'm a colleague who does a public has a history of public health going back hundreds and thousands of years right right you might there might be an interesting connection so thank you again paleo forensics really folks who who really study what happens to bones after an individual dies and they're all these body farms you probably heard about body farms where this one in Tennessee or they just you know put bodies out and do experiments to see what happens with the body in these different situations and it's helped solve all these all these cases around the world but now we need those people to lend their expertise to something like like this exactly exactly that's a great idea that's a great I don't think we have anyone like that that's a fabulous idea thank you okay uh can you be certain the dimensions and a seven inch gap is the same today as it was a million years ago that's a great question so I am NOT a geologist I'm not trained as a geologist we have plenty of geologists and the team and their expectation was that oh no we're gonna find another route into the chamber we're gonna find that at one point there was a there was a big gap in the rock over here and everything's slid in and and that's how this all happens and they have gone through this chamber as carefully as they can there was a geologist that could squeeze through and got in there and found what he found in the chamber itself was an unbroken layer of chert all the way across the ceiling and so if there was ever another opening you it would have disturbed the chert layer and by having that undisturbed layer of chert it means the chamber itself has always been sealed to the outside and then you look around and say well what are the entry points in and that seems to be the only one is this seven inch gap now might it bit have been a little bit larger yeah the problem you run into there is if it's too large then what's stopping scavengers from getting in there and munching on all these dead bodies right so then you would have you know little jackals sniffing out these bodies and say ah you know and off they go and not only can they get the smell but there's enough light that can penetrate through that they can go down there safely so we think instead that the geologists are agreeing with this that this area was probably you know maybe not restricted to the point where was seven inches all the time maybe it was nine it was but it was never easy that that that that there was some distance between the bodies and the animals that could have disturbed that system so that the animal stayed away would also stay away was dust from the outside and so the inside was so the the folks working on the soil composition down there what they found is that it's made up of stuff from the inside of the cave so the cave itself has sort of crumbled over the years and filters down onto the floor and that's what the soil surrounding these bodies is made of if there was ever a huge opening to the outside you'd get dust storms that blow sand in you get stuff blown in and it would settle down and we've no evidence of that so it seems to have always been tough to get to that's weird it's awesome oh yeah well they're just that was actually my you were there any evidence of geological chips or geological disasters that would have moved the chamber from one area I mean it's an active area it's an active area but it's not uh it's not active like the Rift Valley in East Africa it is in East Africa you've got volcanic eruptions you've got yeah you've got shifts there on talk to tectonic plates there so things are moving and you can have these like there's sites that needs to Africa an amazing that you'll be following this layer of lake deposit and maybe there's a soil deposit underneath it and there's a volcanic layer and you're walking across and you're mapping them and you're mapping them and then they're gone it's just like where'd they go and you look up and it's oh they're up there now wow that this whole area just went cool not in South Africa it's not volcanic and so in South Africa we just have this slow trickling of slightly acidic groundwater going through the limestone and slowly dissolving in forming these caves over a long long long period of time the last three million years we think is the cave formation time but not any of these dramatic changes just to slow trickling so we're trying to date the cave itself that's key nothing can be in the cave if there's no cave so we're dating the cave itself and that's that's it yeah because you get the formation you get the stalactites and stalagmites so you can get the limestone because limestone has in a radioactive uranium from the groundwater so the groundwater comes through deposits the radioactive uranium uranium decays the lead in two different versions so where the X's cross is where your date is so that's what we're doing for the for the cave itself we're getting some interesting promising results yeah you made me think of something you talked about predators avengers' so the seven inch gap would preclude them but did you see how many evidence in the pre caves in the entrance caves of any scavengers would you find that in in some of the other caves yeah and the entries came no no entrance caves to this one that shows that they were they could smell out the yeah yeah were there like bones of any other or even scratch marks showing that they could smell this and try to get at um so I don't know if we've looked for that sort of detail or the scratch marks or something like that there are no bones from from other animals so they're no scavenger or carnivore bones in the vicinity at all other caves have them sure but not this one and you know we are so there is a team that's looking at residues in part they're looking for fire residue they're saying jeez if these things are going down into the dark zone it's gonna be dark down there if they're counting a body with them they need to be if lit the area so they're looking for fire residue and not finding much it's it's so it's an it's a huge mystery but it's a fun one it's one of those that yeah I mean you guys are asking questions you guys seem interested in it I mean can you imagine the students right you know I picked this to the students and they just you know they're so excited about it and they'll you know after class they'll come in and they'll say well maybe it's this and I'll say we have maybe and how do you test that like how would you scientifically evaluate that and they think about it and they leave and then you know three days later yeah you know Sarah's back and she's like well here's all I test it and she's getting an idea and it's awesome that's an honors thesis you know that's how we're gonna build this this I mean this is a kind of project that we're gonna be working on with Dartmouth students for decades
