Evolution of the Human Brain

well good afternoon ladies and gentlemen it’s with great pleasure that I was invited to introduce this afternoon’s lecture i’m professor richard Evershed from the university of bristol I’m a biochemist whose interest overlap somewhat peripherally with with professor mark mallet Maslin who’s going to be talking to you I just have to mention a few formalities could you all make sure your mobile phones are switched off thank you very much the lecture will be about 40 minutes there’ll be time for some questions at the end and I thought I’d start by just saying a few words about the Royal Society who are organizers of this particular lecture and one or two other lectures in the in this in this festival and I I thought I’d just say a few words because sometimes I think people don’t quite appreciate the significance of the Royal Society as an organization it is the most prominent scientific society of the British Isles and it’s an organisation that is a self-governing fellowship of some of the most distinguished scientists English scientists in the British Isles and we also have very distinguished foreign members as well and the fundamental purpose of the Society is truly promoting excellence in in science and it serves the Society of performs a number of functions as well as being a scholarly society which which which actually funds science fundamental science it also supports a larger number of lectures and other events such as this and it also performs an extremely important function in providing what I would describe as a sort of rational advice to government on some of the most critical scientific matters of a day so it’s a very important important important organization but the purpose of this event is one very much the one which is right at the heart of the Royal Society as well and that is to is to is to promote the wider interest inside public interest in science and I would strongly recommend for those of you that haven’t done so that you go to the Royal Society website and look at all the events that the Royal Society takes part in and you can think you can even view some of the past lectures on Royal Society TV so I draw me recommend you do that anyway that’s enough about the Royal Society now let me say a few words about our speaker professor mark Madeleine I’ve known mark for quite a few years he’s professor of paleo climate ology and he’s from the University from University College London I I know mark from his from his from his scholarly activities but I didn’t realize quite what an entrepreneur II was when I started to read a little bit more about him he’s his co-founder and director of carbon associates limited his science advisor to the global coal foundation global precious commodities PLC and carbon sense limited but actually most importantly mark is a member of the Cheltenham Science Festival advisory committee which is by far his office his most important role his areas of scientific expertise include the causes of past and future global climate change and he has a particular interest which we’re going to hear a lot more about in the early human evolution he’s published or more than hundred papers he’s written seven popular books and he is a Royal Society Wolfson Research Merit Scholar for his work on early human evolution and he’s just been awarded a four year Royal Society industrial fellowship he’s just returned from a workshop on theories of human evolution held at the Turkana basin Institute in northern Kenya which is hosted by the very famous paleoanthropologist Richard Leakey and we’re going to hear a lot about his research on human evolution but if you want to read more about it he’s just had a very nice article published in the in the this this times magazine murica so I would strongly recommend that you take a look at that anyway without further ado it gives me great pleasure to welcome mark to present his his lecture the evolution of the human brain mark take a picture my friends right I have to say out an introduction like that unfortunately you know it’s going to be all downhill first thing these are my friends I’m a geek so I don’t get out

much so these are my friends and I will be introducing them through the talk what I want to try and do is tell you about human evolution just give you in about 40 45 minutes some of the exciting new advances we’re making and also why I’m so passionate about this subject so I can’t do it alone I have friends and colleagues from Oxford from Potsdam University from New York and from Berkeley all of whom have actually contributed to this and you also see there is a helicopter we’ll come back to the helicopter later right right so our earliest ancestor we think was sort of like a guerrilla type that occurred about six to seven million years ago in Chad and we think that because of the gorillas like features we had this sort of adaptation to forest however this is where the fossils were found so we already know that there have been profound changes in African climate over the last six to seven million years and that for me is where the stories start how has this climate change influence us and allows you to understand speech and have that huge brain that allows you to watch Coronation Street and I will come back to Coronation Street so bipedalism came first and I’m sorry I have to do this joke Lucy is not my ex-girlfriend and I did have a girlfriend called Lucy I promise you I did and again this was a revolution when this was found by Dawn Johansson because it showed that we started to walk up light first so our ability to do this on stage and walk and as supermodels do okay that was because of our locking knee and these are the first eight and Lucy comes up to here on my hip and this is Lucy small brains slightly bigger than in chimpanzee and it is I’m really sorry even though I have these in my office it is very tempting occasionally – okay you’re very welcome to play with these later and do the same okay so this is Lucy and so the first question is why why did we start to walk up like why was that more exciting than actually using your fists as chimpanzees along the ground now the key thing is about East Africa is its tectonic Lee really really fun because everything changes and we know that the Rift Valley starts about 20 million years up in