On Homo naledi and the Finding Other Ancient Minds, with John Hawks, University of Wisconsin-Madison

so this is Jason alobudi and he's a grad student in Chris hittinger's lab he's the lead organizer for Darwin days this year and he's going to introduce our speaker for tonight greetings everyone my name is Jocelyn malabouti I am a PhD student here at UW-Madison and chair of our Darwin Day events welcome to all of our in-person and online attendees for tonight's session of Wednesday night at the lab which is partnered with Wisconsin Evolution for this special Darwin day seminar celebrating the enduring contributions of one of biology's most prominent thinkers and of course by that me and John Hawks [Laughter] Lauren's birthday is this Sunday February 12th but we just couldn't wait to start celebrating and I hope that some of our events might prompt some of you to have your own little Darwin Day Celebrations this weekend I want to briefly note that we have another excellent speaker lined up tomorrow earlier in the day and on Friday we have a community celebration with some free food and science Outreach activities for kids which will come culminate in an art exhibition which features participants of our Darwin day 2023 art competition more details can be found at evolution.wisc.edu Darwin Dash day I would also like to acknowledge support for our Darwin Day events from the College of agricultural and Life Sciences the College of letters and Sciences the Nelson Institute for Environmental Studies and The Graduate School of UW-Madison now for the Advent at hand it is a real privilege for me today to introduce John Hawks he is the Villas Borghese distinguished achievement professor in the department of anthropology here at UW-Madison a department he joined as an assistant professor in 2002. John engages in diverse science Outreach including an active social media presence a personal website detailing scientific advances and contributions to popular books and lecture series on evolutionary biology is also conducted extensive work on human evolution participating in projects that range from the origin of early humans all the way up to the last 10 000 years of our history as a species this includes extensive field work in Africa Asia and Europe analyzing archaeological specimens and conducting complex analyzes on genomic data from humans notably John has extensive collaborations with members of the University of whitwaterstrand in South Africa with which she has made important and compelling contributions to our understanding of human evolution but you're not here to hear me you're here to listen to the expert and so without much more Ado and I appreciate your patience with me please join me in welcoming professor John Lewis that's great thank you so much all right thank you everybody I am so excited to be here tonight um you know it's been a long time since I was here and I'm going to give you some updates on what we've been up to we have exciting things going on in the field in South Africa I'm going to focus tonight on the bigger picture how do discoveries about the behavior of ancient hominins who are very diverse how do they inform our knowledge of ourselves and our connections with those other ancient hominins that existed in the past we are truly encountering Minds that are different from our own Minds that may be shared from common ancestors with us and finding evidence of them is telling us about what those ancestors were like but also Minds that have undergone their own adaptive and evolutionary processes mindset have become different from ours in intricate and interesting ways I'm going to start as I often do by taking you into the field since I was here last we've had a number of discoveries in the rising star cave system of South Africa this one was in the news about a year ago the discovery of a skull of a child homo naledi individual that we named Letty the rising star cave system is underneath this really wonderful sort of lovely Natural Area now and if we go underground as I was this last summer we find a complex cave system with more than three kilometers of mapped passageways I want to take you virtually underground this is a part of the Cave System we're now flying past the Dragon's Back and into the Dragon's Back chamber and you're going to hear a good amount about that in a little bit the narrow passage that you see there is a Superman's crawl and as you emerge from it into a larger chamber you have to turn and climb and that climb takes you through tortuous passageways that involve a couple of ladders and some pretty narrow squeezes until you reach the upper parts of the cave system and the main entrance of the cave that we're flying past now this is just a small part of the cave system it is a beautiful underground space it's intricate in its passageways and it is challenging for our team to go through it many places there are parts of the cave system that are incredibly difficult to pass through that I cannot enter that I have incredible colleagues and collaborators who have the skills and are able to do it and it's an amazing experience to be able to be there and be part of the research as I've probably you've heard before the homo naletti Discovery began in a part of the cave system that we today call the dinleti Chamber at the far left of this image that chamber is connected to the rest of the cave system through a very narrow vertical passageway that we call the shoot that vertical passageway is about a 40-foot climb down into the dinolati subsystem of the cave as we call it now and it has a minimum width of about seven and a half inches it is a very challenging climb based on size and so it takes very specialized skills to enter this when Steve Tucker and Rick Hunter entered that space for the first time in 2013 they discovered Bones on the floor of the chamber Lee Burger my collaborator at the University of vet watersrand and National Geographic and I have described all of this in a book Almost Human this is old news at this point and so I'm going to talk about new news but let me set the context after we discovered this enormous array of Bones more than 2500 fossil fragments of homo naledi to date that we've uncovered and excavated from the cave system as we uncovered this we faced a number of interesting discoveries and a number of challenges of interpretation was very similar to us in some important ways they were upright walking they walked bipedally like we do their legs were relatively long for their body size and so we think that they were efficient long distance Walkers they were relatively skinny they stood about the height of very small bodied human populations today something like four foot six inches to five foot two inches in in females and males their body mass was approximately 40 to 50 kilograms so something like 80 to 120 pounds so they're a small bodied human in size they're walking like us but they have adaptations in their shoulders and their hands that that indicate to us that they were probably much more efficient climbers than than humans are today their hands however have morphologies that are specialized in the wrist in the fingertips and in the in the sort of flexibility of the fingers the the length of the thumb in particular that are associated in humans and Neanderthals with stone tool manufacture and so we think that they were competent tool makers in addition to being very good climbers there are many differences between their skeleton and ours that set them closer to some earlier relatives of ours relatives like Australopithecus in particular the size of their brains was about a third the size of the average human brains today they range about 450 milliliters to about 600 milliliters that's the size of very early hominins and very different from today's humans so this species was really different from us in really interesting ways we discovered over the course of a couple of years of work that the time that these hominins were deposited in this cave system was between 241 and 335 000 years ago so this species existed at around the same time as our own species was first coming into existence in the range of about 200 to 300 000 years that made them much more recent than the very early hominins that they resemble in some details Australopithecus lived in this part of South Africa before about two million years ago so this species is here at the same time as our immediate ancestors and that posed a number of challenges right what were they doing there and how did they potentially coexist with other species including our own in 2017 we announced a discovery of a second chamber in the cave system the laceti chamber that included this amazing skeleton the Neo skeleton as we named it and a number of other fossil discoveries this second chamber highlighted to us that this species was not just an accidental occurrence in one remote chamber this was a species that was actually using substantial parts of this underground space space that has not changed in its depth or in its difficulty to reach in the most distant parts of the cave since homo noleti was using the cave system since I talked with you last we had some of the homo noleti fossils here in the United States in Dallas at the Perot Museum of Nature and Science our team helped assemble an excavate and Expo an exhibition of homo naledi material that included the the Reconstruction of this beautiful skeleton reconstruction by an artist of Neo so you get an idea of what hormonality looked like from a distance and I think that in skeletal terms this is a pretty good reconstruction since I talked with you last here at Wednesday night at the lab we also have done a really amazing amount of work in visualization and understanding the scope of the cave system I want to take you on a virtual reality tour of the dinoletes subsystem of the cave you're now entering via the Chute into the part of the cave that we call the hill and a chamber you can see on the floor here right in front of us the excavation area that I'm going to talk about in a moment where we uncovered a block of fossil material of homo naledi that is that is really astounding we're flying over the excavation area and now down a steep slope further into the subsystem where we arrive at a choice of two passageways and we're about to enter into the left-hand one and squeeze along another about five meters through this very narrow passageway into the dinoletti chamber itself that chamber is a special space it's a place where homo noleti existed at one time where we've found more bones of them than we found of any other hominin except for neanderthals in an assemblage dislarge it's a remarkable space and the floor area of this still contains abundant fossil material you can see here an area that we had been Excavating in 2018 and that remains there on the floor of the chamber as we study it and try to understand its Arrangement and what it represents the lady Mela Discovery came from further yet