this ucsd-tv program is presented by university of california television like what you learn visit our website or follow us on Facebook and Twitter to keep up with the latest programs you the topic of my my talk I'd like to add a subtitle to it with which R is respect to the the fact that Carta seeks to engage the various factors that are part of an evolutionary explanation of human existence on on earth and the ways in which human beings and climate are wrapped up with one another I think is a is a very interesting and important thing to think about because environment and the environmental conditions of human evolution set the the context for natural selection for population separation and speciation and also for extinction which of course is part of the whole matter of why Homo sapiens is the last biped standing the traditional idea that has been a focus of the environmental history or of our environmental context of human evolution that has lasted for many many decades is what we may call the savanna hypothesis of human evolution that protohumans six million years ago or more were set out on to a savanna grassland and in this context in this very basic setting of the stage of human evolution environmentally came a cascade of all things human ranging from fundamental traits about how human beings get their food how we gather the energy to support our hungry brains and how we evolved the capacity for culture that is very much oriented toward human transactions with our surroundings today this is an idea where the environment doesn't really play a major role because there's just basically a setting of the stage and what you get this cascade from is one adaptation setting the stage for the emergence of another but we have learned a lot in the environmental sciences over the past decades this is an iconic slide or a iconic dataset with regard to the last 10 million years with 10 million years over here present over on the left side and this is a based on study of of oxygen isotopes two forms of oxygen oxygen 16 and 18 in microorganisms foraminifera that live on the bottom of the ocean floor and collected in deep-sea cores and what you can see from this is the that there has been an overall trend toward a cooling planet but a lot of research recently is focused on the the nature of the variability before six million years ago and this can be traced back to 70 million years ago these kind of data you have relatively low lying variability and after six million years ago you have a ramping up of the amplitude of a fluctuation since three million years ago there has been an intensification of glacial fluctuations and the genus Homo evolved during the strongest fluctuations with the species Homo sapiens associated with even the most strongest in this timeline of ocean temperature and an glacial ice on on land at the same time we have learned a great deal more in the last decade about african about tropical African climate this is one of my favorite records which is thus a propel record whereby the the dark and light bands the dark bands are organic-rich extrusions from the Nile catchment into the Mediterranean Sea and the light bands are relatively dry periods and one can see this back-and-forth of tropical climate variability not between glacial ice not between warm and cold so much but between wet and and dry and one can see then that these these dark and light bands are bundled in two periods of stability and an instability over time and of course the SAP rappel record related to the Nile catchment basically captures as a record of climate that records from the northeast quadrant of the African continent and therefore is particularly relevant to things going on in eastern Africa and this dark dark light banding can be captured in spectral reflectance of the darkened light bands with the light being strong aridity and the dark higher moisture and this is a record from the last three million years ago and it shows the nature of this variability but the fact also that it's patterned into these high and low climate variability intervals and I've just outlined two of those examples from this particular data set this particular SAP rappel record from the eastern Mediterranean now we've learned a lot also about the causes of this the tempo of dry wet seasonality and dry wet expression of climate over many many years is the result of what's called orbital precession the related to the wobble of the Earth's axis of rotation and that is modulated it's affected by eccentricity by the the path the shape of the the Earth's orbit around the Sun from more circular to more elliptical or oval-shaped and during times of high eccentricity there is a raising of the amplitude of wet-dry variability and it's been pointed out by quite a number of researchers over the years that the interaction between the two timescales of orbital precession and the two periods of eccentricity results in a predicted sequence of high and low climate variability and you can see that represented through time from about this in this case plotted from about 1.8 million years ago to the present and you can see the time period of greatest interest to to us in this particular symposium involved a quite a prolonged time period of high climate variability it also through mathematical modeling we can establish the boundaries between predictive framework and the boundaries between high and low climate variability and so for the for the first time let me show you then for the time period related to this symposium the the alternation of high and low climate variability with the high defined by periods of high eccentricity this is the low boundary the difference between low and high is that amount of eccentricity which is one standard deviation