After my first five years as being Dean here, and really pretty well been devoted to setting up a new school of biology, of filling it with apparatus and people and students and getting the courses going and so on, it's a pretty heavy job. They gave me a sabbatical term. Well, they didn't actually give it me because I got myself paid elsewhere, but they allowed me to go away for a term, let's leave it like that. And I went to what was called the Committee on Mathematical Biology, in Chicago, for three months, I think. And before I went, I decided that I would revisit this problem of ritualised animal behaviour, and I would do so by seeing whether - I knew there existed a mathematical subject called Game Theory, the Theory of Games, I didn't know what it was about but I just knew it existed I thought, well, I'll teach myself some game theory and I'll see whether it will help with this animal behaviour problem. I ought to mention at this stage, though I'll come back to it, that the thing that had brought this problem back to my mind was a curious manuscript by George Price. At that stage, all I knew was that about a year before I went to Chicago, I think, I'd been sent by Nature a manuscript by this person, George Price - I'd never heard of, on precisely this issue - arguing, correctly, as I believe, that the reason animals do not escalate is that if they did, their opponent might retaliate and there'd be a nasty punch up and they might get hurt. So the argument against attacking somebody is he might hit back. And this was sent by me by Nature to referee, and the only problem was that it was 50 pages long. And I seem to have this fate of getting ideas from other people's manuscripts when I referee them, but I suppose it's unavoidable. Anyway, I wrote to Nature and said 'Look, I think this paper's really jolly interesting. Clearly, you can't publish this, it's too long, but persuade the author to send you an abstract which you can publish, and tell him that if he submits this to The Journal of Theoretical Biology, I feel pretty sure they'll publish it.' And I thought no more about it, I thought, you know, I'd done the job. But although George had argued this in a verbal way, he'd not made any kind of formal proof that this is what would happen. And I thought, well, what I'll do is take this notion of George Price's and see whether I can develop, using game theory, a mathematical model which will show that what he's suggesting actually works. And I went to Chicago, I spent three months there. And the only thing you can say for Chicago is that it's so awful, there's nothing to do there except work. I mean, it really is a frightful place to be. So I worked very hard for three months. And as a matter of fact, the problem turns out to be, once you think about it in the right terms, to be almost trivial.