if you go past the dinleti chamber you enter into an intricate series of fissures that as you'll see Steve Tucker here moving through them are incredibly narrow you're going to hear the word incredibly narrow for me a lot tonight right because that's a theme in this Cave System here you'll see Steve taking off his helmet so that he can squeeze through this place that's too small for his helmet to pass and continue on you'll see the light there past him it's about three meters distant and if we go further on Steve has the video now and he's recording Marina Elliott who is Excavating in this situation in a remote Fisher passage that's about 10 meters further than the dinoletti chamber where on the floor surface were bones of homo naledi we're finding bones of naletti in incredibly difficult to reach places in places that are rather difficult for us to understand in terms of how the bones Reach This Place what the behavioral interactions were that were leading the Letty to be in some of these spaces they're remarkable and they are a big challenge for us to understand here where Marina was working was where the lady Mela skull was we now have discoveries of naletti Bones from more than seven localities throughout the cave system this is an amazing array of evidence of the behavior of this fossil species we're working to understand that now one hypothesis that we're working with is the hypothesis that naletti was using these spaces for Mortuary practices that there was something special about their interaction with these deepest parts of the cave system for naletti to be so familiar with some of these very remote spaces indicates to us that they must have been using the cave system in its more easy to reach surface areas really quite a lot and so you know they must have been living there and they must have been carrying on ordinary activities in some parts of the cave system for them to be familiar enough with it to move into these very deep parts of the Cave System where they apparently carried out different activities special activities why do I say special because ordinarily when we find hominin remains inside of caves where the hominins are hanging out we find abundant evidence of their lives we find the stone tools and the refuse of tool manufacture we find the bones of animals that they were interacting with right we find evidence of their behaviors other than their bones in this context so far we're finding evidence of naletti remains including articulated parts of skeletons so we have set out during the past several years to investigate more broadly the utilization of the cave system to try to understand the behavior of this ancient species we are working to understand a cultural pattern of activity and we're doing it by probing exploring and Excavating in spaces where we have no evidence previously here you'll see marapang ramaleppa one of our exploration team working in the hill anti-chamber he's digging right here on a shelf of flowstone right at the base of the Chute as you enter into the chamber this is Becca peshado working very near where you just saw mariping and she's working on a ladder beneath her on the hillanta chamber floor I told you that there was an excavation area this is what she's working on and in 2017 our team exposed a massive assemblage of naletti fossil material that we documented and put inside a plaster jacket like a dinosaur bone and brought it out of the chute this was a major accomplishment and the team had to have enormous teamwork to do this we have since that time in the spring of 2018 been studying the contents of this block and the contents of the block are nothing short of amazing you can see abundant skeletal and dental material in this there's evidence from many parts of the body of at least two individuals it's a remarkable array of bone we're studying it with techniques that have never been applied before including right now this block is in Grenoble France where it is undergoing syncotron aided micro CT scanning which gives us a scan of the inside of this thing at Nano at micrometer resolution so it is going to be a an enormous amount of data I got to tell you but B it's going to be one of the most detailed documentations of a fossil assemblage of hominins that's ever been uncovered unfortunately that kind of work takes time and so as that develops we're continuing to work by exploring and Excavating in other parts of the cave system the dinoletti chamber in which you reach through the Chute is adjacent to a massive block called The Dragon's Back which is a narrow Ridge of rock that extends to a maximum height of about 12 meters or about 40 feet which you climb to get to the area where you can access the Dental Lady subsystem of the cave that dragons back is our access point to the dinoleti subsystem we think that it was also homo noleti's access point and our work in geology and an excavation is targeted toward understanding what the interaction of naletti with this area might have been this last year in 2022 we began an excavation in the Dragon's Back chamber it's logical that if homo noleti was accessing the deeper parts of the cave through the Dragon's Back chamber that indeed we might find evidence of homonality's activity in the Dragon's Back chamber also but we had never excavated there it was a passageway for us but we hadn't Doug to see what was underneath the surface I will say we had some pretty good reasons to think that there might be something interesting under the surface there are brechiated fossils that are in the ceilings and some low overhangs within this chamber that include bones that look like hormonality bones and so this is a pretty promising place to look for fossils and in 2022 our team assembled in July and August and began working in the Dragon's Back chamber you see here the team getting going including on the right here Sarah Johnson who's here in the crowd our graduate one of our graduate students here at the University of Wisconsin yeah give her a round of applause please Dan she sitting here listening to me say this is an incredibly challenging climb this is so difficult and when Sarah came out of the cave having done this climb she says I don't see what's so hard about that [Music] now there's some difference in dimensions between me and her that make this somehow a different kind of physical challenge and I will say that it's not only about body size it's also about climbing skill it's also about body awareness and Sarah is a climber and and she's really good at it so having her join this expedition to work in Dragon's Back was really amazing um the Dragon's Back excavation season this year was supervised by Dr kenneloy molapiani Who is our team member and collaborator at the University of waters Ronde and included two of our graduate students here from the University of Wisconsin Sarah and Erica Noble so this was an amazing get back into the field and get back into rising star kind of field season and it was rewarded with with some amazing discoveries you see the team here working in the Dragon's Back chamber um caneloy here in the front behind her Erica Noble then Janika romsawak and then Sarah there furthest in the back and we were maxing out the cave right this is about as much excavation as we could possibly do in this area sampling different parts of this this area of the cave system and in this area of the cave system beneath the surface we found abundant evidence of charcoal and Fire this is a first for us in the cave system and Lee Berger my friend announced it to the world last fall as we're exploring in this cave system and beginning to understand that this is not just a fossil space it's actually a cultural space it becomes really important for us to begin to draw the bigger picture of how fossil hominins are interacting with each other and interacting with the spaces we've begun to understand that this cave system is not only a repository for hormonality fossils it's in part created by homo naledi and that interaction the interaction of a species and its landscape in this case a Subterranean landscape the interaction of the species using technology potentially to find ways into deeper portions that's something that's very special now it takes a while for us to understand the full context of something like discoveries here chart animal bones in the previous slide you saw Hearth it takes a while for us to do the chemistry and to really understand okay how much can we really say about this what I can say is that we've found this in an area that previously we have only evidence of homo naletti's entry so from that standpoint we're working with the hypothesis that here we have some kind of interaction what we will continue to do is excavate and contextualize this kind of evidence and that will take us some time but immediately as we discovered that there's fire evidence we realized that we had to reevaluate larger parts of the cave system to try to discover what other evidence in the cave system there might be besides the fossil bones that we've found here you see Lee and um and Derek Von royen one of our exploration team members um going out the South entrance of the cave system and I'm taking the picture as we explored the cave system looking for potential cultural evidence the cave system as as I said was three kilometers underground and it's complicated I'm going to take us it's an extensive system underground and I'm going to take us in closer to the central areas where we have meletti evidence that includes the denality subsystem here and the laceti Chamber here in two different passageways areas of the Cave System our entrance to the cave that we use is here on the right as we explored the cave system we found in another chamber The Rising Star Chamber which is one of the most remote from surface entrances that we've entered so far um we found quite abundant evidence of charcoal including really distinctive chunks of charcoal scatters of Ash and animal bones in association with charcoal we cannot yet say if these animal bones are left there by naladi right there's a lot of dating and a lot of work that we have to do to understand what the context is but we're happening upon a context which is very unusual most human-used caves have scatters of lithics they have they have stone tools everywhere they have evidence of large mammal bones this is something that's looking kind of different and as we study it and probably in the upcoming year we'll be Excavating in this chamber will be working to understand what the interactions in the spaces were let me say a few words about Charles Darwin it's Darwin day at our celebration of this and the study of evolution in a biological sense really began with Darwin a lot of people read Darwin a lot of people think about Darwin and his contributions fewer people read his work on human origins The Descent of Man then read the Origin of Species his more famous work Darwin thought really hard about where humans came from and