below the average eccentricity for the last five million years these are the intervals of times and thousands of years ago so 38 to 48 thousand years ago is what I've taken this up to and I've given a slightly broader context back to 638 640 thousand years ago for looking at this particular series of dates for predicted high and low and we see that these are the durations of these particular time periods of fluctuation of of change from relatively stable climate to in stable climate with high degree of fluctuation between wet and dry for eastern Africa and this is I put this bar here related to the last four hundred thousand years ago and one of the things that really pops out is this very prolonged period three hundred and six thousand years in duration predicted for high climate variability starting about three hundred and fifty six thousand years ago and ending about fifty thousand years ago and this encompasses the entire time nearly the entire time period of what we're talking about here in this symposium and certainly the entire time period of the development of human innovation as expressed through the middle Stone Age which you'll hear about later the origin of our species the beginning of this dispersal of Homo sapiens out of Africa now there are relatively few good empirical records other than SAP rappels in the dust record and blown out into the the deep sea that really tells us about what's going on in Africa during this time period the best one that's continuous drawn from a core from lake lake malawi and what has been published so far is a hundred and fifty thousand year record dry/wet fluctuation based on a variety of lines of evidence and this has been called evidence for mega droughts time which is maybe a little hard to see over here it goes from about 150 thousand years ago to the present and what I've done here is outline the time periods of what the authors have called the mega drought periods it's a bit of a misnomer in that what it tides is the fact that this time period actually involves a tremendous amount of fluctuation in Lake Malawi level Lake Malawi today has a depth of water depth of about seven hundred and six meters below the surface and there are times in the past during these mega droughts when it went to about 125 meters depth but even within these mega drought periods such as this prolonged one here there's considerable fluctuation in moisture and drought another excellent synthesis that exists so far for the last 150 thousand years ago comes from an article in journal of human evolution by blow meant at all and it synthesizes data from around the African continent relatively little from eastern Africa Eastern Africa but nonetheless on the basis of this shows a variety of back and forth between wet and dry from a hundred and fifty thousand years ago to about thirty thousand years ago and two important points here that are in line with this predictive framework of high and low climate variability is that there is stronger variability prior to 50,000 years ago then there is afterwards some of these places also have different histories of climate variability notice the differences between for example South Africa and and North Africa and so what I've done here is to indicate for the last five million years based on this predictive framework the eight longest intervals of predicted high climate variability here's the one that I just introduced the one between fifty and three hundred and fifty six thousand years ago with the duration of three hundred and six thousand years what occurs is that the entire Middle Stone Age unfolds at least in in Africa during that time period Homo sapiens evolves and the global dispersal begins but I wondered in these other prolonged high climate variability intervals what else happens in human evolutionary history this is what we see in terms of some of the major first and last appearance is based on the fossil record right now so this is likely to change in a number of years as new fossils and archaeological remains are found but what we have at this stage is that the origin of every major genus in our evolutionary tree Australopithecus homo and paranthesis happened to at this point fall in a prolonged high climate variability interval and that the origin of every single major technological suite of behaviors the old one Julian end the middle Stone Age also occur in these time periods of high climate variability this suggests that one of the hallmark features of our evolutionary history including the emergence of Homo sapiens and probably related to the extinction of other forms is this matter of adaptability and the big question in front of us then is how does adaptability evolve and emerge over time by adaptability I mean this and this is not just in relation to humans but any organism the ability of an organism do endure change in its in its habitat where it happens to live at any given point over time and space to be able to thrive in new places and novel environments to spread to new habitats and to respond in new ways to the surroundings and of course these are characteristics which some people would say that Homo sapiens that's really the hallmark of our species in terms of our environmental interactions well where we have been investigating this kind of matter of adaptability and evolutionary change for the most / long time in my career the last 28 years is in the sight the basin of Ellora gastly it's in the South rift of Kenya you can see this beautiful layering of layers and environmental change over the last 1.2 million years the most precisely dated sequence of archaeological and false fauna and environmental change over the last 1.2 million years and what we see in very summary form is that between 1.2 and 500,000 