>> Hi, my name's Kenny Smith, I'm a Reader at the Language Evolution Group at the University of Edinburgh. >> Hi, my name's Dr. Suilin Lavelle, and I'm a Lecturer in Philosophy at the School of Philosophy, Psychology, and Language Science at the University of Edinburgh. We here today because we want to tell you a little bit about human cognition. and in particular how human brains and human cognitive structures evolved. There's a really old debate in philosophy which can be traced back to Plato's Meno dialogues, possibly even earlier. About whether we can have knowledge which isn't learned, or whether all our knowledge comes from our experience of the world. Much later, the philosopher John Locke argued that the mind had to be a blank slate, and that all the knowledge that we have comes from experience, comes from living in the world. And he was challenged by Gottfried Leibniz, who said no, no there have to be some structures. Some kind of knowledge that we have that isn't learned. Now no one takes an extreme view of these positions these days. No one thinks that we have, that all our knowledge isn't learned, or that all our knowledge comes from experience. And what we'd like to talk you through today is how this debate has evolved. I'm going to introduce a view called evolutionary psychology. Which says that we have lots of knowledge which isn't learned. And that we can support this by appeal to theories of natural selection. Then I'll hand over to Kenny. >> And I'm going to focus on social learning and culture. And in particular, I'm going to argue that lots of interesting human behaviors, including really important ones like language, can be explained as a product of culture and cultural evolution. >> Natural selection is a really complex concept. And unfortunately, we don't have time to go through today all the different interpretations of the view. If you'd like to find out more about what natural selection is, you can take a look at some of the further readings at the end of this module. For our purposes though, we're going to think of natural selection as a process of environmental filtering. The environment filters out those organisms which are least suited to living in it. Biologists frequently talk about organisms as having adaptations. Adaptations are physical features or behavioural traits that an organism has as a result of natural selection. In order for a trait to be a product of natural selection, it needs to be the case that the trait is heritable. There also needs to be variation in the population, some organisms which have the trait and some which don't. Finally, a trait needs to be advantageous to the organism's reproductive or survival success in order to count as an adaptation. >> The reason that beavers need physical and behavioral adaptations for living in water is, of course, that they spend a lot of time in the water. While lots of mammals live like this, beavers are unusual in that they create their own wet areas. They build dams which block rivers and expand the wet areas that they like to live in. Dam building in beavers is the product of a suite of physical and behavioural adaptations. They have big, rugged teeth which they use to cut down trees. They can then eat the leaves, bud and bark from the tree. That's what they live on. And they can add the tree trunk to their dam. And they have a damming instinct. They're stimulated to dam by the sound of water running over obstacles. The interesting thing about beavers is that these adaptations are a response to an environment in which they themselves have helped to create and shape. Their various adaptations for living in water are selected for, in part, because they actively change their environment, flooding it. Increasing the area that's under water and increasing the advantages that these adaptations provide. As well as increasing these selection pressures, damming reduces other selective pressures. For instance, flooding large areas where they can forage for food minimizes the time they have to spend out of the water, reducing the danger they face from predators. Like many other species, beavers therefore shape the selective pressures they adapt to their environment but they also change their environment. And therefore change the pressures they adapt to. Later on I'll talk about humans do the same thing but on a much grander scale. >> Some adaptations are easy to spot. Take the mammalian heart for example. In the 16th century, the biologist William Harvey discovered that the heart pumps blood around the body. Biologists now consider the heart to be an adaptation. Those mammals that had hearts that efficiently pumped blood around the body, did better than those mammals that had hearts which were less efficient at pumping blood. So its uncontroversial to think of certain organs in parts of our bodies in adaptive terms. So, how should we understand the evolution of our cognitive capacities? Cognitive traits like the ability to do sums or the ability to read, or even the ability to recognize the face of a loved one. Are much more difficult to determine than something like the valves of a heart. We can look at the physiology of the brain, but that only really tells us a fraction of the story of how our cognitive traits evolved. Moreover, cognitive traits like the ability to do maths, don't leave any mark on the fossil record. So, can we use the same techniques of natural selection and adaptation that we used to understand the evolution of physical and behavioral traits, to understand the evolution of our cognitive traits?