he was famously reticent to share his thoughts in public about this after the publication of the Origin of Species a lot of people know that in the origin he sort of concludes with the line that light is will be shed on man and his Origins but he doesn't shed any light it takes him another 13 years of work to get to where he's ready to share his ideas about human Origins and human evolution with the world in the meantime other people are working on this people like Thomas Huxley one of his longtime collaborators who writes man's place in nature um people like George mivart who's working on primate Evolution and trying to understand the connections of primates and Darwin is corresponding with all of these people and trying to come into an understanding of where humans fit in the natural scheme Darwin made many contributions to biology natural selection the idea of biological evolution the mechanism for evolution to me the most Central and important one is the idea that species are connected by a tree this was really an original idea of Darwin people have thought about Evolution before people had not thought about the tree of relationships of species and the innovation of the tree gives us the power to understand ancestors by studying their many descendants and to understand different stages of The evolutionary process by looking at the branches that connect at those stages Darwin famously in his notebook made this diagram of a tree the one that says I think at the top this is the most popular biology tattoo by the way I recommend it it's actually it's it's an iconic image this changed the nature of science this image Darwin did not publish very many trees and in his entire work on human Origins he published no pictures of the tree of relationships of primates or humans to them but he did think about this a lot and put in his notebooks his ideas of the relationships of species you see my transliteration of this on the right and Darwin's original Notebook on the left you see that he puts humans on the top left next to the great apes gorillas chimpanzees orangutans and Gibbons their close relatives and a branch yet further from them are the other catarine primates circapithicus macaka baboons the the circuit monkeys as we consider them today another Branch further out the new world monkeys we call the platy Rhine primates today and then further the Lemurs this is fundamentally the tree of relationships of primates as we understand it today with the exception that Darwin didn't quite get the place of humans correct Darwin like most people at the time thought that humans have a Long Branch that separates us from other great apes other closely related primates today we understand that we are among the great apes our branch is most closely related to a branch that includes chimpanzees and bonobos paniscus and troglodytes on this tree the human chimpanzee branch is related to a gorilla Branch gorilla gorilla gorilla boringi the the Western and Eastern gorillas that branch is connected to an orangutan branch which today is occupied by three living species and many fossil species here you see Pongo pygmas bornean orangutans pongoa bellies Sumatran orangutans and Pongo tapanuliensis a recently discovered species in a small area of assay in Sumatra their ancestry goes back as long as three million years ago the ancestors of today's great apes go back in time into a time when our own lineage was also diverse highly appreciate as it should be these primates were diversifying in the same time frame as our ancestors were diversifying we have an abundant record of human Origins this is at the Smithsonian a wall of skulls right where you see I think more than 150 different skulls of fossil hominids from the beginnings of our lineage more than six million years ago up until the recent past it's an enormous array and it's full of skulls there are relatively fewer complete or partial skeletons of things but there are some impressive ones and as we go closer and closer to the present we find partial skeletons of Neanderthals and more recent modern forms of humans we have abundant skeletal evidence of our evolutionary history if I look at some of that evidence I've put up here as sort of my own wall of skulls this is not super representative except in so far as I've tried to put a skull up here for a number of species and you'll see 17 of them and if we look at these skulls and their arrangement we can make a tree very much along the lines that Darwin might have made where we have species like our own at the far right and species that are close on the tree to us that lived in the past that are now extinct and as we go further left species that are progressively more and more distant from us in terms of their common ancestry on the tree if we look at that left most part of the tree and consider the kinds of hominins that were there we see hominins that belong to Genera called Australopithecus and paranthropus Genera that are today extinct and have been extinct in the case of paranthropists for more than 800 000 years in the case of Australopithecus for nearly two million years um these were diverse and they lived for millions of years today they're gone but one branch of them survived and that Branch after two million years ago also Diversified that Branch includes all of the extinct species that we consider to be members of our own genus the genus homo you see here a wide array of them humans again on the farthest right surrounded by other humans that are kind of like us in some really important ways humans that we today call the Neanderthals or archaic humans we see extinct species like Homo erectus and extinct species homo naledi has its place on this tree earlier extinct species like homo Rudolph Francis Homo habilis these represent ancient diversity that once existed that our own Branch evolved from and that we have survived our origin Was An Origin that was not alone It Was An Origin that was among many others and those others had their own ways of living their own ways of thinking their own ways of being we've recently gotten a lot more evidence about these relationships from genetics and it would be wrong for me to talk about the tree without showing you a genetic tree DNA evidence goes back only in the maximum case in humans so far around 430 000 years we have DNA from an early population of Neanderthals from SEMA de los Hue so Spain that is that age so we know something about neanderthals we know something about other kinds of hominins including a fossil population called the denisovans discovered initially from this tiny piece of a finger bone from denisova cave in Siberia today we understand that this was a diverse branch of ancient hominins that lived alongside neanderthals and our own species probably in the eastern and Southeastern parts of Asia and we understand that today's people and these ancient people had interactions with others others that we have Echoes of in the DNA that survived so those others we cannot yet identify with fossil evidence we have genetic fossils in this sense the Denise events are a great example of that initially found from a finger bone today we still do not have a skull that I can show you the face of that we know to be Associated genetically with this population we do have a jaw and so there's something and we will have more is almost certain we're going to have more as we go further back in the past we discover that these lineages interacted with each other they mixed with each other and they mixed with others our tree was a tree in which our species originated among others and those others did not just form part of the scenery those others were interacting with and interbreeding with in some cases each other we come from a tree with hybridization that means that these different species interacted and they interacted through cultures now as we look at this tree and see the diversity of hominins that are part of it and understand that they each had their way of living they each had their time they each had their place and they mixed with each other we can start to assemble a timeline to try to understand their interactions here we see humans at the far right again that's the present day and there's a density of evidence of these other kinds of species coexisting with our species at various places we see that there's neanderthals at the top and archaic humans from from East Asia next to them there's modern humans and archaic humans from Africa there's homo naledi that coexists with early modern humans and there's the very small bodied species from Indonesia homo floresiensis that also persists until 65 000 years ago as we Trace our Branch earlier in time there are other times that we see many species coexisting these interactions among these species must have mattered to our ancestors they formed a part of what made us human now I'm very concerned now with understanding their behavior how did these ancient hominins interact what was their way of living what were their minds like when the title of this talk went out on Twitter people sort of kicked back at me they're like mimes what are you talking about minds you're this is fossils this is archeology we're not looking at Minds minds are our way of experiencing the world they're also our only way of connecting that experience to the world itself minds are our interface with the world around us that means that they're also our interface to the other individuals in the world around us and the interface to the other species that existed in the world in the past when we look at the brains of ancient hominins we're not looking at Minds it's a challenge for us scientifically to try to connect those things with each other with evidence here you see exceptional endocast natural casts formed inside of skulls we can study the insides of skulls we look at them we get a lot of them an obvious one that I pointed out earlier is that homo naledis brain size is about the third the size of the other hominins that coexisted in Africa at the same time that includes our own species Homo sapiens and archaic forms of humans sometimes called homo rhodesiansis these crania all date to the same time they're very different from each other in size an important question is what difference does that make to behavior we know a lot about the evolution of the size of the brain this is endocrineal volume how big the inside of the skull is over time over the last four million years in hominins I'm going to parse this out a bit because there's a lot of data here and that data actually is chunky when you look at the details if we look within Africa here's the trajectory earlier hominins before 2 million years ago all have brains around 500 cubic centimeters or so after that time some hominins get bigger braids but not all in Africa you can see that there's later hominins including homo naledi that retain that ancestral smaller brain size or evolve convergently with earlier hominins toward a smaller brain size if I