years ago we have a surely in hand axises suite of behaviors that resulted in the repetitive production over such a prolonged period of time of hand-axe technology these large cutting tools these scales here are centimeter scales and by this time period and we're investigating this right now and beginning to write articles on this work with the my colleague Allison Brooks our colleagues K Burns Meyer Alan Day know are beginning to put together papers on this but by this time period we seem we have middle Stone Age innovations the eschew lien is no longer around and you have the beginning of human innovation back this far in time and that includes smaller more mobile technologies and the ability to make tools through preparation of the core and new techniques the ability to repetitively produce these small triangular-shaped things which may be projectile points and the even the accumulation on certain sites of coloring material black and red coloring material we also see during this time period the total turnover in the fauna of the southern Kenya rift where the large body grazing animals the animals of the Savannah become extinct and they replaced by their modern Representatives of hippos and elephants and zebras and baboons and pigs that are far more flexible and adaptable in their ability to change diet change demographically in their group size and so on and so this can be added then our work in the southern Kenya rift to this iconic diagram that was first produced and has been reproduced by many times but drawing on the work of Sally mcbrady and Allison Brooks in a very important paper from the year 2000 I've added a few things here as well and what's interesting in this time period from 2.2 hundred and eighty thousand years ago to twenty thousand years ago you see these innovations in the middle Stone Age so different from what was occurring in the Eshoo lien and the repetitive behaviors we're occurring and what's exciting about our work in the South rift is the possibility of extent extending some of these things back before three hundred three hundred and ten thousand years ago what these represent then is the emergence of smaller more mobile technology increasing innovation wider social networks possibly including exchange for the first time with with distant groups and complex the development of complex symbolic activity these represent ways of cognitively socially and technologically buffering the vicissitudes of the surroundings including the social surroundings and I think that the context of high climate variability after periods of low climate variability make sense of this emergence of the ability to to buffer behaviorally and culturally what's going on and what's the future of this just to conclude we obtained for the first time from any early human site in Africa a long drill core from from a legacy Lee this was quite an undertaking but here's the drilling project and ending just last week last Friday was our sampling a core sampling party where we got a chance to split the core an international group of scientists 22 scientists came to study begin study of the core and this is the first public showing of what that core looks like one small bit of it split this is quite representative these are there are 68 tephra layers of volcanic layers that are amenable to dating through this time period we think that 206 millimetres of sediment 216 meters of sediment represents the past 500,000 years in utter detail including these varville like deposits which we think represent seasonal variation in rainfall and how then we will be able to test how those seasonality changes in seasonality are grouped into longer periods of higher and lower climate variability and so we think that this is the the future work that will make this whole project of the climate conditions of the emergence of Homo sapiens and ongoing an important area study thanks very much I'm presenting apologies for Sally who had something come up rather recently and could not be here but she is represented in in the slides so I'm talking about East Africa and we deliberately put East Africa in front of South Africa because a lot of the though we're now beginning to find out about the longer record of South Africa it has been a much shorter record in terms of the time span than what we've had in the East for a while but the question then arises where exactly is East Africa if you look at a fighter geographical region map like this one that's recently been published by the American Association of geographers you see that actually there is an elevated area of woodlands and savannas with a lot of altitude '''l diversity that surrounds and is in the East African Rift zone that actually has a great deal of similarity in not that it doesn't have a great many different terrestrial ecosystems within it but it actually comprises a geographical zone this this olive green area this is an area that about half of it experiences too many seasons a year which makes it a much richer place and it's also an area where the the rainfall zone is wider north to south because of the influence in part of the Indian Ocean monsoon this area has and has had for some time the world's largest terrestrial mammal biomass per hectare or whatever and theoretically then it can support the largest population of predators among which we have to include the humans for the last couple of million years anyway okay and then the question is what is the middle Stone Age which is the second part of what I'm going talk about and we could define this as a complex of stone tool industries which spend the transition from archaic humans to us but that doesn't tell us much about how you recognize it if you're out walking around and it's distinctive in its emphasis on