Ethiopia and we start to have that doming and we have this splitting and the way I described it in the Eureka magazine is it’s a bit like your apple pie it rises in the middle and unfortunate if you cook it a bit too lot too much it cuts in the middle and you have a crack and that literally is the Rift Valley and so if we have a look this is central Kenya and you can see these huge grab ins they’ve actually been forced up and even in the inner rift this is a huge thrust and uplift and just give you some scale that’s our Jeep okay so a fairly tectonic active and I would say that almost everything has changed in East Africa and so what happens is about 20 million years ago we have a hot spot underneath East Africa and you get that sort of doming that heating up and pushing up this starts the apple pie effect you start getting some cracking and that’s where you start to get the Rift Valley forming and then much later it forms a big plateau and this is something I stress a lot it’s called a valley but it’s hanging a thousand feet up to 2,000 feet above sea level so it’s not a valley really it’s hanging between in two major mountain ranges and what effect it has is that moisture in East Africa comes from the Congo and comes from the Indian Ocean but when you start to build these huge mountain ranges what happens is the rain gets concentrated in rain shadows on either side and then finally you start to actually block the rain from getting in to the Rift Valley so the Rift Valley then starts to dry out the other thing I put on the right-hand side is the fin later jet you find that you have a mountain range nearly one and a half miles high which then acts like a racing track wind comes along off the Indian Ocean hits that spins round and spins off and takes all that moisture off to India and the monsoonal system so the effects on vegetation are quite clear so you have nice wooded Africa and then

unfortunately we have some savanna and then much more open territory so the idea the savanna hypothesis is that our ancestors the chimpanzee which we split from about six to seven million years ago quite happy in the forest quite happy surviving the fort and then a bipedal ancestor like Arthur Pittacus ramidus about four and a half million years ago found that this open landscape is fragmented landscape meant that being able to move distances efficiently was actually a good evolutionary trait and this is something that I point out to my students even the ones with a hangover which is you can walk all day you can travel a huge amount of distance by pedaling if you imagine trying to do it on your knuckles etc it’s incredibly tiring so this is an efficient locomotion for an ape to actually travel large distances and so people think that actually that ability to move around between different food sources was absolutely essential as the vegetation in East Africa started to fragment but the thing that I’m really really interested in is big brains so the key thing is firstly walking upright came first and then we got bigger brains and you can see that from about five million years to go to about two and a half million years ago if you measure the brain capacity it stage very similar and it’s only slightly more than a chimpanzee okay so we haven’t really got particularly smart and then there’s this huge jump about 101 point eight million years ago there’s a jump and we jump to this which is Homo erectus and this I once described him if he was walking down the street in a three-piece suit you go rugby player okay you wouldn’t say that’s an alien species and so very much by that period of time we have something that hasn’t quite got our brain size but really does look part from the very heavy brow ridges hence the rugby player joke and then the next jump comes about a million years ago we jump up to a bigger brain and what’s interesting is that this is slightly split from the species because Homo habilis the first Homo occurs here and it’s actually quite a small increase and this is this is Homo habilis and according to the experts okay this one is bigger than this one right well again the interesting thing is it’s when things were discovered because this one was discovered by Louis Leakey with stone tools this was the great leap forward and so this was made a prominent new species it’s Homo this is the ancestry of man the interesting thing is had we found Homo erectus first that’s clearly so there’s a bit of politics particularly in anthropology Richard Leakey when I’ve heard him talk he unfortunately lost his legs when he was flying people believe that his airplane was sabotage when he was running the Kenyan Wildlife Service and he steps up on the stage and he’s incredibly charismatic and he go and he hits his legs so everybody knows their force and he goes do you know what it’s great to be back in paleoanthropology but I still think it’s more dangerous than Kenyan politics so so hence why a lot of the paleontologists don’t like me because I’m just a climatologist what do I know about human evolution right so for many years from about the mid 1990s the aridity hypothesis dominated the whole idea of human evolution and so the idea that Peter Dominica in Lemont in Columbia University came up with he said look here we have for four million years global climate cooling down we have the big ice ages coming in and we know from isotopes that actually is getting more grassland in East Africa and then he said and actually this is the dust record this is the dust so this is the dust blowing off Africa that you can see this is the Sahara this is a huge dust plume and you can find that in ocean cause and he said look here’s the dust record and actually you can see that there are steps in that data I have to say I’ve tried with a few pints of alcohol I can’t see it and I have to say friends of mine Martin have done some stats on it and this whole myth of steps and aridity is a myth it doesn’t exist they aren’t there so this wonderful paper in science in 1995 just doesn’t

