I want to talk to you today about the evolution of the brain. And in particular, of course, the evolution of the human brain. Although we will talk about some other brains as well. You may recall from way back in the beginning of the course, when I talked to you first about Darwin and his whole saga of trying to figure out when and how to publish his big idea about evolution. And the one thing that made him wait to publish that more than anything else was his realization that he couldn't leave the brain out of that formula. That it was also a product of this same evolutionary process. Here's a quote from one of his books. He says why is the thought being a secretion of the brain, I love that. Secretion of the brain. Why is thought being a secretion of the brain, more wonderful than gravity, a property of matter? It's our arrogance and admiration of ourselves. He said that it's just the way things are. And it's not more or less factual than the information that we have about gravity, and the planets, and all the other physical, chemical sciences. But, it's a difficult concept for people to deal with and we've talked about this several times already during the course. There seems to be a great need for something else. There seems to be a great need to have some sort of a spiritual, non-physical element to go along with it that we don't always see the richness of just the biological fact of our brains and how they work. I want to begin by giving you, I don't think Dennett calls it this but I call it Dennett's creed, he has written probably his most famous book relating to this course would be his book called Breaking the Spell where he really delves into great philosophical detail and he's, I have to say, one of the very few philosophers that I find easy to read. He really does have a sharp mind and a good way of presenting the information. But he deals with this throughout the book, but the one quote that really caught my attention was his response to the question, how can we live a good life and a rewarding life if we don't believe in these non-physical types of things. This is what he said. I'm going to read it as well. He said, if you can approach the world's complexities, both its glories and its horrors, with an attitude of humble curiosity, acknowledging that however deeply you have seen, you have only just scratched the surface, you will find worlds within worlds, beauties you could not heretofore imagine, and your own mundane preoccupations will shrink to proper size. He means small there. For if you can stay centered and engaged, you will find the hard choices easier, the right words will come to you when you need them, and you will indeed be a better person. That, I propose, is the secret to spirituality, and it has nothing at all to do with believing in an immortal soul, or in anything supernatural. So that's kind of his central point. It's his rock in the stream where all the other ideas flow around it and he defends that rock very vigorously in his writings and as you've seen in his discussions on videos and everything so, he's done a lot of thinking about this. And a lot of thinking about how we can survive quite nicely in a world where we understand how the world works around it. And this has certainly been something that's been in the news recently, relating to the election. And in some very real sense, a lot of the things that happened in the past election was a return to some evidence-based thinking about these things, and a rejection of some of the anti-science things. Certainly a lot of other things were involved as well, but that's one of the things that has been a recurring topic in the post-election analysis. And we're all sick of election and post-election by now. But it's an important national discussion that we have. [COUGH] Well what I want to do today is to scratch the surface a little bit of brain evolution and try to walk you through what seem to be some of the important aspects of human brain evolution. Now, here's what we're going to do. We're going to talk about three major themes as we go through the lecture. And professor Solomon has talked about this. I've talked about a little, about the mediocrity of the physical human being. We're not very fast, compared to a lot of animals. Our visual system, although pretty good and probably one of our best sensory systems, does not compare favorably with the visual system of an eagle. Auditory system, and so on and so forth. We're just always in the middle and it's very easy to go out and find another species that can best us in almost any aspect of our behavior or our abilities to perceive the world around us. But what we're going to see is how the evolution of the human brain has given us leverage of these systems. And in some sense, we'll see that our sensory systems have given up, in a way, some of their basic capabilities out in the periphery. In exchange for the much more powerful interpretation centered within the brain. Professor Ogilvie talked a while back about the progressive emergence of more and more complicated selfs. I struggled for a while about whether to call it selfs or selves. Just kind of like people have struggled with whether that little thing that you use for your computer, if you have more than one of them, are they mouses or mice? And I think they finally decided that. They're supposed to be mouses so that gave me the courage to call them selfs. But we'll see that human evolution has given us the time that is needed for these very complex things to develop. So one of the things we're going to be talking about is the very long childhood that humans have that give us the opportunity to develop the self's and a lot of other things as well. Professor Oglevee also also talked about the power of cuteness awhile back. And, strangely enough, we're going to see that cuteness is also an important theme of human evolution. And the particular thing that we'll be talking about is something that is known as neoteny, N-E-O-T-E-N-Y. So let's start out by looking at some of the results of evolutionary processes in other creatures. I'm going to show you several different creatures here and ask you to give me some ideas about what you think are the special adaptations of these creatures. So let's begin with the muskrat. What's a special adaptation that the muskrat might have? Yes. >> Being able to blend in with is surroundings, like the [INAUDIBLE] >> Okay, blending into the surrounding, special camouflage. That works, anything else? >> Ability to swim? >> Ability to swim. That's good if you're going to be a muskrat, and they're great swimmers, so, a couple of examples there. Okay, let's move on to the squirrel. Adaptations of the squirrel. Come on guys, you can do it. >> Able to climb trees. >> Able to climb trees, yes. >> They store nuts, and dig them out, and they'll take [INAUDIBLE]. >> Yeah, they can store nuts, and then they take them off and bury them, and maybe even remember where they buried them after that, so, yes. >> Avoid cars! >> They're not very good at that. [LAUGH] Mallard duck. Yes. Webbed feet for swimming. >> Feathers to keep them warm. Feathers are actually kind of