hafted points and other tools that are shaped by retouch or pre-shaped on special course this goes along with greater hunting competency so we also see in the middle Stone Age not necessarily from the very beginning but certainly as it continues the first signs of symbolic behavior including personal ornaments and grabbed and painted objects and rituals first signs of regular long-distance exchange and we also infer a dramatic increase in the complexity of human cognition from the technological and economic strategies that we see within developing within the Middle Stone Age the fishing the trapping small animals the making of composite multi element tools and the expanded social networks among other things ok this is a different paper from Blom it all which I have to confess to being one of the co-authors Oh which is why it's so enough so much this is rather than showing the places from which we have environmental information this shows us the archaeological sites in the last of middle Stone Age affinity in the last 150 thousand years and you can see that if we had drawn if we had drawn this map 20 years ago there would have been almost nothing that was dated in Eastern Africa but there would have been some sites in North Africa and a concentration of sites in South Africa and while it's still dominated by South Africa the other areas are filling in when you realize though that Africa is more than three times the size of the United States you realize that the middle of it is extremely under studied but nevertheless we can begin to say something so what I want to do is very quickly go over the late Middle Stone Age since the first modern human fossils attributed to Homo sapiens at about 200 thousand years ago and how it relates to what we'll hear about perhaps from the South African record but some traits that I don't think show up in the South African record we do have beads occasionally from East Africa we have fishing from East Africa also represented now in South African record we have barbed bone points however used for fishing in the eastern zone one of the unusual things about this record which may not be unusual when they start looking at it more in South Africa but we do have from very early on it on we have long-distance trade and transport of obsidian in this late time period we'll be looking at how far back it goes we also have possible burial rituals at hairtail 160 we have complex projectile weapons at multiple sites including geometric shapes what's distinctive about the East African ones is the very widespread and persistent existence of very small by facial foliage which are little leaf shaped points that resemble North American arrowheads and we think they actually were in all likelihood arrowheads and this is an example from a Duma in ithi in Northeast Ethiopia where I worked in the 1990s and here we have a progression from the points the big points that are more than a hundred thousand years old to much smaller ones that are perhaps ninety to 80 thousand years old above and all of these points of the tree are trimmed at the base for hafting almost all of them are are obsidian or chert from four to eight different sources and there are no local sources so again we're looking at long-distance movement of this material the small points we've we've now agreed among the people who study these things that the small ones are in fact elements of a complex projectile weapon system which if you think about it if you're going to invent something like a bow and arrow we have to accept that you're a modern human these are some other kinds of points from Moomba in Tanzania where the Middle Stone Age goes from the bottom of the site to here and the bottom is about a hundred one hundred and twenty thousand and this is about forty thousand right here and these are in this upper area at perhaps fifty thousand these geometric shapes and right the way through the sequence but especially in this upper part the this is in northern Tanzania but the obsidian is coming from Kenya about two hundred and thirty kilometers away and in addition to stone points we also have bone points these are from coton de in the on the western edge of this Eastern zone in the on the edge of DR Congo at dated to about sixty to eighty thousand years ago and associated with the bones of very gigantic fish that's actually bigger than this one that we were catching and there's a whole suite of these there are three different sites that we found them at in association with middle Stone Age artifacts um there's also a possible of the possibility that we're looking at mortuary practices in this time range Tim white has argued that the polish on this child skull from here toe in Northeast Ethiopia dated to about a hundred and sixty thousand years ago is polished you can see these areas of polish on the back of the skull here and it's polished from somebody holding onto it and rubbing it when it was already a skull and then he argued that this could be part of of a kind of mortuary ritual we also have we very rarely have personal ornaments in East Africa because most of the sites are in open-air locations where the organic preservation is very bad so if they're not making beads out of stone which we don't think anybody in Africa seems to have done then we're not going to recover the beads but where we do have caves it's interesting that in three of the very small number of caves that we have in Africa we have probable evidence of beads so this is an company yaa Muto in Highland Kenya about 50,000 years ago and we have not only ostrich egg shell beads but the manufacturer of ostrich egg shell beads along with these very large geometric forms and also once these geometric forms come in they stay that keeps developing in that