have what it says it has so Martin and I started this in 2003 and I have to explain that we were stuck in a conference on the Amazon in Tucson Arizona okay don’t worry that’s what scientists do they go to veil places to talk about other odd places and and he basically was sitting in a talk and I have to say some of my colleagues as I’m sure you’re aware aren’t particularly good speakers and so a bit dull and so we were writing notes to each other like naughty school words like the people at the back there we weren’t writing noting do you want to do work in Africa yes I do that’ll be great fantastic and hence the whole of this study came from naughty schoolboys writing notes but we decided actually the ocean cause don’t tell you what’s happening in the Rift Valley and that’s where all the fossils are and that’s where we evolved so why don’t we go there and find out what’s happening and so this is exactly what we’ve done we’ve done about five field seasons in the Rift Valley and I have to say you have to fly up there and the helicopter helicopter is just a glorified taxi okay it takes exactly six days after which you stop taking photos of it but again it’s incredible for fieldwork because what usually happens is you get in your 4×4 you drive for two and a half hours to the actual site you get out it’s midday already the heat has really started to hit upper 30s lower 40s you do an hour or two you get back in your four by four helicopters fantastic you can be on site just after dawn so as soon as dawn comes up you fly you’re on the site at seven o’clock in the morning you suddenly realize that after two hours of working here this is a rubbish site so you call up the helicopter move to the next one so incredibly practical way of doing field work in the 21st century but what I want to show you is this is the Sakura Valley in northern Kenya and this is a wave-cut platform and so what we’ve done is we’ve gone and found lots of lake sediments and seeing where they are in relation to the rest of the actual environment and measured shorelines and it gives us an incredible powerful tool so these are all the lake basins from Lake Malawi all the way up to a fir that we’ve been working on and this is a blow-up of sort of the current lakes in Kenya from the Vasa from bearing go all the way up to Lake Turkana where was a couple of weeks ago and you had these beautiful beautiful sort of sediments so this is carrying dizzy so this is white sediment it looks like the White Cliffs of Dover and actually it’s made up of silica diatoms which are small single-celled organisms that use silica to build their shells instead of calcium carbonate but they’re incredibly informative because each species tells you how fresh the lake was and how deep it was because they all have a particular preference so this is dated about a million years ago and so we have at least three lakes or curl at the same time then this is Lake cushaw dated about 1.7 million years this is Martin looking very cool and that’s one of my PhD students and they mined this stuff in Kenya I’m not going to ask this audience but many of you may have soft drinks many of you may drink Coca Cola I’m not sure I’m allowed to mention that um you won’t realize that it is filtered for all its impurities honestly they have impurities and it’s actually this stuff so there’s a whole mining going on as you can see in the background of this dynamite which is then heated up and then used as a fantastic filter for soft drinks they are a lovely side issue nothing to a human evolution right and you can see here these lakes occur about two million years ago and then this is boring go where we have a set of five lakes on top of each other with as soils in between showing how the climates varied and we have to at about two and a half million years so we came to this problem so these are all the basins so this is the south this is Otto vie all the way up to afar in Ethiopia and so we suddenly found that these lakes all occur at about the same time and when species of early humans were changing and so we suddenly realized that we had these lakes when Peter said that it was dry like Oh how do we do this without getting ourselves into real trouble and so you can see we can put all these lakes together and so what I’ve done is just compress that all into when do lakes occur in East Africa and you can see they’re beautifully cyclic four and a half for three and a half three two and a half to one etc through this period of time and I’m just going to

pick this period of time here for you to focus on almost all the lake basins in East Africa are full of fresh water at this point in time and we can do species is a diversity so these are how many species of hominids so how many of these guys were running around together in East Africa at the same time and there is a point here about two million years ago that we have about six different species that we know of hominids running around and so you can put this all together and start looking so we have low levels of brain here and then we have this massive brain expansion here massive speciation and huge amounts of Lakes occurring in East Africa and I’ve also put these lines on these lines of win hominids actually left Africa this one is when we went into South Africa these are when we actually went into Europe and you Asia and it means that the migration patterns of hominids also a driven by these lake occurrences so when the actual basin fills up it’s actually no space for hominids and they get pushed to the south and push to the north so did human evolution occur in the Garden of Eden were we surrounded drinking cocktails round beautiful fresh lakes no the story is a little bit more interesting than that and actually it’s because both Peter and we are both right so these lakes actually are ephemeral they actually occur in sets of four or five and these lakes come and go they’re not permanent features of the landscape which actually is the key to understanding why our brains are so large and this is because of the wobble okay the earth actually wobbles unfortunately on its axis now we’ve known about this for many years and we understand that this is how the big ice ages our wax and wane on long timescales but what we hand appreciated is the wobble called precession which actually affects the seasons has a huge effects in the tropics so the way to understand precession is if you have a spinning top as we all did as kids you spin it and you let it go and it spins round and round around but what you also notice is the axis the plunger you’ve at she pushed also wobbles around but much