This is a lecture, a little bit longer than usual, on the emotions. One reason why it's a little bit longer than unusual is that I'm going to put the study of emotions in a broader context and use it as a way to introduce some ideas about evolution, how it works, and why it's relevant to psychology. So, we began the course by talking about one of the foundations of modern psychology, which is that the brain is the origin of mental life. We call this The Astonishing Hypothesis, borrowing from the title of Francis Crick. It really is astonishing and violates all sorts of common sense. But this doctrine, also known as the doctrine of physicalism, is now universally agreed. What I want to do now is bring in a second radical idea, one that pairs nicely with the first. This has to do with where the brain comes from. This is what Daniel Dennett has coined Darwin's Dangerous Idea, and what he's talking about is natural selection. Now, for as long as there have been people, we've been interested in evolution of complex things. We've been interested in where complex things come from, and in particular, complex things like us, like humans, and other animals, and plants, the things of nature. There's a common explanation for this that many people have found compelling through history. It's nicely summed up by the brilliant theologian and doctor, William Paley. So, Paley writes, "In crossing a heath, suppose I pitched my foot against a stone, and were asked how the stone came to be there: I might possibly answer, that, for any thing I knew to the contrary, it had lain there forever; nor would it perhaps be very easy to show the absurdity of this answer. But suppose I had found a watch upon the ground, and it should be inquired how the watch happened to be in that place; I should hardly think of the answer which I had before given, that, for anything I knew, the watch might have always been there." Well, why not? Because, as Paley points out, the watch shows great complexity. The watch seems constructed. Then, he goes on to make the argument, and again, he was a doctor, that all human organs, the parts of our body, are just as complicated as a watch. Perhaps, more so. So shouldn't you make the same inference? This is what's classically known as the Argument from Design. Part of Paley's argument is plainly right. It's long been observed, there's a rich parallel between biological structures and the structures made by people, the things that we build. So, take the eye. The eye is surprisingly like a camera. Both have lenses that bend light, and project an image onto a light-sensitive surface behind it, either the film or the retina. Both have a focusing mechanism, a diaphragm that govern amount of incoming light; machine for the camera, muscles for the eye. Both help us get images from the world into another medium, in the case of people into our brains. The big difference is, there's no such thing as a camera as anywhere near as good as the human eye. So, Paley's view is that, well, you see something so articulately beautifully constructed, it seems to cry out for a designer. This is an argument that's been made through history. Cicero for instance, made the same argument. You see this argument in current work in so-called intelligent design, and it has huge explanatory advantages. For one thing, it really does explain where things come from, it explains it in a way we understand. Just as we know where watches come from, now we know where eyes come from. Also I don't want to believe it too obvious, but it's consistent with Scripture. It's consistent with belief in the divine creation of humans and other creatures. But there are also problems with this account, the sorts of problems that I don't want to address from a theological point of view, but just from a sort of standard scientific point of view. So, one of these problems, and it's fairly obvious, is that appealing to a divine creator seems to push back the question. This is particularly vexing from a psychological point of view. We're interested after all in where creatures come from, creatures like us, that can think, understand, plan, and know, and to argue that we're the product of yet another thing that can think and understand, and plan and know. Well, it may be true. It's logically possible we were created by a god, or for that matter aliens. But it does seem to push the question back. Ultimately, we'll want to know where such original creatures come from. Furthermore, there's long been evidence for evolution. Long been evidence as seen in fossils and vestigial characteristics like the human tailbone and goose bumps, and all of the genetic and biological evidence for continuity of other creatures. There's a lot of room for debate over the details of evolution, but that evolution has occurred that we were not created in our current form seems reasonably indisputable. Then, finally, there's poor design. So, for instance our eye has a blind spot, the male urinary system, the urethra goes through the prostate gland instead of around it. This poor design seems incompatible with omnevolent, benevolent, and omnipotent God. It seems that, if you want to say it was created by God, that God is either somewhat incompetent or somewhat sadistic, and that doesn't actually seem like a good move from either biology or theology. But still, for almost all of human history, the argument from design was a really good argument. The biologist Richard Dawkins, at one point said that anybody before Darwin who didn't believe in God was ignorant. It was ignorant of the rich complexity of biological structures and uninterested or unwilling to accept the most natural explanation for them. It may not be perfect, the argument from design, the argument that leads to a creator, but it's the best we had. But of course, Darwin changed all of this. So, Darwin had many accomplishments. He was not, as many people get confused, but he didn't discover evolution. People knew about evolution long before Darwin. Rather, his profound accomplishment was showing how these complex creatures like the parts of our body, and into creatures that have these parts of the body like us, could come from. I kind of agree with Dawkins that this is a discovery equal in importance to the claim that the Earth revolves around the sun and we're not the center of the universe. It's the idea of natural selection outlined in the classic work, Origin of Species. I think there's a case to be made that it's most important idea in the sciences ever. Now, this isn't a course in evolution or evolutionary biology, but just to remind people of the core ideas, and if you want to pursue it. There's also a lot of excellent books on the topic, including Dawkin's own Blind Watchmaker. The core idea is that there's three components. There is random variation. This variation gives rise to differences in survival and reproduction and gets passed on from generation to generation. These three steps taken together will give rise to adaptations, in which animals evolve to become better suited to survive in their world. There's all sorts of examples. A simple example is camouflage. So, you could see animal's capacity to- for some animals to have markings that make them difficult to be seen by other creatures is not an accident. It'd be bizarre to say it's just some weird coincidence. Nor is it divine creation. The Darwinian argument is that some animals just randomly do better at blending into the environment. As a result, those animals do better, they survive and reproduce more. As a result of that, those traits, those genes as we'd call them now, that led to this better blending into environment, gets spread within a population, and then so on and repeat and repeat until you get animals are really good at hiding themselves. In a similar argument, for instance, could be sketched out in terms of the eye. So, a great thing like the eye was not created all at once, but rather is the product of increasing adaptation for the task of sensing the world. In fact, Darwin himself noted that you could look at different animals, and you could reconstruct a pathway from no eye to a fully developed eye. More recently, people have done computational models of this very thing. So, you're now wondering why in the world am I talking about this? Am I here trying to sort of proselytize for evolutionary theory in the middle of an intro psych class? But as we'll see, this connects intimately to the study of psychology, and in particular, to the study of the emotions.