okay thank you in Stanley Kubrick's 2001 a Space Odyssey we're treated in the early scenes of this film to a situation that we are told is near the dawn of man and we have what we only assume are our somewhat hairier ancestors hanging around and picking fleas off each other's bottoms and then a large slab of what we seemed like black rock a monolith appears and it makes all kinds of eerie choral sounds and it seemed to put into these ancestors the ability to make tools and from then at least according to this this story it's a relatively short step to space travel and everything else and all you require is a black monolith and a monkey well clearly this is just literature it wasn't actually that simple but we only share a common ancestor with chimpanzees about five or six million years ago and that's remarkably recent and we've done quite a lot in those five or six million years we've come a long way and the archaeological record does tell us something about what's been going on in that intervening time so the first stone tools actually appeared about around 3.3 million years ago and without being disrespectful to our hairier ancestors they really weren't very impressive from about 2.6 million years ago a new tool tradition comes out called the older one tradition and it's still not that impressive they're really just rocks with chipped off points probably used for things like crushing bones to access marrow and so on and then about 1.7 million years ago we get a somewhat bigger jump so we see the appearance of a type of tool known as by faces so these are taking much more f to make their they often have this teardrop shape and they're much more beautiful and then that lasts for about another 1.4 million years until we get a period called the middle Paleolithic where the tools get a little bit more impressive so we have half tin and things like that and that lasts for another two hundred thousand years so over that period of about 3.1 million years I think it would be fair to say the progress was modest then around or at least over the last hundred thousand years we get an explosion an explosion in technology so we often refer to this as the Upper Paleolithic transition sometimes it's called the late Stone Age a many archaeologists and anthropologists have referred to it as the origins of modern human behavior so we see many new things we see much more fine stone tools much like hobby knife so much smaller micro lifts they're called we see the first use of things like bone and antler to make tools we see body decoration in the form of ochre to cover the skin threaded shells and ostrich ostrich egg shell and so on basically we see the beginnings of bling and these people they love their bling and we see the first musical instruments and also we see well we see the beginnings of pornography as well but most impressively by a long way we see the first realistic art and we see the first abstract art as well and when you look at some of this art this isn't a monkey just doodling something kind of on a cave wall this stuff is seriously impressive and I would challenge you to look at this and denied that the makers of this art didn't think or didn't have the same basic human capacities and cognitive capacities that we have today now this has been happening over the last hundred thousand years and over that period there are at least five different species of humans around so there's us anatomically modern humans there's a species called Denisova which we know very little about what they look like because we only have a few finger bones and teeth but we do know a lot about them because we've managed to get a whole genome from those finger bones and teeth and so we can say a lot about how they're related to us and how they've evolved also there was Neanderthals which of course everybody knows about there were these Homo erectus or often called the hobbits that lived in Islands South East Asia tiny little brains and Homo erectus which lived over quite a long period of time but towards this latter period were found more in eastern Asia so which of these guys was and gals was was producing this modern human behavior well we definitely know that we were we definitely well could be reasonably confident that homo forensics these hobbits weren't I mean their brains are tiny there's no evidence that Homo erectus was but we really don't know about Denisovans and the and ourselves and some people have argued the answers were on their own trajectory towards a modern human behavior now one of the interesting things about this transition this explosion in technology is that it doesn't happen when modern humans our species arrived in different places he does in Europe but in most places we're around for a while before it appears and sometimes as a long delay and it first appears in southern Africa between seventy and a hundred thousand years ago and there are a number of sites down there in South Africa but one particular site called blombo's cave which is very famous which has the first abstract art or representation that we found in the archaeological record it has things like bone needles it has bling and many of the other features of modern human behavior but this kind of behavior appears earliest in Africa and then it disappears and then it comes back in Europe it arrives when we arrive but in other parts of the world we arrive and then often there's a 10 20 30 even 40,000 year gap before you see this flourishing of modern human behavior so what can be causing it well one obvious thing of course is our break big fat brains that we're so proud of but in fact that doesn't seem to work so our brains have been increasing in size over the last two and a half million years and they've they've more than trebled in size over that period but over that period of time when that trebling went on there was really very modest increases in our technological complexity so the point at which we get this explosion in modern human behavior if anything our brains have actually got a little bit smaller which is somewhat embarrassing and in fact in fact that throws out a big question because why on earth would you want to involve a big brain so from an evil it's easy to save from now you know with the benefit of hindsight and what we do with them but from an evolutionary point of view it's a pretty stupid idea to grow a big brain for a number of reasons so firstly what we tried to kill our mothers when we're born so up to 30% of adult female mortality in hunter-gatherer populations is down to childbirth and any woman here who's given birth will testify that there are issues when you've give birth the battlefield also our brain it's only about two-and-a-half percent of our body mass but it consumes up to 25 percent of our energy budget it's a breathtakingly energetically greedy organ and what's more it's incredibly fussy so many tissues can use all different types of sources of energy our brain just wants glucose it doesn't want anything else it uses up to 60% of our blood glucose and it's a massive drain on our resources you may think your brain is thinking what's he talking about or I think worth therefore I am or something like that it's not your brain is mostly thinking I want glucose can I have some glucose please spare some change for some glucose really wants the stuff also if you've got a big brain that takes a long time to grow which means it takes a long time to meet to get to sexual maturation and what that means is you spend a smaller proportion of your life being reproductively active from an eeveelution point of view that is a dumb dumb dumb idea also as our brains have got bigger our skulls have kind of ballooned much like blowing up a balloon there's a consequence they got thinner and that leaves our skulls on our brains