slower and in the case of the earth the earth goes around once every day and actually this precession of the axis wobbles around a whole circuit once every 20,000 years but what it does is it changes where the seasons are so the present December is actually closest to the Sun but actually remember it’s the tilt of the earth that causes the seasons go back 5,000 years ago September’s closest and then 11,000 years junus and what we found was that you can track these back this is where you actually talk to the physicists and the solar physicists because they do all the wonderful gravitational calculations to work out the wobbles and these wobbles go back in time eight million years plus and actually has a huge effect on the amount of sunlight so the top curve is insulation for the 21st of March on the equator the way I sum this up is say I have a student really really annoying okay I give them a Lux meter that basically measures sunlight stick them at the equator and send them in a time machine back every single day back eight million years and what they record is the amount of sunlight is that curve there and it shows you have a huge variation an amount of seasonal sunlight you get at the equator and you can put this into models to actually work out what effect it has and this one shows you if you have an ice age compared with the modern you shift the rainfall patterns between the hemispheres if you do this with precession modern and precession in the past you do exactly the same so just that little wobble and that change in seasonality in the tropics has the same effect on rainfall as actually having an ice age this is a very powerful tool to actually change rainfall in East Africa so it seems that precession this twenty thousand year heartbeat of tropical climate can change from Eden to hell very very quickly and for me the excitement was now we actually have an understanding of these lakes and this changeable environment how did this actually occur and one other piece of evidence that we’ve been doing is we’ve been looking at Lake scooter and so this is Lately Gibby’s up there it’s a rather smelly alkaline Lake which is about

three four meters deep but we know that only nine thousand years ago and that’s in our integration or in the last ice age but in the last interglacial the whole of this area was full of fresh water 300 meters deep of water and so this is Lake scooter as it is now and this is hyper-arid these are sand dunes I apologize these lines here I couldn’t work out what they were firstly I had these visions of giant snakes however it turns out that the rich boys and girls from Nairobi fly up in their helicopters get dropped off from a hovering and they sand surf down these so I should have just airbrushed the mouth and died right so we’ve done the Paleo shorelines for about seven to eight thousand years ago and that is where the lake was on that mountain range so the whole of this valley was actually full of fresh water so we have this incredible environment that allows huge fluctuations in fresh water and what we did then was saying we’ll hang on how does this actually work how would this drive human evolution there’s so many different views on how evolution works and so we said hang on is it because you have the actual lakes appearing and it’s that high energy you have lots of resources allows hominids to compete with each other and with different organisms is that the cause and then there’s this Peters view which is it’s the high stretch dry period and this is where another bit of the story comes in some of you may be wondering why I’ve I’ve left him all alone right as you can see he’s not very smart okay his brain is actually smaller than your certificate now the interesting thing is look at that jaw okay so at about 1.8 million years this also evolves so there seems to be two different strategies going eat anything think you’re way out of trouble okay so there’s two different strategies going on and so people have suggested perhaps I didn’t mean to insult you but it always goes wrong with me so here we have dry periods so is it the dry period driving this species to actually get that bigger draw so they can use the tubers and dig up any food that they have and then there’s Rick Potts that suggested it’s this variability extreme variability that actually means that you have to plan the future you have to actually try and understand how to adapt to a vapid changing environment my PhD student Cathy Wilson has done some brilliant work on the lakes and what she’s found is by looking at the lake sediments the lakes appear incredibly rapidly they literally just appear in the geological record bang we think that we’re talking about less than a hundred years for that valley to go from being dry to being full of a freshwater leg and this actually makes the evolutionists happy because actually yes evolution works on the individuals do you survive but to actually pass on a trait you need generation a couple of generations of stress to be able to pass this on she also sees that actually getting rid of the lake actually is very jagged and actually the lake shrinks expand shrinks expands and then finally death-knell it disappears and so we now have some real feel for the timing and how much timing these lakes would have curd so it means that early human evolution occurred in an environment with climate change on the human time scale and so we can really start to put that together so I’m going to try and conclude and I’ll try and put some flesh on the skulls first thing is the tectonics in East Africa is incredibly important because everything changes you go from flat tropical rainforest to random bits of savanna mountain forest rainforest the whole works you find everything in that environment the other thing the tectonics does is it produces these basins these isolated basins which are Martin’s called amplifier basins because any change in the rainfall is slightly up or down is amplified by these basins allowing them to fill up or empty very quickly producing this stress