direction into the lehder doughnut we don't see a disappearance of these geometric forms and then their reappearance later okay these are ostrich egg shell beads from Mamba again towards the top of the sequence but I was able to date one of these by amino acid racemization 250 2000 years ago and there's recently been a similar day in the very early 40 thousands for such a bead and then these are from poor Quebec Cove in Ethiopia dated 233 to 60 the argument here is not necessarily that these are man-made or anthropology anthropogenic perforations but that the distribution of these a perc EULA in the complete absence of a of the rest of the shell suggests human agency in some way these are were collected were collected and described by Salalah merciful and colleagues so what about before Homo sapiens in the early Middle Stone Age what if we go back if all of this is characteristic over the last two hundred thousand years ago what do we know about the development of this and what happened before this so before this what we have evidence from and I've put in red what we have in in Africa that is not I think shared with Neanderthals because when we go back if we're going back into the past we're going back to the last common ancestor period that Chris just put up into the divergence time he just put up so we have to think well if the Middle Stone Age turns out to begin four hundred thousand years ago did the Neanderthals leave Africa with the middle Stone Age so it turns out that Neanderthals share some of these features although the interesting thing is they share them quite a lot later so we have to wonder if there was a another out of Africa's if there was a exodus of Homo heidelbergensis out of Africa and then another exodus with some of these cultural features that we're not catching in the fossils so what we have are these these very sophisticated technologies for making shapes on the core for taking a core shaping that core into a particular way which is very complex and has to and has to be learned and it does imply sophisticated sequential action and conceptualization there are a lot of stages in making this that don't seem to be leading towards the final product unless you can really carefully imitate somebody teaching it to you and we see these by 500,000 years ago so that's really the beginning and it may begin before that in the context of the final Julian then we see these long-distance procurement networks I've also already mentioned and they're procuring the raw material not just the finished pieces which is another difference we also see these hefted weapons very early on we also see large quantities of ochre kilograms of ochre Insights processed into powder but what we don't see our ornaments engravings or burials with grave Goods so there are some differences with the later period this is the the again this graph that we published in 2000 and just to put some of this other here are the the fossils we had an end date of 280 thousand years ago because we thought at the time that was the beginning of the Middle Stone Age but since then we ourselves have proved that this was incorrect we do have these things appearing and disappearing but what the red line show is how far back these things now extend to considerably before 280 thousand years ago in many cases so what we just a picture of what these prepared cores involve that this allows that these allow the production of very thin flakes and points which are shaped on the core and these this technology appears in Africa just before or at the same time as the first specimens of Homo heidelbergensis about 650,000 years ago it's a very abstract idea to go from a lump of stone not to the finished piece but to the core that is then pre-designed to knock off one of these special flicks this is a pre shaped Lavelle wa point from alors ghazali just to show you a real one okay I'm going to also talk about Sally's material she has sent some slides and texts to go with it this is her work in the northern Kenya in the captor in formation where a lot of the material was under a tough dated to two hundred eighty-five thousand years ago this is one of our advantages in East Africa that we do have a lot of volcanic switch can be dated by argon argon to very precise degree and here she has a series of blades which had been published on which are older than 285 and again this is something that Neanderthals eventually did but she also has even older blades and cores designed to produce blades from before 500,000 years ago so the idea of producing these very standardized products on a single core again is something very complicated that we don't see earlier the transition from the Australian to the Middle Stone Age involves significant changes in stone tool kits eventually they give up the hand axes and they start producing points these are parts of composite tools you need to make a hafting material and system which could involve binding could involve glue you it takes a long time to make a half that you you tie them to you can't just take any old stick or it's not going to fly straight Spears and then when you break it you need to work a figure out some way to fix it to repair it Spears are lighter and more portable than hand axes and ethnographic analogy suggests that stone tipped weapons are particularly effective for large mammals so where do we have some of these points this is a very early sequence from guru mata and ethiopia where we have some very small points like this one or this one that are trimmed at the base for hafting here's another one trimmed all the way around is very flat invasive working into a perfect symmetrical shape its characteristic of the East African material we also have these blade like forms but very small with