Nature is fairly parsimonious, especially with complicated things like neurological structures. Once you've built something, and 'you' being evolution, once a neurological structure is in place, it's very difficult to undo that and replace it with something else. Expensive. And life doesn't really stop to give you a chance to re-plumb the depths of the way our brains are structured. And I'm... When I say our, I mean, life on earth. Vertebrate life, let's say. But... So, what nature seems to do is to... As our brains evolve, we take a system, and then develop a new system that, sort of, wraps around it, and integrates with it on a... To a certain extent, but it's not a deep, complete reworking. In a sense, we have two operating systems working now. We started with one, and now there's another one, and they talk to each other, but it's sometimes problematical. And then along comes another layer. And to overly simplify it, we have what might be called the reptilian brain, and wrapped around that, the mammalian cortex, and wrapped around that, the neocortex, the human primate brain. And roughly speaking, these would be instinct, emotion and logic. And each one of those brains is capable, under the right circumstances, of taking over the situation.

If you're in a desperate situation where your life hangs in the balance, pretty much the instinctual brain will take over, because you can't afford time to think about things. You have to really act instinctively, without emotion, sometimes, and maybe without logic. You just have to react and hope for the best. There are other times in completely different situations where emotion... Where instinct has to be overridden by emotion, and that's... One of the main values of emotion is that it acts as a, let's call it, a clutch that separates out the gears of instinct, and allows a certain amount of flexibility in our reactions. That, if we are emotional, and I mean that in the largest sense of the word, we are not so tied to obeying our instincts, we have a little more flexibility and difference of response.

And that is a way of defining what mammals are, because mammals nurture their young. Reptiles, in general, do not. They lay eggs, and then abandon the eggs to whatever life will afford to them. There are some exceptions to that, and they're notable. But in general, the reptilian response to reproduction is: you're on your own, kid. And reptiles are born fairly, very quickly, functional in the world. They're weak and vulnerable, but they're able to function. And now it's up to chance and how many predators are in the neighbourhood, whether they survive or not. But the parents are not there to help them so much.

With mammals, and to a certain extent, I would include birds with this, there is this element of nurturing, and what makes nurturing possible is emotion. And I'm going to say that there's no question that the mammalian animal, and even the bird... Not even, the birds, have some emotional connection with their youth, their kids, because they're expending a tremendous amount of energy trying to make sure that these are not... that they have the best chance in the world, even after they're born. I'm going to support you up to a point where you're able to fly on your own, let's say. And... Or I'm going to suckle you and give you milk for... I'm going to eat, turn that food into milk, and suckle you to nourish you. On a certain objective level, why should I even care about that? You're something different from me. But there is a bonding there, and that bonding is something that... Let's call it 'emotion'.

On top of that is something that is predominantly human, but we can see it in... We can glimpse it in other primates, and even in other animals, and even, to a certain extent, in birds, and it's working things out logically. So that we're not responding instinctively, and we're not responding emotionally, but we are looking at the situation, saying, 'What's the best solution to this problem?' How can I work this out? Language is a big element in that. And language, even if we don't speak to other people, the language with which we talk to ourselves is something that helps us to work problems out.