stretch out the last two million years and look at that time frame you'll see that there are individuals of homo erectus throughout this time that approach homo naletti's brain size small brain size is something that exists across a long span of time we're used to thinking of our species as having been the end of a trajectory where that trajectory is toward larger and larger brains it's actually not the case the case here you see archaic forms of humans like homo rhodesiansis compared to living modern humans and our immediate fossil ancestors they're a little different from each other if we look at evidence from Southeast Asia and East Asia you can see that erectus then there's these archaic humans and they're big in brain size and then modern humans are a little smaller neanderthals pick up in Europe after about 430 000 years ago and modern humans immediately follow them this starts to look kind of chunky it starts to look like groups homo floresiensis persists in Southeast Asia so as we look at the overall tree of the last two million years of evolution we see that there's a pattern of diversification hominins are becoming different those hominins are all classified within our genus they all share common ancestors with us around two to two and a half million years ago they're part of the same tree but this is a tree that's becoming diverse in its brain size and as you've seen a hint of with homonality it's becoming diverse in strategies for interacting with the landscape so going back to this tree we're not going to try to understand the whole organism how are these species interacting well there's other things to the brain besides its size this is evidence of the insides of the skulls of homo naledi brains we've studied these and in a paper in 2018 our team showed that the frontal lobe of naletti's brain actually is very human-like in its organization it's different from earlier hominins that had smaller Brains it's actually human in this respect there's a structural aspect to our brains that is shared with a species like naletti despite the fact that there's a big size difference in the brains that may mean something very important this part of the brain in humans the the left frontal lobe is essential to forming language syntactic language making sentences that make sense we don't know whether that would have been true in ancestral hominins we cannot see their forms of communication directly we have only a little bit of evidence about the vocal tract in some forms of hominins and it does suggest that homo shares a vocalization capacity with humans whether it shared a linguistic capacity or not is unclear when we think of what big brains are for there's been a lot of scenarios a lot of hypotheses about this and technology is maybe one of the most widely known these Stone points which were halfted onto Spears come from KATU pan in southern Africa about 500 000 to 300 000 years ago this is the archaeological evidence that occurs in the area where we find homonality we don't know whether this evidence was produced by naletti or whether it's produced by other forms of hominins that may have also existed at the same time in the same place we know that our immediate ancestors in this time frame existed and they could well have been here there's also chunks of ocher a mineral pigment that you can see the engraved lines on right these are made from rubbing the ocher onto hard surfaces we have other chunks of ocher that looked like they were rubbed on soft surfaces in southern Africa we don't have fossil remains in direct association with archeology like this we haven't yet found archeology like this in the rising star cave for example in North Africa however there are very similar archaeological forms and they are found in cave layers with early members of our own species homo sapiens in East Africa at alargo Sile this is famous site that is this littered with hand axes that you can go as a tourist and walk on the walkway and see the hand ax floor there those hand axes are around a million years old and they're they are found on the same landscape as this fossil skull which is very similar to a niletti's skull this was once classified as Homo erectus today I would say we don't know for sure but there are also pigments that allergicily in a younger time frame around 300 000 to 400 000 years old pigment use incision of lines becomes characteristic on pigments after around a hundred thousand years ago those are the things that people look at and say maybe brains are doing this right maybe this is what communication takes a form technology takes a form that requires Innovation from big brains people used to say that neanderthals would have been incapable of this kind of thing Neanderthals have very big brains their brain sizes are human in their size over the last two decades a revolution and understanding of the behavioral evidence of Neanderthals has happened neanderthals primarily a western Eurasian fossil population here's a skeleton of a neanderthal that has a hyoid bone that has a shows a human-like vocal tract the evidence of Neanderthals as we've poured over it over the years these fossil fragments from croppina in Croatia where I'm going to be in a few weeks this is my friend the late uh jakov radovich who used to curate The Collection um those fossil fragments as we've studied them we've uncovered evidence of incised lines on the frontal bone of one of these my friend devorka radovich who is yaakov's daughter and presently the curator of this collection identified eagle talons that have evidence of where they were strung together this engraving on the floor of gorham's cave in Gibraltar more than 60 000 years old made by Neanderthals in addition pigment spots in various caves in Spain and Southern France appear to be Neanderthal in manufacture and Neanderthals abundantly interacted with pigments and in a deep cave in France called brunikel they constructed a circle out of stalagmites hominins are experiencing their worlds and altering them they're going into spaces that other species don't access and they're making things that are different they're marking their environments and they're marking themselves now many people look at this kind of evidence and think wow you know this is what humans do so therefore they must be human that's a kind of a chauvinistic point of view and there's nowhere that's better evidence for this than southeast Asia where on the island of Flores separated from the Asian mainland Always by a permanent water crossing even at lowest levels of sea level there are hominins that are very different from us brains that are around 420 cubic centimeters in size smaller than theletes skeletons that are smaller than theletes this species homophoresiensis evolved on an island or reached this island by crossing over permanent water straights you may say well okay that that could happen that seems like a an amazing thing um they make stone artifacts that are very interesting not necessarily super complex although these blades are beautifully manufactured from Liang block cave where the skeleton that I just showed you was found from mataminge these artifacts more than 800 000 years old indicate flores's presence on the island at that date but floresiensis is not alone on the island of Luzon in the Philippines is another small bodied and small toast species that existed up until the last hundred thousand years this species discovered in 2018 named homo luzonensis we don't have a skeleton of with a with a skull that we can say the brain size of so we can't say for sure whether this was like fluoresensis but it looks like floresiensis these are species that are crossing water their capable of colonizing new places living in New ecologies and doing so with very different biological equipment than we're used to having they're doing it with small bodies and small brains and they're doing it not a hundred thousand years ago not three hundred thousand years ago they're doing it eight hundred to a million 800 000 to a million years ago that kind of Behavioral complexity is evidenced in the material record at wonderwork Cave in South Africa some of the earliest evidence of charcoal and Fire vastly older than the evidence that we found in the rising star Cave System indicates that hominins are interacting with fire going way backyakov in Israel is an open air site it's not a cave site it's by the Jordan River and in this site there are hearths where ancient people 800 000 years ago roasted pistachios another thing people say brains are for is social behavior and there's a deep reality to this Hanuman language are well known for their coalitions that they form between males to compete to displace dominant males within a group that kind of ability to ramp on and ramp off aggression in very intricate social contexts something called Machiavellian intelligence is something that many scientists think brain size has evolved for grooming getting along with other individuals affiliating with them something that people think this is what brain size is really for mountain gorillas this is a male mountain gorilla who's affiliating with and and taking care of this young juvenile that kind of social behavior is something that we use our minds for right these are primate Minds I put this slide up here to remind everyone that I'm going to show a disturbing slide next that includes a dead gorilla so if that's something that that you don't want to look at I want to alert you to it because the other side of affiliation the other side of Machiavellian intelligence the other side of aggression is grief and Mourning here's a gorilla morning his mother we find this in the fossil record also at SEMA de los huesos in Spain the single largest accumulation of fossil evidence of any hominin more than 30 individuals of an early Neanderthal population representing a group of some kind in a pit with their bones tossed in probably originally as bodies many of them the victims of aggressive or violent deaths but as evidenced by perimortem wounds on their crania and other parts of their bodies an intentional Act of some kind deep in a cave homo antecessor also in the attapuerca mountain around 780 000 years ago cannibalized groups are interacting with each other in violent ways in aggressive ways and also in many cases in caring ways in ways that manifest the emotion of grief when I look at the remains of homo naledi that we're working on in the rising star cave system this is what I want to try to understand what do these remains tell us about the interactions of the hominins of the individuals and we are learning that so as we look across the tree we're seeing that there are different experiences and those experiences we have fragments of evidence of our field encounters more evidence every year and we find new ways to analyze it what I'm telling you about tonight includes evidence from around the world that didn't exist five years ago very little of this stuff existed 15 years