oily, too, so they're well adapted to the water. Yeah, way back there. >> They can fly. >> They can fly yes. >> Pileated Wood Pecker. >> Sharp beak. >> Sharp beak, anything else? Actually the pileated wood pecker is kind of cool. They have special muscle structures so they don't get concussions when they're pecking on the tree. The egret. Anybody have a, okay go ahead. Long neck. >> Long neck. That's good for giving it perspective. Alex. >> Long legs. >> Long legs, good for wading in the water. I saw one a while back, a few years ago wading out into a river and it waded into some deep water and swam away. And I was shocked, I had never even considered whether they can swim or not. But obviously you have to be able to swim if you spend your life wading around in water. Here's one that you may not know. What do you think the special adaptations of the woodcock might be? Yes? >> Camouflage? >> Camouflage, they're awfully hard to see. Anything else? Notice, it might even be hard to see because of camouflage, but its beak starts here and ends here. Big long beak, they stick that down in the ground and bring up worms and larvae and things like that as a part of their diet. So all, very good ideas and things about special adaptations, but you missed the big one. You missed the big adaptation that they all have in common. Brains. Of course they have to have brains, but each one of these creatures with their sometimes amazing physical adaptations. Those physical adaptations wouldn't be worth squat if they didn't have some special area in their brain that controlled the behavior associated with that adaptation. So the squirrel has to be able to find nuts and store them and all of these other creatures have to have specialized brain areas that allow them to use these physical adaptations. So this is a coordinated thing that happens that we don't just have physical adaptation going on and behavioral adaptation going on. They work very much hand in hand in the evolutionary process and what we're going to see is a human brain evolution is especially good at that. So, behavior is often over looked, but it's probably the single most important adaptation that any complicated creatures might have. So we're going to be talking a little bit about building a brain. And for all of his fussing and fretting about it, Charles Darwin didn't even really mention the brain and behavior until the very end of The Origin of Species where he gave it one sentence. And he said psychology will be securely based on the necessary acquirement of each mental power and capacity by gradation. Not that different from what he was talking about physically, but he's saying that we have to have the evolution of all the individual components of behavior that ultimately go into the huge complexity of human behavior. A hundred years or so later a couple of other neuroscientists had a long and complicated article in a review journal. And one of the things they said was that the main neuronal circuits achieve an architecture that is breathtaking in its complexity, but frugal in its variability. Breathtaking in its complexity but frugal in its variability. So the breathtaking in complexity part, which we'll spend a bit of time on. The brain is just an amazingly complicated structure and whether you're looking at it with the naked eye and then with a dissecting scope and then with a regular microscope, and eventually electron microscope, you just keep seeing more and more complexity as you delve into the structure of the brain. The frugal and variability part means, essentially, that we can have the discipline of neuroanatomy. So your brain looks a lot like my brain and both of those brains look a lot like this plastic model of the brain here, and in the same way that it's possible to look at a skeleton and name the bones of the skeleton, you can then look at somebody else's bones and it will be easy to apply those labels to somebody else's skeleton. And the same thing is true of brains that there's a commonality amongst brains so that you can go in and label the hippocampus and the amygdala and all sorts of other Latin named structures within the brain. And apply those same names to somebody else's brain. But, as we'll see when you look at the details of the brain, if we went in and looked at the substructure of the individual connections within the brain, then your brain would not look like my brain. And you would probably be grateful for that because if your brain looked exactly like my brain, you would think like I do and how bad would that be? Pretty bad. So how do we go about building a human brain? Like everything else, it starts out with a blueprint. And that blueprint of course is the DNA. And that provides the building instructions for the brain. Mostly, the building instructions for the frugal and variability part of the brain. It's just building the basic structure of the brain, and when we look at the embryology of the developing human, we see just how important this building of the brain is. Of course, you all know that we start out with a mommy and a daddy loving each other very much and all that kind of stuff. And we end up then with the cells coming together, and they begin to divide, multiply, and after a fairly short period of time, you end up with a little ball of cells that looks a lot like a tiny little soccer ball. It's something that you would probably not quite be able to see with the naked eye. You'd probably need at least a dissecting microscope to see that. But already, important things are beginning to happen. And if you were to take a soccer ball that didn't have quite enough air in it, and give it a little karate chop, it would make a groove on the top of the soccer ball. And that's pretty much what the human embryo looks like in the very, very early stages where you could quite literally count the cells. Have a little groove like that. And this groove is called the neural groove because that is the beginning of the development of the brain. So the absolute first thing that happens to distinguish the embryo to give it some structure beyond just a little ball of cells is the nervous system, the brain that's starting. A little bit later the groove gets deeper, a little bit later than that it actually forms a tube called the neural tube. And that is then the number of cells that are going to form the brain and the spinal cord. Coming over here to this part of the diagram, you see kind of a schematic of the brain, and that tube begins to fold over and get bumps on it and become more and more complicated and sending things out. And that's going to eventually form a very complicated bump, the human brain, at the top end of it and all the other fibers that go out to serve the body. So the nervous system takes precedence in all of this. And at the stage of development where you already have a fairly complicated brain beginning to develop, the rest of the embryo is not developed. There might be tiny little bumps here and here, and here, and here, where arms and legs are just barely beginning to develop, but not much else. So basically, starts with the brain and develops everything out from that.