of Lakes coming and going and these Lakes we think we can show our link to speciation so the diversity of our ancestors we can link them to brain expansion particularly at 1.8 million years when Homo erectus appears on the scene that seems to occur with almost all the Rift Valley was actually having huge lakes then disappearing huge lakes and then disappearing the lakes appear in less than a hundred years and I think that is a huge step forward in our understanding instead of just arm waving and going oh look climate changes it might have affect us we can have a real feel that actual climate was changing on a timescale that would influence whether you actually survived and whether your children survived the next year or the next decade Lakes disappearing highly variable and again I think it’s interesting that there are two as I said two ways out you either eat your way out or you think your way out I think the most important thing is that this thinking your way out is actually linked to our survival and warming Dunbar who will be talking later this week and I do encourage you to go to his talk because he is absolute fantastic he argues and this is why I’m going to come back to Coronation Street is that it’s the social brain it’s the ability for us to work in teams to be able to provide food for others who had knowledge but may not be able to actually participate in food gathering that ability to accumulate culture and knowledge to be able to ask questions such as hang on when the lake last disappeared where do we go and get food and that ability to adapt to the environment and for me that’s incredibly important that ability to adapt is hardwired into us if you don’t believe me I dig it out my pocket 30 odd years ago we had no idea what this is okay but my children can do things on this that I can’t okay and so the adaptability of our species and the ability to be a social organism even by telephone Facebook and things like that has actually shown our ability to change and I’m going to leave this with my photograph of my sunsets my beautiful sunsets my love of Kenya in East Africa and to leave you with the thought that if we would truly born out of climate change and our ability to deal with natural climate change and think our way out isn’t it true that we are smart enough to actually be able to deal with our own generated climate change in the future thank you very much okay mark that’s great thank you very much and so I’m supposed to add a sense of organization to this very sort of coordinating questions so I’m sure there are plenty of questions so gentleman here with the glasses yeah microphones will come around so just wait until they appear you talk as if it all took place in the Rift Valley I was is that true or was them was there also stress in other places in Africa because I was reading Chris Stringer’s book and he talks he talks about gives the impression that there were sort of clumps of humans fleeing all over the four corners of Africa looking for I think he calls them refugia when had the impression that was a lot of winnowing out that went out you know extinctions and so on and and variability outside the Rift Valley is that true right that’s a fantastic question the first thing is to say I might have been a bit mean about Osteopathic oh sorry honest you’re absolutely right this creature was all the way in Africa so I was in North Africa and it was in South Africa and so it was continental wide and actually very successful what we think we found is that new species so the new species when they appear they only seem to appear in East Africa you then find them later in South Africa we think that’s their migration you find them in North Africa and then later on when you get Homo erectus you find them in Damini sea in southern Russia and all the way through to Indonesia and so what we think and of course we’re always beholden on the fossil finds and there’s always surprises out there is we think that the new species actually appear in East Africa and then actually are leaving either out of the Rift Valley and then actually from about two and a half sorry

1.8 million years onwards actually even leave Africa so I hope that answers your question anybody else please call out it’s right over there behind a pillar yeah yeah that’s what’s called the yellow room hi if um if this variability in climate it gave us bigger jaws and bigger brains what does the future projected variability in climate droughts and floods gonna do to us right that’s the future of evolution now again I have to tell you you should go and see Mark Thomas who is a colleague of mine at UCL who’s also talking who’s a geneticist who does actually talk about future evolution we are continuing to evolve okay the interesting thing is some of the fantastic stuff coming out of genetics now and ancient DNA show that light skin only occurred 15,000 years ago lactose tolerance the ability to actually have the enzyme to actually process milk which I know that which has also worked on is only about 7,000 years old so our bodies and our species is still starting to evolve the interesting thing though the idea you’re actually going to get a new species suddenly appearing unfortunately we are a huge weed we cover every single continent except Antarctica and there are seven billion of us so actually producing an evolutionary pulse that changes our physical form in a huge way is unlikely but you do get lots of small micro changes that are occurring all the time would it would it be true to say that the future drivers on our evolution are probably going to become more social than than perhaps environmental which is what you were saying no I I think that they will be environmental but I think there will be much more things like how do our bodies adapt to antibiotics how do we adapt to more resilient strains of malaria how do we actually deal with certain diseases so I think there’s a lots of adaptation that’s going to occur and then passed on I think anybody else somewhere who did fire the control of fire and the control of cooking have a much of an influence on our brain size right this fire is a tricky question not because we don’t want to know but it’s very difficult to find in the record and actually prove it’s not a natural fire so the last and this is two weeks ago the last paper we saw that we actually trust the data that looks very good puts fire at occurring 1.4 million years ago so after Homo erectus but somewhere in that brain expansion period and so we think that is when we had the first evidence the problem is that absence