ago we're making rapid advances in understanding the lives and cultures of ancient hominids and as we make those advances we experience Joy but we think about the the emotions and the joy that the ancient people also experienced this is where our emotions came from this is where our minds came from so I'll leave you with homo naledi I think about it a lot and you saw the Reconstruction earlier that was very human-like in its look and John Gertie who's a good friend of mine a Paleo artist has a reconstruction that is a little bit edgier we have our ways of looking at the past and bringing to it something different from our own experience it's a challenge for us as scientists to try to go beyond our own minds and understand the minds of others but it is so essential because our minds came from them the tree that connects us is the tree that will tell us how our minds originated with that I'll end and thank you all for coming I'll be happy to take questions afterwards but um but before I do that I just want to say I really appreciate you all coming out tonight it is amazing to be back in person here in Madison and giving talks and I'm really happy that's happening again so thank you all and uh and I'll be looking forward to coming back again and giving you the next installment foreign we're waiting for the mic so that this could be recorded the questions right so but after you guys ask questions I'll also repeat the question yeah you had a question in the front yeah we'll let you get the mic it's a little bit cumbersome but it does let the The Voice get recorded given the cave system and you've got a lot of electric lights there what what concerned me is how did the homologie navigate these complex caves without any light because it's I'm sure it's extremely dark in there yes exactly the question is how did naletti navigate these cave systems without light one answer is they had fire they were clearly making fires and using the fires to see in distances that they couldn't have done without the fire but we think also that their ability to navigate underground was very impressive you know they clearly were familiar with large parts of the cave system we think that probably that this was partially tactile that they learned places by feel I think and I'll say this is partly speculation I think that this was also social nobody ever did this alone they were doing it as a group children adults of all ages some that knew the cave system very well and some that were experiencing it for the first time and that kind of social activity is highly tactile so if you ask me how do I think this was happening I think that they were going to the edge of what they knew and they built a fire there and that extended what they could see a little farther and they learned more and over decades maybe over centuries they came to inhabit this space in a real way all right next yeah but if they were using fire for light to access these deeper parts of the cave why didn't you find any charcoal Parts I I just showed you the charcoal in the Deep parts oh so so in the denality chamber in particular right why isn't there any charcoal there you saw the space that we've dug it's a very minimal excavation I think that is something that that maybe a lot of people don't understand um why don't we find everything that existed all at once in the early 1900s it was very routine for archaeologists to go into a cave maybe like this and bring in a large team of workmen and carry out everything in buckets and baskets and take the entire contents of the cave out in the early days of archeology this was in the service of finding good artifacts that they could sell and the amount of evidence that once existed in cave systems in Europe that was flushed away buried out of context with back dirt or run down Rivers as they sieved the sediments right today we use every teaspoonful of sediments out of cave systems like this to sample for DNA which gives us evidence of all the species that interacted above the space and that were carried into the cave right we're getting evidence of hybrids from Tiny flakes of bone like this our ability to bring evidence out of tiny things is vastly grown as a consequence our caution about digging has vastly grown we now dig in a very very controlled way with relatively small excavation units and sometimes we find really incredible things the Dragon's Back chamber we've found really cool little charcoal and little cool hearths it's amazing but if those happen to be four centimeters to the left we would have missed them so our our sampling of this is very sparse at this stage the age of the theletting material that we've dated in the dentality chamber is between 241 and 335 000 years ago we do not have dates on much of the other naletti material throughout the cave system we don't know how long a duration this was and we don't know whether this was a group or a sustained occupation or episodic occupations over potentially tens of thousands of years yep I have a question about the logistics like how long does it take you to get from the cave to the dragon from the dragon down the Chute into the the denalati chamber or whatever and yeah do you need to stay there overnight sometimes or that sort of thing the logistics vary based on the part of the Cave System um right now the route from our entrance and the command center where we set up our equipment to monitor the excavation into the Dragon's Back chamber is pretty quick our team can do this in five minutes um we don't tend to do it in five minutes we tend to take some a little bit longer time but it's not super distant from there up the Dragon's Back requires uh for our team for safety purposes it requires us to harness and use stable fixed ropes to climb that process takes a bit longer um our you know in an emergency our team members the exploration team could get to the top of dragons back within 15 minutes but for routine climbing this is about a 20 minute sort of from the entrance of the cave up dragons back is it's going pretty fast down the Chute is a one of the time process for us and takes some time for people some people do it really quickly and some people take quite a lot longer um my friend Lee lost 50 pounds this last year in order to do this journey himself and it made some remarkable discoveries in the chamber that will be actually talking about on Netflix this coming May or June so if you get Netflix watch out for that we're going to have a film documentary that's that's broadcast on that um but that claim for him took an hour and a half to exit the chamber so it can be very long routinely working from start of day to in place ready to work in dinaletti if we were Excavating there is about a 45 minute commute mm-hmm yes the homologie fossils are dated in the 200 000 to 300 000 year range were you and your colleagues perhaps secretly hoping for something a little more electrifying like say 10 000 years old so that's a great question and it's one that that you were I think you're possibly the first to ask most people who ask about the date ask did you wish that it was older so it could be the missing link right in fact finding something that is unexpected is exciting for us no matter what it is but your question what if they were here very recently right what if this was a species on the landscape with recent humans there's nothing impossible about that and that's something that we think about a lot because if this species was well adapted to its psychology and interacting with early hunter-gatherers there's no reason why it could not have persisted there's nothing that would have made it go extinct until you know agricultural humans show up and so if you ask what do I think the likelihood is that some populations of naletti may have persisted into that kind of time frame right the Holocene I would say I would not bet against it do I wish that we'd found it I don't know you know it raises problems to find something like that because it immediately creates you know different kinds of questions about interactions but those are questions that in the hominin fossil record we have abundant evidence of of interactions now I think that we have to start thinking about interactions in new and more interesting ways and that's a very interactive way of thinking right that's not just biology it's biology mixed with culture the social sciences psychology and I think it's exciting but it does it will create conversations that are very interesting uh yeah I was wondering if you have any guesses as to how big the habitat for hormonality would have been if you know during that period of time and also what kind of numbers that I would have represented to create a separate species yeah that's a great question right what was it not his ecology right where did it live when we look at species that are coexisting in the African landscape and this is true everywhere right but but I'm pretty familiar with African landscapes when you look at species that are existing you tend to think there has to be some ecological difference that enables two species to coexist you know they have to be depending on different resources they have to be living in different ways and it's tempting to go back to the fossil record and say that has to be true noleti has to have been doing something different from Homo sapiens or else they would have competed and one would have gone extinct what we don't know is what key difference there might have been the environment around this the Cradle of humankind area 250 000 years ago was fundamentally similar to that environment today there were some periods where there's a little more water and some periods where there's a little less but it's basically High grassland in the same way that it is now that ecology exists across most of the spine from South Africa up through the borders of the rift valley into Ethiopia so if that was the ecology the ecology is very widespread species that exist today across City ecology often have hinge points between either sister species or different you know subspecies within species across Tanzania or basically in the equatorial area and that could have been true in the past it could have been that there's an encounter between two different populations or or you know multiple populations at the moment this is a matter for speculation until we have additional fossil evidence we are not going to know what how potentially widespread they may have been we also won't know what the critical factors are one big gradient in Africa between animals today is disease another big gradient has to do with parasites another gradient has to do with different food types in terms of sour grass versus sweet grass when you look at grassland a lot depends on the underlying geology in terms of what can Thrive there and those are not so obvious to the eye so if I ask what habitats would naletti have been in I don't know yet what to expect is important for them if you ask me to speculate I'd say the biggest