less protected so if you took a heavy iron bar and you hit a similarly sized animal to us like a pig on the head I mean okay it's not going to like it but it's probably not going to die but if you do that to human there's a good chance it's gonna die okay so brains don't or brain size at least don't seem to explain this this increase in our technological complexity now I'm being a little bit disingenuous because of course it's not just size isn't everything so it could be that so it could be that we that we just had other innovations we kind of had a rewiring of our brain maybe to make us somehow clever in some way or another but of course we mustn't forget culture as well so maybe it's a result of us learning to live together better to cooperate better to coordinate our actions better or maybe of course its environment and we did most of our evolving in a period called the Pleistocene which is a mad climatically I mean the place that the climate just goes up and down up and down really rapidly and there are serious challenges to chasing those those changes are now in our ecology because of those changes our environment so many people have suggested many ideas for why this modern human behavior originated usually it's something called the lines of some new mutation happened it just made us cleverer isn't really very satisfying but I'm going to zoom in on this idea of culture a little bit more so many species have culture chimpanzees have culture crows have culture they're really good at it in fact dolphins have culture and so on and of course we have culture but we are a little bit special those species have culture but with the only species that has cumulative culture that is we're the only species where the amount of information that we learn through cultural transmission from learning from each other and across generations the amount that we have in that information that we hold is greater than could be accumulated by a lifetime of merely learning for yourself and in learning from others in your group okay so we know things that have been worked out long before any of us were born we accumulate culture through time that is the defining feature of our species it's not standing upright or anything like that it's cumulative culture in fact human culture is so important it's our life support system we are non-viable without it now what this means is that we can model how culture evolves culture evolves just like just like genetics and biology evolve you have you have different ideas different skills there's variation they're transmitted by learning and then there's differential survival and two chaps are showing up here Joe Henrique and Rob boy proposed a nice simple model for how you could actually make predictions about how it behaves in populations and they develop this idea of directly biased inaccurate in completely inaccurate learning now that sounds like a mouthful but basically what it means is directly biased is if you want to learn something you tried to learn from somebody who's already good at it so we have a picture here of my daughter she wants to learn the piano she's not going to asked me because I can't play the piano so you actually asked my friend Adrian instead and he because he's he plays it brilliantly that's just common sense everybody does that and in completely inaccurate learning means that when we learn from somebody we usually don't attain their levels of skill but sometimes the clever ones actually surpass the teachers level of skill so it's very basic process but a both process we can actually model in a computer so what we did is we tried to do that and what we've got here in this zone innocent moving image each dot is a group of people about a hundred people and they are learning skills and learning skills with this in completely inaccurate learning learning from the person who's the smartest that's one they can find and then they're doing a bit of migration to other groups and then I've just inflated onto it a surface which shows the local level of skill that all of technology of complexity that they can maintain in these populations and the first thing to note is that it's a very dynamic process but then we can probe this and ask some more interesting questions so if we split a world into a high population density in a low population density world do we get differences in the amount of cultural complexity that we can hold onto and accumulate and the answer is consistently yes every single time under whatever conditions we simulate we always find that more dense populations accumulate more cultural knowledge also we can ask okay let's have the same density of populations but the ones on the left they're migrating more and the ones on the right are migrating as much and again consistently we find under all conditions that when you have more migration you accumulate more knowledge more cultural skills so that may upset some tabloid editors okay so we've got a model to explain why this explosion in technology happen in different places at different times but is there any evidence that it matches with the population densities that were present at the times when these explosions in culture occur well putting my other hats on mainly I'm a geneticist and we can use genetics it's a blunt instrument but we can use it to get some kind of estimate of population sizes through time in the past in different parts of the world so we can then ask the question did this explosion happen in different places in the world when they had the same population density or reach the same population density and the answer is yes so the same population density in Europe 45,000 years ago was the same in southern Africa around a hundred thousand years ago which is when we see it same in Middle East the Middle East and North Africa so it's the same population density this kind of critical threshold at which you see this explosion in different parts of the world now I'm not going to pretend that it's just about population density but what I will say is it's gonna be a part of other things of course you need a big brain to do culture anyway what to do cumulative culture of course environments going to affect it of course as you improve your technologies that's going to improve your survival skills so populations will increase as well there's going to be a feedback but fundamentally population size and density and connectivity is limiting the extent to which we can hold on to ideas and skills and technologies so cultural sophistication including art seems to reflect human interaction copying rather than human intelligence if you find that a little bit of a challenging idea don't argue with me argue with these guys so Pablo Picasso said good artists borrow great artists steal I'll ignore the middle guy but Voltaire who's definitely to be admired so the real originality is nothing but Jude is judicious imitation so it leaves us with a thought now the idea that how success that successful innovation depends more on how connected you are learn how smart you are well that seems just as relevant today as it was fifty to a hundred thousand years ago and it leaves us with a few questions I'm not going to answer these questions I'm just gonna leave them up there for you to think about so big brains came along before complex culture evolution has no foresight whatsoever so clearly we didn't know goal of our big brains to do this complex culture why the hell did we evolve these big brains we've got an hour only appears when there's enough people for copying to be effective so is copying the roots of creativity in art and culture and finally well you'll all be aware population density and connectivity especially is between people is increasing is that gonna make us smarter okay I'll finish there thank you you