retouch basis as well we don't quite understand what those are for and all this is at most of this is at least two hundred and eighty-five thousand years ago this is sally's material from the captor in and this is under a tough dated to 230 series of tufts to 35 to 284 with more than 2,000 artifacts in situ under this tough some of the artifacts are points like this and they're made of obsidian and the obsidian they're also labelled Wow points which are shaped on the core which are very thin and symmetrical and straight and the thing about the obsidian is you can trace where it comes from and Stanley Ambrose has been involved in a lot of the tracing for both Sally's work and our work at allure ghazali and the there were little chips that fit back onto these points and he was able to take the little tips and figure out where the source was so that and in this case the points the basic point may have been shaped elsewhere and then refined or finished at the site where did where is the elsewhere at least a couple of sources one of which is a hundred and thirty kilometers away so again very long distances that this material is traveling okay at a Vargas oily and you've heard something about this this is sites in an in a locality that we just call B with a tough running through it that is stated variously to 305 to 312 and underneath is tough we have Laval flakes we have coloring material we have disk various kinds of cores and at this site be okay - which is under as you see it's under the to toughs 305 and 313 here in the wall all of these little black spots there are multiple occupations here and all these little black spots are obsidian in fact 55% of the plotted artifacts are obsidian here here they are and the lithics include shaped points Laval points a whole series of small scrapers we also have blade 'lets and bi-conical blade lead cores although these are not the blades we have in the late Stone Age it's nonetheless an emphasis on a very small tool type and we also have the course we have Laval what cores we have that point that Rick showed you and then I'm showing you actually fits back onto a Laval core so it isn't just the finished artifacts it's the whole turbine so where is it coming from we have here's a log a salary a scale of 120 kilometers we have multiple sources again and some of them are 40 kilometers some of them are 60 and there's coming from at least four different directions and that's we still have 40% of the samples we've looked at that we don't know where the source is so there's a great diversity in where the material is coming from and a great deal of the material at the site so the local raw materials are mostly quartzite sand courts in many of these DC African sites including a Duma including lor Ghazali including the copter in but the points are preferentially made on very fine-grained materials which have to be brought from far away so what's the implication of this far away transported material if it's a large home range you have to know a lot about the environment and you're going to meet a lot of individuals you're going to meet people from different groups going to these sources and you need some way to identify yourself as a friend so it's not surprising that pigment goes along with it and it may be that they're trading with these other groups and that this wide network of early a ship's provides a way to deal with climate variability to buffer you against environmental risks okay pigment this is the last topic this is from the captor in a grindstone with ground fragments of ochre this is from allure ghazali with a lump of what we now think is an iron rich mineral which has been ground on one side to release a powder and this is a close-up seeing the grinding striations here from it and this is from Twin River Zambia just so that we get central this the southern part of this area in here and here there are many kilos of ochre more than six kilos in these little pieces that are many of which have been ground so in conclusion the the sort of take-home message is that there is a gradual transition to us that begins at least 500,000 years ago and by the time we get to 200,000 160,000 years ago and people are beginning particularly let's say by a hundred thousand years ago to make complex projectile weapon systems were probably and to conduct mortuary rituals we probably are very much dealing with us so thank you good afternoon I'm going to be talking about the archaeological evidence for complex cognition in the Middle Stone Age of South Africa what do I mean by a complex cognition in the simplest terms complex cognition implies the ability to think in the way that we do today and in defining the Middle Stone Age in the South African context I talked about industries that appear with the earliest anatomically modern humans about 300,000 years ago but as we heard from Ellison a little earlier the Middle Stone Age technology may go back as far as 500,000 years ago I'm choosing some attributes of complex cognition to talk about today the use of symbols planning for remote action that is when the human actor is some distance from what is going to take place thirdly the practice of delayed gratification which we can also call response inhibition and an example of that is when people collect ostrich eggs from a cache and leave some of them behind for the ostrich to headshot the ability to multitask the ability to be flexible in problem-solving understanding transformation and by that I mean technological trance transformation transformation being that the change for example in in artifacts that are irreversibly changed so a number of ingredients irreversibly changed and finally the use of analogical reasoning these attributes are likely to have been incremental they