Factor that in human history and prehistory that mattered was disease and I tend to think that maybe noleti had some tricks in its immune system that our species hasn't had and maybe vice versa but that is really invisible on landscapes that's something that's very difficult to try to see and it could be something like that do you find any evidence of any of language or or a cave art like in France anything like that in this environment that you're working in and secondly what happens is there's a medical emergency for somebody's way the hell down in a skinny little hole yeah what do you how do you how do you deal with something like that without causing some destruction to get the person out I'll take that question first because it's an important one right we you know a lot of people ask us why don't we make the cave easier to go through and we have at various stages now altered parts of the cave that are unnecessarily difficult that pose the safety issues for no purpose when we have evidence that the cave you know sediments in the cave are not you know are more recent than the Letty or something like that the Superman's crawl is an example of this the sediments are later than the Letty and we're not changing our evidence about naledi by altering the form of that of that particular passage and that has created a safety issue for us and so we've altered it enough to make it easier to pass that's one reason why you see me at the top of the top of Dragon's Back it's become safer for for someone like me and so I'm able to get into places that I wasn't before um with the passage into dinoletti there's an incredible difficulty getting somebody out of that if they were to be injured we have been fortunate that we have not had injuries on site that have compromised people's ability to climb and and get out of that chamber um I will tell you that we go through a training process and are very rigorous about people who are able to access those spaces and they do so only with our team of explorers who are among the most experienced cavers and Climbers on planet Earth right now we have one of the rare teams of professional cave explorers and they train and are fully certified in safety and maintain those certifications annually so you know they're among the best and we don't travel into these spaces without them but that being said it is always possible that some injury might happen that would create a problem in that event I have to tell you that our contingency plan is to keep that person safely in the space bring medical staff into the space and keep them there until they can climb out for weeks or months if necessary so it is not trivial the risks that people take and that being said the University's insurers are listening to me um that being said we're working with fixed ropes we're working with people who are highly trained and we're working on routes that are highly explored so it's not like mountaineering where you're free climbing or you're doing something new and different you know this is something that's that's that is as safe as it can be made and and that you know is is a testament to the professionalism of the people that we work with your other question is there any kind of trace of markings or or you know paintings or some kind of physical interaction with the cave environment I can tell you that we are investigating that very intensely and um I would say watch for the next installment of this because because when I say that you know homo naledi was interacting with its environment I mean that we're now looking for things that we weren't looking for before and this cave is yielding discoveries that we didn't expect to find thank you yeah it was just uh Curious uh first of all uh how what is the linear distance from the first entrance to the uh second entrance that you showed what is the difference in altitude between the first entrance and the second one and on on top of the previous question is there a very sophisticated uh Cave rescue uh organization in South Africa like there would be in most parts of the U.S that's a great question yeah thank you for asking that um the distance from our cave entrance to the top of the Chute is about 140 meters and and then down the Chute is about a a 12 meter drop that the floor of the dinner lady subsystem is about 35 meters below the present surface um so the total descent is a little it's not quite that much because our entrance is on a hill and uh and the hilltop is is the measure but we're descending something like 25 to 30 meters that descent involves about a 15 meter climb in the middle of it um and it's about 140 meters through the laceti chamber where we've also excavated and we have you know the discovery of the neoskeleton is about 80 meters in a different direction into the cave system and about a similar distance under the present surface about 30 meters Underground The Rising Star Chamber where I showed you the charcoal and bones that is a little bit harder um it's uh you guys are hearing me say that's a little bit harder as if um that is probably 150 meters or more to the nearest entrance and it's circuitous so I haven't measured the it's not the crow flies but as you actually have to go it's longer than that it's probably more than 200. we do have naletti bone material from a locality that is more than 500 meters into the cave system and I can tell you that it's in an area where we think that probably in the past it was excess through a different route than we used today so I'm not saying that naletti was going 500 meters into this but for our team this is a place where if we excavated there we would camp out we would stay there the cave rescue is an excellent question in fact there is a highly professional cave and and climbing Rescue Unit that is in this part of of South Africa our caving team has many members of that Rescue Unit and so when they're not on duty you know working in the cave some of them are actually working to save people who are climbing on the high mountains around um cave rescues themselves are relatively rare but but do happen in this part of South Africa in the past there are places where there's K where there's underwater access and people have died in underwater cave exploration in this part of South Africa so it's something that people take very seriously but there's a very professional Rescue Unit that our team is deeply embedded in you know cave diving is the most risky type of spelunking yes we're our team is not looking to do any underwater exploration in this area I will say that some of the Amazing Discoveries that that you know I can share with you in Europe have happened in places that are accessible today only by diving um so those next phases of exploration actually are yielding new discoveries and some of the newest and most exciting things including some of the earliest North American archaeological evidences from caves that that people have dived into you mentioned the idea of keeping in touch as people go through the cave system can you tell us about the Acoustics of what it's like to be in the cave with the idea that they'd be using voice to keep in touch I think it's quite amazing if people ask how do we stay in touch we have the internet now we have Wi-Fi in the cave these guys are digging down there in their phones and they're you know it's when we started this it wasn't that we had to run wires and we had security cameras that could see in the dark and it was just awful we have a hard line telephone that we communicate deep into dinoletti that is our backup in the event that the internet goes down because it does you guys may know that South Africa is having periodic power outages that are called load shedding there in North America we would call these rolling brownouts and so most people are going multiple hours a day without electricity and in the cave system that's something that we have to Grapple with and we have backup generator units when we need them but but that is an issue if you ask how did naletti communicate in this situation there's a lot of speculation at hand but I can talk about acoustics if you yell in the cave it's surprising how little distance your voice carries your voice really deadens really fast in these spaces and you know these guys working in Dragon's Back for instance if you're coming through the Superman's crawl you're not going to hear them until you actually enter into the chamber it is really you know when people enter into the cave system and start their descent from the entrance of the cave you stop hearing them after they're gone maybe 20 30 meters just dead so voice doesn't carry real far what I have found and this is interesting to me and I don't know yet what to make of it is that if you tap on something if you bang on something it carries a long ways that kind of sound actually carries quite a long ways and so I think but this is again total speculation that I imagine an environment with a species Underground when they're in the cave and when they want to make themselves known they're going to bang on something and they will be heard and it must have been cacophonous when they were doing that so it's fascinating because the voice doesn't carry in that way I think it's it's a different it's a different auditory environment and that's something that must have that they must have experienced I got a I got a question about one of your slides there about halfway along the talk you had four million years at the bottom and a whole bunch of skulls that you thought were interacting at the same time yep am I imagining or is that like there is a curiosity there so there's a whole bunch of skulls in one era and then there's lull I think you're asking a really you're asking in many ways the right question right which is that this isn't you know this isn't a random array it doesn't it doesn't look random it looks like there's some kind of pulse and some kind of pulse at two million years your question is this real or is it some kind of artifact of the data is one that we can't answer yet and just to give you an example I'm going to go back to this slide with the brain sizes this is our evidence of skulls in Europe and Western Asia where we can measure the size of the brain you'll notice that there's something missing and it is skulls from 1.8 million years ago to 430 000 years ago there's a couple of cranial specimens in that time frame that if you were clever they're broken and fragmented if you were clever you might put a dot on here but it's still a big gap and that is actually I think part of what's going on with with that pulse appearance there are times when there's just no evidence in some parts of the world or there's very little and in Europe that may be because there were times that hominins weren't there they may have been not there it may be because our archaeological discoveries are not a representative sample it's a great question you know do I think that disease is a factor or do I think that you know