of evidence before that doesn’t mean fire wasn’t there what people have said is important is meat-eating through this period and particularly with Homo erectus is incredibly important so it doesn’t matter if it’s raw meat the high energy cost because as colleagues of mine point out having this big brain is actually a real downer firstly actually infant and mother mortality rates in humans are much higher than other mammals ok because it’s a really stupid system you’re trying to get this huge concrete melon as my wife pointed out to come out and then you have this completely helpless infant for three years before it can actually survive so meat-eating and the huge by the way 20% of all your calories just goes on that brain which is hardwired into understanding soap operas ok but it is it’s true if you think about it most of the time and this is very true of scientists you do a lot of gossiping you don’t know you do but you do ok and so most of our time is about social interactions it’s how we actually navigate our way through the world is actually understanding people’s facial expressions and how people then talk to each other and what mean dumb are says actually the reason for the huge brain is that sort of interact so so Richard and I are talking here and pretend you’re not here okay we’re talking and we suddenly start talking about a colleague of ours now I have to work out does Richard like this colleague or doesn’t here you know so I yeah what do you think about John or John’s okay yeah yeah fine yeah yeah but he dissed my paper oh why okay okay and then we can also go further we can actually talk about John and his relationship with the woman over there okay so we can now start talking and we

can go to five levels if you ever look at a Shakespeare play the amount of duplicity we’re really good at this by the way duplicity goes very very deep about five different levels that you can actually calm people okay we’re very good about and that’s actually what Robin says is why we have that big brain building those social groups and working as teams takes a lot of brainpower Jung come here when you say the lakes declined in a hundred years he’s suggesting that the population crashed and essentially got very high variability coming forward or what did the evolutionary impetus come from the uncertainty in the lakes to later date right I think and this is only my opinion it firstly the lakes appear in a hundred years and actually the variability is about on the same scale but they do this when they go for me it’s about resources it’s actually whether the resources suddenly appear or disappear and it’s that we move I my favorite view is it’s the removal of the actual resources at the end of the lake and which is most important the interesting thing is when you fill up the Rift Valley with the lake you suddenly get forests growing everywhere all up the Rift Valley so actually it’s a really difficult place for a bipedal hominid to actually live and so really we then get shoved out and it’s only when the lakes not shrink that it becomes a nice place to actually go along the shorelines and actually most of these species are found in Lake shoreline and riverine deposits that actually trapped them so my feeling is it’s that removal or stress or food that has that driving force that says how we’re actually going to get that food sources and quite a few of these do go extinct at the same time as these appear if Homo erectus evolved into us could the acceleration of climate change and destruction of habitat caused chimpanzees or other Apes to default evolved into a subspecies oh dear chimpanzees you’ve been watching Planet of the Apes haven’t you I I can tell the problem is that the climate change that we’re looking at which is over the next hundred years in evolutionary terms is actually quite a small period of time one of the key things I think is important with these periods of variability is you get hit a number of times so you get a lake coming and going a lake coming going and you’re doing this four or five times in succession over about a hundred thousand years whereas I think that the climate change that we’re going to experience over the next hundred years has already influenced lots of species and some of them have gone extinct some of them will have to change their pattern of behavior but actually I think chimpanzees as long as we protect them will be fine so um you may find this a bit facetious and I just wondering you talk about twenty percent of the calories they needed for our brains um instead of going for a walk every day could I put my feet up and do a couple of super fiendish Seleucus no because unfortunately it’s actually not a seizures question the problem is idling your brain doing nothing when we think we’re doing nothing and actually saying doing Sudoku actually the difference in calories is zero actually just having the brain it’s like having a really nice sports car but you’ve got it constantly running okay and occasionally you do rev it up but actually the amount of energy difference between that and just running it all the time is very small so that’s a great question but no unfortunately I do suggest everybody goes to for walks and we everybody does Sudoku please how much is brain size a factor in the tool-making aspect of hope yes fantastic question and I’m going to swear you all to secrecy um this is interesting because of course Homo habilis was named man the toolmaker okay and that’s why habilis is his name because stone tools were found with the skull and the species is pushed back to about 2.4 million years because a bit of a jaw which seems to be this species and stone tools are found at 2.4 so this is the tool maker unfortunately or fortunately because I think this is the great thing about paleoanthropology rigidly he and his group have found stone tools which are much older so