would not have arrived as a package I've chosen for South African sites to give the examples from three of them are in the Cape deplore pinnacle point and Blum boss and the fourth one is in Qualis kwazulu-natal at the beauty blonde boss is a tiny cave site it's a coastal site and it's yielded a number of amazing artifacts that I'll be showing you in a moment the site was excavated and is being excavated by credential wood the ages here go back to about a hundred thousand years ago Pinnacle Point excavated by Curtis Marion also a series of coastal sites on a cliff and the ages here go back to about a hundred and sixty thousand years ago deep curved inland this is a rock shelter that was excavated by French team directed by Tixier and Perez and in collaboration with a South African team directed by John Parkington and Cedric Popkin pool and Sebu D which I have excavated up until 2011 it's now being excavated by Nicolas canard the site is perched on a cliff in an evergreen forest about 15 kilometres inland from the sea and it's ageless go back to about 77 thousand years ago so the first attribute the introduction of symbolic thought one of the things that to note this is the the introduction of perforated shells at Blum Bosque the age there is about seventy one thousand years ago and these Arles aureus shells many of them at Cebu do it's a different species F roulette arena and well shows but the age is also seventy one thousand years ago the importance of having these perforated shows is that these ornaments because we believe there are elements are markers of self or group identity which in turn is an indicator of symbolist then both Blum bus and Cebu do feature here again with the presence of engraved oka the Blum bus ones are really famous they go back about a hundred thousand years ago and the best known of these is on the left hand side the one with the cross-hatching at Cebu do we don't tend to get cross-hatching designs there the designs are more fan-like as you see at the bottom and the edge for the Cebu D ones like that is seventy seven thousand years ago deep claw of rock shelter is well known for its engraved ostrich egg shell these come from perforated water bottles on the top right are the perforations that you can see on these pieces of water bottle and the decorations the engravings over on the left here what is most noticeable about the the deep cliff engravings is that the patterns tend to be these leather light designs and these are repeated on hundreds of pieces of the eggshell suggesting that we're dealing here with a cultural tradition not something and that was uncommon at all in the Kalahari today such ostrich egg shells are used as water bottles only a few of them are decorated and you can see one example there on the right but the most compelling evidence for complex cognition I believe comes from everyday tasks and so I'm going to be talking mostly about those the introduction of snaring implies planning for remote action and response inhibition so the setting of a trap implies that the hunter is going to gain meat without actually seeing the prey that comes to the snare or the trap and at Cebu do there is evidence for this circumstantial evidence about 71 thousand years ago the fauna there is dominated by blue day care a very tiny animal that lives in the forest and would certainly not be sensibly caught either with arrow or with spear then the bush peck which is not ternal extremely dangerous to hunt and so far more likely to have been caught in a pit trap and then the tiny carnivores things like mongooses these are not susceptible to being caught in in Nets so we can probably eliminate the possibility of nets but they are susceptible to be in court in snares I think one of the most convincing butts of evidence for advanced planning and multitasking comes through the introduction in the middle Stone Age of compound adhesives I have to tell you the difference between a compound adhesive and a glue a glue is a simple product like a plant gum whereas a compound adhesive is a combination of ingredients and the combination of ingredients that I'm talking about here is plant gum like acacia together with ochre powder with Sunstone artifacts both agarose cottage and sebou tea that have these compounds adhesives on them and so in order to try and understand how they were made I did some experiments to transform a combination of powdered ochre and acacia gum into a compound adhesive the advanced planning comes with collecting the materials the acacia gum has to be connected the the ochre powder needs to be ground from pieces that can often need to be collected from great distances then the important thing about this is that these natural ingredients defer quite considerably depending on season and where they are collected and the end result of that is that there is no set recipe like a cake recipe that can be used for making these compound adhesives sometimes the acacia gum or the other plant gum is runny and more ochre powder needs to be added on other occasions the gum is stuff and so less okada needs to be added and so this is all about thinking on your feet while you're making these things switching a tension changing plan and indeed multitasking but the really compelling evidence here for multitasking is once the person has mounted the adhesive onto the shaft and attached the stone tool and then needs to heat this to dehydrate the the adhesive on the tools and so it's the control of the fire that is ultimately so important if the fire is too hot the adhesives were will boil and bubble and get air bubbles and be useless or they may burn if they too close to the fire and so without temperature mechanisms people in the Middle Stone Age would have had to gauge how warm the