species Replacements are a factor ecological interactions are a factor the I can only add two things about that one is in Europe and Western Asia we have ice ages and so there are geological changes and they do matter and that might actually drive some of this um the other is that six hundred thousand years ago neanderthals and denisovans show up they diverge from our African ancestors that that that are common ancestors with them and they spread very quickly into Eurasia and they Diversified Neanderthal and denisovan presumably West and East and that means that they invaded space that other hominins were already in and for some time they might have coexisted with those other hominins we may have some fossil specimens that suggest coexistence or maybe not but those species found a new trick and they spread quickly that was an event what caused that event I would be hesitant to speculate right we've had 150 years of speculation about why modern humans came and replaced the Neanderthals and now we know that modern humans came and interbred with the Neanderthals and we're all part neanderthal so all of the speculation about what happened was misguided I don't know what happened in the earlier instance and I don't know how many other earlier instances there might have been that's on the horizon for us and I think that before my lifetime is over I think we're going to know some of these things because we're going to have DNA data or protein data that tells us some of it we're already getting protein data on some of these earlier hominids yeah so a straightforward question is how long did they was their average lifespan and then a more speculative one there was a great paper for a novice called the cultural Wealth of Nations in 2004 in nature about the genetic boundaries in Europe that were tied to of course physical boundaries but also cultural boundaries based on language so the hybrids that you're playing with are intriguing about why they would be hybrids because they probably had the same rules we do mate with who you could speak with I think that to take that ladder Point first I think that's absolutely what's going on right we're you know I deal with geneticists who look at hybrids and they're like oh my gosh the data right there literally is a hybrid individual from Denise of a cave who has a neanderthal chromosome and a denisovan chromosome for every chromosome he had a neanderthal mother and a Denis even father and by gosh first generation hybrid and the Denise even father has little Neanderthal pieces in his chromosomes right so we know that he came from a mixed ancestry and that's true of some other Neanderthal and Denise of an individuals we can see that hybridization that's happened in multiple phases to take that to where you've just asked species don't hybridize unless they can interact unless they're mating practices are familiar enough to each other that mating happens if we look at recent humans we don't talk about hybrids right we're all one species I don't know that that wasn't the case with neanderthals and denisovas I know that they're genetically more different from us than we are from each other but I don't know that that difference is so much that there was any kind of genetic issue with them interbreeding what there was was a lot of space and thin on the ground people and these populations may not have encountered each other very often right we're not looking at a landscape like Bronze Age Europe we're looking at a landscape that is sparser inhabited than anywhere that you've been including Siberia today right this is very sparse where there would have been pockets of people pockets of families we have some genetic evidence about that structure we have sites where neanderthals we can see the kin in the site and you can see fathers and daughters and you can see the level of inbreeding in their genetics right you see relatives so we know that their group structure was affected by that larger scale population structure in that setting I cannot imagine that they would have encountered some other people who might have looked a little different from them and not thought oh yeah a new kid has moved to town right but it does raise this issue of cultural interaction right our mating practices our interactions with each other are conditioned on cultures they're not always happy right I don't want to say that you had to have some sort of cultural alignment because we know many historic examples where it has not been happy where there's been tremendous exploitation where there's been rape where there's been Warfare and children have resulted and so I imagine that in the Deep past sometimes people loved each other sometimes they hated each other sometimes they fought with each other sometimes they felt grief and it was just like us in those emotional standpoints right the finer points right could they form a sentence that was better than chat GPT I can't answer that right I haven't asked why haven't we done this yet chat GPT write an essay with Neanderthal language the lifespan we think that there this is actually partly speculation we have an old individual whose teeth have worn mostly out we don't have an age for that individual yet I think in the end we may because we may be able to do epigenetics and get some sort of lifespan estimate but we don't have that presently our thinking about fossil species like this is that their teeth were worn out in their 40s and 50s and their development might have gone a little bit faster than ours but in fact naletti is interesting because their canines are early erupting relative to earlier hominins like Australopithecus or even Homo erectus they have a human-like Dental sequence and that's pretty cool because it means that despite their small brain size they're having some sort of extended period of maturation we have a question on Zoom yeah to what extent were environments and climates during the periods when the various species were living inform your efforts to understand their culture I think that climate is Central in some instances and is peripheral in others one challenge that we face is that as we go far enough back in the past and by far enough really before 120 000 years ago 120 000 years ago was the last interglacial the last climate Optimum the time that was very much like today in terms of its climate it was a time when glaciers were not covering the northern continents and the sea levels were high and there was you know amazing fertile forest and land across much of the temperate region of Eurasia and Neanderthals had their Heyday that was a great time for neanderthals we know that climate matter to them because they expanded into new places and they became successful there and they were hunting vast large animals they're hunting rhinoceros and elephants and they're doing great stuff before that we Face the challenge that although the climate Cycles are well known our ability to estimate the ages of things gets worse and worse by the time we get to 200 000 years ago when we're dealing with noleti when I say that niletti's bones are between 241 000 and 200 and 335 000 years ago that sounds very precise right that sounds good 241 sounds very precise in fact we know very precisely the age of the rock that we found on top and we have an upper limit which is actually not very precise on the interaction of their teeth with the natural radiation inside the from the groundwater that is causing a buildup of electrons with the wrong spin so we have an upper limit based on that so our limits are kind of precise but those limits are far apart that span covers an entire span of highest glaciation to warmest climate if you ask me what was the climate like when naletti lived I'd say well here's what I think the extremes were in South Africa and it could have lived in any of these because we don't know as we go to these more ancient species that's the situation that we're in with climate if you ask what was the climate that homo floresiensis lived in like I would say we know that today's climate in this part of the world Cycles between el Nino you know La Nina years and and other years and so there's an extreme of rainfall and extreme of of seasonality and temperature but it's a pretty moderated climate and I'll say the same thing about the past but it doesn't tell me something that's especially helpful so while I think that climate was super important I have very little ability to tie hominins to it before about 120 000 years ago good just another mundane question again how do how do you deal with hygiene personal hygiene you can't have porta potties down there if way down the depths what do you do well um I should let Sarah answer this I'm back out from Dragon's Back it's not such a problem we have latrine we have you know sort of porta-jons and and if you come out of the cave from dinoletti this is a bit of a problem um we tend to in the deeper parts of the cave when people are working there we tend to time our work and time our eating and snacks and so on so that people can go when they are finished with their shift so that means that we tend to spend about five hours six hours working underground and that's about long enough um there are um there are designated areas um and and Facilities that are available in the event of an emergency um but but the team really tries not to not to use them yeah um my question is when I had heard these lectures before one of the things that was surprising I think to you and the other uh archaeologists was the um was the the variation of of human-like versus ape-like body structures have you come to a conclusion about an understanding of how come things aren't as linear as I had expected that your field would have thought before they saw homolody I think it's a great question one of the one of the challenges that our field faced was that much of our evidence right I showed you that beautiful wall from the Smithsonian right with all those skulls much of our evidence has that kind of form it is you know the beautiful things I'm just going to scroll back to them because they are beautiful the beautiful things are skulls and for the rest of the skeleton we tend to find pieces of things we don't often find what comes up in the next slide skeletons that connect lots of parts with each other we know a tremendous amount about the human skeleton chimpanzee bonobo skeletons gorilla skeletons right we know living skeletons really well we know a tremendous amount about Neanderthals I've showed you a couple of the sites where we have thousands of Bones we know a lot about Neanderthals Homo erectus we have one skeleton one there he is turkana boy that's one of the best known fossil species and we have one the number of homo erectus hand bones you see that there are three hand bones four hand bones there on turkana boy in addition to those four there is one wrist bone from yokochian China that is the record of hand bones for Homo erectus we have now presently more than 180 hand