we’re talking and you’re sworn to secrecy if there’s anybody from nature here don’t talk to them 3.2 million years so it means that our little ancestor here who is about this height was using stone tools because this is why I talk about the social brain using tools is actually not that clever chimpanzees do it they’re quite a few birds that do it so the interesting thing is if that stone tool use is passed on from generation to generation now that is an interesting thing but no it means that we’re pushing back stone tool use back to before homo actually appeared which I think it’s very exciting it’s a great question but don’t anybody answer there’s one really aus we’ve still got plenty of time for more questions so don’t hold back I don’t this is children because I’m not gonna hold back on it I’m always intrigued how much you can tell from a few fossils could you give us an idea how many complete skulls or bits of skulls or bits of jaw you reckon right okay the the estimate is and that anything prior to modern anatomical human so before Homo Sapien we have about 250 bits of different bodies and so that’s very form almost the complete skeleton of Lucy two bits of jawbone or the skull you saw right at the beginning so it’s about 250 bits for skulls actually those points I had on the graph is all we have where we have enough of the skull to estimate the volume and that’s why there’s some big gaps in the record so we know the species appear say about two and a half million years but we have no way of estimating their brain size so I would say that reduces it down to about forty data points for skulls so not a very good record sorry oh we don’t and we don’t and this is why you have to be very careful when we say ancestor actually there could be one that we’ve never found which actually led to homo erectus from chimpanzee and so we know these are ancestors or lineages that are related to hominids and will be we are related to them but actually saying well this one led to this one they led to this one two doesn’t work at all you’re absolutely right oh sorry hi I was just wondering how much for old genetics plays in in the story of evolution or at all I don’t know it in terms of using that as an analysis tool um can you what do you mean by using genetics give me a bit more to work with and I don’t really know um I mean analysis of ancient DNA yeah that kind of thing looking at yeah genetic objects for instance or the DNA stuff is incredible at the moment we are exploding and knowledge on that and literally this is the new frontier unfortunately Richard and I are just now all hat you know the it’s the geneticists are taking off the some of the stuff that they’ve done looking at say Neanderthal DNA being able to sequence large chunks with to see similarities between Europeans Africans and the anatole incredible changes and that understanding of how recent some of our adaptations so yes we’re homo sapien yes we can go back about a hundred eighty thousand years as a species but many of these features blonde hair light skin and things like that and lactose tolerance and things that are incredibly recent in less than say the last fifteen thousand years so genetics are giving us lots and lots of information and for me that’s where the new frontier is unfortunately so if you go and see mark Thomas’s talk yes he will tell you lots more exciting things he’s actually in conversation with Marcus bird stock which will be great fun a comedian and Mark can be grateful but these types of materials they go out of if if we’re talking about analyzing for ancient DNA these unfortunately go out of the sort of window of what we currently understand as being the the window in which DNA survives in the in the paleontological record about a hundred thousand years is sort of thought as being the window so but never say never there’s some incredible things happening but the other thing that the geneticists are doing is they’re using our own genome to actually look through to see where there are particular adaptations the one thing which I found out and you I found amazing things I just sat there for a whole week in Kenya going really Wow

why that doubt did you know that all of you still have an ensign inside your stomach that means that you can eat insects okay you can actually process which again the number of enzymes that come and go in a population a huge but actually almost every single human being on this planet can eat insects and survive they’re not so different from shrimp serve other well yes it should gentleman at the front here oh sorry yeah we talked about the young eeveelution to site and the growth of the size of the brain but do we know anything about the size of different components of the brain and how they might have been important for examples was the visual cortex more important than with the brain you’ve got emotion and social interactivity no it’s a simple answer you can people have tried with incredible three-dimensional cat scans to actually look at the actual imprint of the brain inside the skull and try to estimate the sizes of different parts that is not as successful as you would like and really doesn’t give you a handle on the cheat is actually we look at the artifacts so we look at what have our ancestors left behind do we have pottery do we have jewelry do we have symbolism and again that’s when we start to build up this view of culture and when culture CH came in so unfortunately the brains don’t read or the brain the skulls don’t really give us enough information some people try to look for much smaller bones and one thing that is interesting which is unfortunately not quite culture the teeth give us a lot of information so Chris Dean at UCL has looked at the teeth and you can see growth lines in the teeth and what he finds is this species is born grows adult this species grows adult don’t know about that one homo erectus grows Plateau and that’s called teenage okay preteens okay yet we have about four or five years because evolution decided to torture us and then the growth and so there’s an interesting growth Plateau that occurred one and a half one and a half million years ago as some adaptation to the environment and so that that’s an interesting thing why would you want to have a growth plateau is that because you need an extra four years of moody teenagers to actually imprint them with some knowledge of how to survive in the African plains and so there’s lots of interesting ideas so that gives us an idea of how the brain is developing but actually unfortunate inside is not that much information lady towards the back of the front row her hand up whereabouts do you think you’re most likely to find more very very ancient skulls so what are the most promising sites