fire was and how suitable it was for dehydrating without spoiling these tools so a good example in short of multitasking here are compounded his adhesives at Cebu do by seventy one thousand years ago they're the examples pictured here are in fact sixty five thousand years ago over on the left is a segment and I think that you can see there is Oka adhesive attached there where is the tool on the right has a different recipe and that recipe has no ochre in it that it has black fat and in the center you can see the microscopic images that go along with each of these tools the tool on the left has indeed ochre on it under the microscope and plant gum up at the top whereas the the tool on the right has fat on the top image and a series of black fat and white fat if you look carefully at it the importance of these different recipes for compound adhesive is that the okra was not necessarily used symbolically when the adhesive was made if it was used symbolically only within these recipes we would expect that all the adhesives used at the site would have had ochre and in them so that the hunt was always successful and that was not the case they were different recipes the introduction of compound paint which we see at Blum boss at about a hundred thousand years ago follows exactly the same principle although it's not compound adhesive it's a compound paint made of ochre charcoal crushed fatty burn quartz grains and an unknown liquid my latest work has involved heat treating of rocks and the heat treating of rocks in the past I believe believe indicates analogical reasoning let's have a look at why that would be the case some researchers using electrical furnaces have suggested that it's not necessary to bury silesius rocks underground in order to heat them successfully however my experiments with fires which behave a little bit differently from electrical furnaces suggest that that's not true at the top left are buried silk wheat slabs which I cut into two different sizes to imitate the preforms that might have been used for the manufacture of stone tools once I'd buried those I've put similar blocks of silk wheat on top of the ground laid the fire on top of that littered and subsequently scraped off a coal bed on which a third set of soaked wheat blocks were cut in short the Salt Creek blocks that were buried underground preserved perfectly whereas both the ones in the fire and on the coal bed fractured as you see in the bottom left picture one of the experimental fire temperatures is shown on the right the upper graph shows the temperatures in centigrade of the fire itself I want you to notice hardly the temperature ramps up very quickly within the first five minutes is a little bit uneven and then drops extremely quickly where is the underground temperatures depicted here rise slowly fall slowly and maintain a very nice curve in the middle the temperatures here are between 300 and 400 degrees exactly the temperature that is needed to transform so Crete let me explain why this should happen when cell Crete is heated it changes its structure it becomes more fine-grained and the poor waters in the center evaporate art if this all happens too quickly then the soar Creek fractures and that's why the underground temperatures are ideal for making this transformation and why is it an illogical reasoning simply because in order to get the underground temperatures that are required the above-ground temperatures need to be controlled very carefully here are the archeological examples that suggest that heat treatment did take place in the Middle Stone Age at Blum boss at 71 thousand years ago there are some points a and B that demonstrate heat treatment the way that heat treatment can be seen in these artifacts is that when a piece of rock is heated underground or heated at all and then struck the the flags that have been removed show a gloss a luster whereas the exterior of the rock that has not been struck does not show that lustre so both experimentally and archaeologically we can see that there were preforms pre shapes layered on and to be heated and that they were subsequently flat and Carl brown has done experiments with pinnacle point rock and has looked at some of the the tools from the site to demonstrate that those have been heat treated in summary let's have a look at the the selected evidence that I've given you for the attributes of complex cognition in the middle Stone Edge first symbolism expressed through group or individual identity then the long-term planning for remote action and response inhibition through the circumstantial evidence for snaring multitasking through the the manufacture of compound adhesives and compound paint this also shows the ability to be flexible in problem-solving then the concept of transformation is also present in these company compound adhesives and paints but also in the heating of silesius rocks in which I also suggest that analogical reasoning which may be one of the cause of our modern thinking it's also visible thank you
One of the enduring questions of human origins is when, where and how we "Behaviorally Modern Humans" emerged and why and how we eventually replaced all the other human-like species. This series takes a fresh look at the situation today with a critical examination of the available evidence from multiple sources. Rick Potts (Smithsonian Institution) leads off with a talk about African Climate of the Last 400,000 Years, followed by Alison S. Brooks (George Washington Univ/Smithsonian Institution) on East African Archaeological Evidence, and Lyn Wadley (Univ of Witwatersrand, Johannesburg) on South African Archaeological Evidence. Series: "CARTA - Center for Academic Research and Training in Anthropogeny"
Why was UC forced to take stuff down?