Bones from homo noleti from must be at least a dozen individuals at this stage with hand bones so one issue that has happened in our field is as we've made discoveries like the niletti discovery and these sadiba skeletons on the right the Little Foot Discovery right those are all discoveries that have been announced within the last 10 years and have been published and available for study for the most part for less than five it's an amazing growth of evidence about the whole body now you might understand that when you only had pieces of bones that weren't connected to the same individual's skull or teeth you might think I'm going to connect these as efficiently as possible and that's what people tended to do when you find more complete evidence you discover that oh the line isn't the shortest line is not actually the path that this took it took some sort of more complicated line and that's what we're encountering it's really just about the growth of certain kinds of associated evidence why did it happen this way is a really great question because what it does for us is it fundamentally challenges our notion of how we evolved we've been thinking about Evolution as efficient the brain size thing it takes a gradual shortest route but when you actually look at the details and say wait no this is big here and small there and there's this small thing with the big thing and at the time that these small things existed some of them were were sort of doing something different you start to realize that this isn't simple at all it only looked simple because we had so little evidence it's a natural process of science to take the evidence you have and come up with the simplest idea that's what we want our scientists to do that's what we're training our students to do come up with the simplest idea but it's unrealistic to think that in a historical science like ours that the simplest idea is what happened and as we find more evidence we discover that oh some things were simple but a lot of it was not and if we look at it from a different perspective if we actually put this evidence together in a different way maybe it would be simpler to think of some other thing even if it made this first bit of stuff look more complicated that's where we are now we're just coming up with new ways of thinking um earlier in your talk you said in passing at the beginning something about the thumb bone or the the thumb of um and uh now now I guess there's two questions that sort of made me think if you're talking about you thought that they navigated Maybe through some tactile methodism of the light which kind of made me think about that but in addition now you're you're talking about the fossil record and how incredibly Richard is here and how weak it is um I I thought you were saying that it was distinctive or different so I guess that's sort of a follow-up question to like what is distinctive or different how do you know it's distinctive and different if you have we have such little evidence for the other species right what we can say is that naletti is different from Australopithecus we have some really impressively complete hands for Australopithecus sediba um a lot of hand bones for Africanus and a good number of hand bones for offerensis and in the components of the wrist the length of the thumb and the fingertips they look pretty different from nobody ladies like us Melodies like neanderthals as well right it's like us and Neanderthals in those details it's different from us in some really interesting ways also it's its finger bones are quite curved we think that this is probably to do with climbing but we're not positive about that this is something that actually the expert in the world is sitting here because nobody else has thought about it as much as you have at this stage if if life goes well with Sarah her dissertation work is going to be on these kinds of topics so so that's that's what we're investigating yeah um one more question over there and if you can well I walk over there for you to answer this um previously you talked about how important you thought 3D printers would be in sharing these incredibly valuable fossils yep if I can use the right word can you tell us more what's happened in the last four five six years since last you were here and you talked about how that was changing the field absolutely um we have a little Factory going in the social sciences building now with 3D printers and we're actually able to print not only the niletti fossils and the Australopithecus sediba fossils that our team is working on but we print fossils from all over the world and they're here in our classroom we've been able to augment our teaching here at the University with these 3D printed materials and we're able to visualize things that don't exist in reality we're able to take for instance the insides of skulls and make them into virtual endocasts that that we can handle we're able to take teeth and high resolution scans of teeth and print them out into large sizes that that we can compare and allow students to interact with we could do experiments on if we chose to so there's sort of amazing things that we we're actually also visual realizing the cave system in three dimensions and we can print the cave virtually and sections of the cave walls so there's there's quite a lot we do with that the availability of the data from this that is now online a site called morphosource.org anyone can sign up and download fossil materials from this site and our fossils are all there and a growing number of fossils from other hominin sites in addition African fossils.org has made available fossils from the Kenya National museums collection that that Richard and me vliki have been especially associated with so that you can actually print and interact with many of these these are now part of high school curricula there are high school help groups that help people get started with printing or distribute prints to high schools that can't get prints of them there are curricula written now for AP biology for high schools to be able to use those in classrooms and we're getting them out into classrooms worldwide including in South Africa which is our commitment to to be able to outreach to the public in South Africa the country where we're working and where our team is based so so it's made a tremendous difference we're now working in undergraduate classes with 3D data from fossils and from human skeletal remains and doing original work and that's something that wasn't possible five years ago it is changing the way that we educate it's changing the way that we encounter evidence and people are printing them and put on their bookshelf too there's nothing wrong with that yep okay the question I have is concerning external of the cave have have you done any archaeological work external of it uh either planned or chlorine samples to find a range of Ring of the people that were there yeah we do have archaeological survey from the immediate property and from The Wider cradle area the Cradle of humankind is a world heritage site I call it that because it's the name of the heritage site and it covers an area of about I would say about the size of the city of Madison maybe a little bit bigger even than yeah actually yes a bit bigger than the city of Madison is part of the world heritage site that area is protected in you know in UNESCO terms uh it has caves in it those caves many of them have Heritage from different eras some of them go back two and a half to three million years some of them have Heritage from Iron Age peoples who lived there 500 years ago so there's a lot of of Heritage in the area on the rising star property we don't have any contextualized archaeological sites on the surface we have done survey of the surface there is late Stone Age archeology that's present across the landscape you know scatters of tools and refuse from Tool making there is Iron Age archeology in the immediate nearby area so so we know that peoples have been busy on this landscape in the last 20 thousand years before that we have Middle Stone Age sites that including swartcrons which is a cave site where Professor Travis Pickering on our fat on our faculty is the primary investigator there he works there every year and it's about 800 meters away from the rising star Cave System it has abundant evidence of humans or some other kind of hominin being there making artifacts in the range from 80 000 years to a little earlier than that and then in addition to that older phases it's a complex landscape we're still finding times that are underrepresented and as in the rising star case sometimes there's something there we didn't expect and that's that's the situation for us what we try to do after that is to say do we know of anything else that is the same time period that might be connected to this it might be in a different cave it might be in a different part of South Africa it is difficult for us to associate things in that way but we are working in in several cave systems on that problem Gladys fail cave for instance is a site where caneloy molapiane Works where we have evidence of hyena activity and and remains that are associated with the hyenas including hair casts within hyena copper lights from some kind of human relative that are in the range of about 250 000 years old as we continue to investigate that site we may find that hey these are naletti hairs and that's the kind of thing that we will be able to do but it takes a lot of time and a lot of work to try to correlate across sites in that way two last questions uh one is what was the name of your colleague who might want to give a Wednesday night the lab there Mike oh Travis Travis Pickering Professor Travis Pickering yeah great thank you and the last one was online um I think the person was asking have you uh compared or done the ratio of brain size to body size ah yes um naletti is interesting because they're somewhat larger in body size than most of the earlier hominins like Australopithecus who had similar size brains and so in their brain body relationship they actually score as more different from us than something like Lucy um that's purely a function of them having gotten bigger in bodies and not bigger as much in brains what the importance of that is is not clear when we plot body size versus brain size and hominins there's a pretty good relationship and we know that getting bigger Bodied has the consequence of getting bigger Brains it's also the case that if you were selecting for bigger brains it would have a side effect of making you bigger and evolution works that way if you select on one correlated character the other ones come along with it and we don't know what direction selection might have been or whether there was selection whether some of the brain size changes might have been genetic drift

Channel: Wednesday Nite @ The Lab

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Length: 107min 7sec (6427 seconds)

Published: Thu Feb 09 2023