caves or desert you know right that’s the question that all paleoanthropologists don’t talk about and won’t tell anybody it’s like Shh I have to say for me the most important site for all of this is to karna and the interesting thing about Lake Turkana and this is why Richard Leakey set up his Institute there was that it has a geological record going back to 65 million years ago and so it’s interesting that you can actually trace lots of changes all the way through and this is where those new stone tools that you haven’t heard about have been found at three and a 3.2 million years ago and actually for me that’s where we’re going to find lot more exciting skulls if we’re going to find them but it’s incredibly labor at and time-consuming pastime and you it’s also a bit of luck there are some people that just have that vision that can see a piece of bone in the dust are sticking out and it’s that and a bit of luck but for me too Carter and with Richard Leakey actually trying to build that Institute there and using it as a base to try and protect that area and that’s fantastic so that would be my answer is to Conor is there any so to say a bit more about what type of deposit Oh what does it leave these these sorts of human remains are found in are they mostly münster most of them are found in soft what were soft Lake deposits riverine deposits and cave deposits so one of the most surprising things in the last 10 years was finding Homer florensis over in Indonesia which basically was about this size but at

you have the body of this one which is quite odd and being only 15,000 years so there seems to be a remnant a pygmy remnant of Homo erectus somewhere in Indonesia and we found them in cave deposits and so they had been going into the cave dying and actually then building up in the sediment but the African ones are mainly in lake and river silts which has been a solidified okay I think we did one more quick gone wicket vi1 one or two more questions we can you missed him Oh Oh gentlemen over here sorry with the dark top on see you shouldn’t gone for the last one who’s going to ask a really mean question I can tell I was I just wanted can you tell if they can swim lots of lakes around will they swimmers um if you’re going to talk about the aquatic ape theory we’re going to have a talk later no idea absolutely no idea there is no reason why Homo erectus could not swim I have no idea about the others but you find that chimpanzees can actually wade they don’t do swimming very well but they can wade through water and you see them standing up like this wading through lakes so these would have been quite happy wading through lakes and this one the other thing I should have mentioned about Homo erectus and Richard would tell me off for wasting time but here he also is running man the interesting thing is Dan Lieberman in Harvard has done an analysis for Homo erectus and there’s lots of really exciting things from your tendons to the way your neck works all means that we can run and all of you if I trained you for a year could run a mouth them it’s quite interesting that actually it’s not it’s something that’s quite natural that humans can run a mouth on which is bizarre but and if you ever don’t believe me go out and you find that when you walk your head does this when you run your head stays exactly level because of all the way your shoulders and everything is fixed your head stays exactly like that when you’re running just so you can make sure you find that there was one more question the lady just in front of the pillow there you’ve mentioned lactose tolerance couple times presumably as they were mammals they were they were all lactose tolerant when they were born is it something that they lost and having lost it and and we haven’t got it why have we got it why did we suddenly decide we wanted to go on drinking milk beyond infancy do you want to answer that one yeah the quote the question is really one of it’s not lactose tolerance which we all are up until at the time we were weaned from mothers milk the question is the lactase persistence gene which appears to evolved once we started to to consume ruminant milk then we had to then in later life have the gene available that we could still process the lactose which is would otherwise be toxic to us so it’s that the question is essentially which we all have the lactase digestive capacity but it’s actually whether that digestive capacity actually extends into later life as it does in most of the people in this room I guess and it must have had a very strong selection so the interesting thing is that it’s found firstly about seven eight thousand years ago in central Germany and that seems to have them radiate out radiated out into bits of Africa and bits of Europe which has just got a paper coming out in nature shows that milk was actually on pottery pottery area in West Africa seven thousand seven thousand but it’s the key thing is that those that weren’t lack so tolerant were the ones that actually died out and therefore there must be a very strong drive to actually allow those that had that extra bit and we would process milk through the bad years to actually survive when the others didn’t it’s a little bit like the Scandinavians have an incredible sort of drive to have blonde hair and light skin because of course they could actually absorb much more sunlight allow them to actually produce and a so they didn’t get rickets and so it’s an incredibly strong selection this is why all Scandinavians are incredibly fair-skinned because anybody who didn’t have fair skin got rickets and died and this is unfortunately how evolution works it’s about sort of like the survival of those that have that extra little bit of edge and this guy and you guys all have that edge and that’s something I do point out I’m going to end with this so which it doesn’t have to wrap up is one thing I will point out to you is all of you are incredible

because all of you are survivors every one of you is from a lineage of brilliant survivors all the way from the first bacteria well done guys all the way through you survived the dinosaurs you survived the extinction you survived all of this and your parents got it together and you survived that and therefore all of you are incredible evolutionary survival stories well done you