So now that we have been introduced to an ecological approach to cognition, let's use it. We're gonna use it to understand dogs of course, but actually the way that we started to understand dogs better was we were first trying to understand human. We were using the ecological approach to cognition to try to understand human evolution. In the beginning I told you that the big question that I'm interested in is what makes us different from other species, what's the little difference that's the big difference in humans cognitively. And it was that question that then lead us to realize that dogs were doing something really remarkable. So let me introduce you to theory of mind, or the ability to think about the thoughts of others, and it was that work that led us to dogs. Okay, for this lecture what will be most relevant is chapter three in the book, and of course anything in Dognition, but I think especially the communication or the reasoning games might be useful here. Okay, so the challenge of human cognitive evolution. Darwin really saw thinking about human cognitive evolution as one of the greatest challenges for his theory of evolution. And in Descent of Man, which he wrote in 1871, 12 years after the Origin of Species and, really, the Origin of Species dealt with animals and the evolution of animals and plants, and he really avoided humans in the Origin of Species. It wasn't until 12 years later he wrote a book really dealing with humans, and in that book he addresses what he saw the greatest difficulty for his theory, which was human cognition. He says, the greatest difficulty which presents itself, when we are driven to the above conclusion on the origin of man, his evolution through natural selection, is the high standard of intellectual power and moral disposition which he has attained. So we define evolution as a change in allele frequency over time, and of course, Darwin was famous for proposing the mechanism which non random change might occur, which is natural selection. But, the challenge for that was, how could natural selection have produced human cognition, the ultimate challenge he saw for evolutionary theory. So that's a really fun problem to work on, lots of people are. And we've been using Tinbergen's reverse engineering, or using function to predict mechanism. If we think about what the function of human cognition would have been for, we might understand why the mechanisms evolved. So what are the problems that humans evolved to solve? And what are the problems that primates evolved to solve? If we can answer that question, we'll have a lot of insight into Darwin's challenge. And there are really two main categories that humans and primates have to solve. First we have to forage for food, and we have to process it once it's obtained. And we don't, as modern humans, think about it that way, but it wasn't that long ago that this was a day to day thing that you had to worry about. And then the second thing of course is attracting mates, and protecting your offspring. And this is something that I think for most people, if you stop and think about it you can realize yes, okay I might not say it in those terms. But yes, obviously, finding somebody to have a family with and protecting your family is something that is a big challenge, that everyone who's human deals with. Of these categories, if we divide the problem we have to solve into those two things, you know, what is it that's most different? And what we have to face as either primates or humans, in terms problem solving, you know relative to other animals. And what a lot of people have argued Is really, it's the social problems, the second category, things that are relevant to attracting mates, protecting offspring, interacting with others of your own species, competing or cooperating with them to be successful. And that's called the social intelligence hypothesis. And the idea is that really, human cognition and the human, what is human about our species is really going to be the social domain. That what makes us different is how we solve social problems, and that's really where we should focus. That the function of the flexibility we see in our species, cognitively, is really a result of the need to solve really complex social problems that result from being human.