One of the things I do to get interesting problems to work on is to notice something curious that I don't understand and to find out more about it and to find out whether it's understood or not. And the last one I did so far has to do with the origin of agriculture.

I went once on a trip for pleasure. And we went to the coast of France, where they... there are caves which have been... which have pictures drawn in them. 40,000 years ago, human beings in a dark cave drew pictures of the animals that were there. There were about six horseheads, one below the other, so beautifully done. So clearly... horses... so clearly that the man or woman who did the painting understood art. And so you get an idea of what this person was. He was not an ape. He was not half an ape. He was a human being doing beautiful work. So you look at that and you think, okay, these were intelligent people. They had no agriculture. The question then is, when was agriculture invented? Agriculture was invented 11,000 years ago, separately in about four or five places within a span of 2,000 years. So from 33,000, what is this? They weren't apes and they didn't have agriculture. Now, what happened? Why?

But we now have data which gives us information about climate for 40,000, 50,000 years, 60,000 years in ice and that is a continual... it varies at times. At different periods, some of them are 100 years. It's going like that. Some of them are further but we have the whole... it's available to any scientist who wants it. It's this complicated thing, but there are methods of finding out what the frequencies and the variations were, which that guy did because his wife suggested it. But he did it. I don't know how to do those things.

[Q] Your husband?

My husband, yes.

[Q] You did this together?

Yes, this is together. And if you do it you can get for all this time the variation of the climate. And you find that throughout the last – I don't know, we can look up the dates later – it varies very rapidly until 12,000 years ago where it becomes a Holocene, which is flat. Climate doesn't change until yesterday. I don't mean yesterday, I mean it's... there are frightening evidence that we're going back into a period of time when the climate is changing rapidly. It's not determined yet, but there's lots of evidence that it's clobbered again.

This period when the climate got quiet, agriculture developed in various places like China and Middle East and Mexico and so on and so forth. Within a short time, within 1,000 or 2,000 years, but in this... that's a short time. And that, I think, it was a great discovery of ours. And it was just taking two pieces of data, which looked to be totally unconnected and discovered there were important connections between them. It didn't take fancy theories or anything like that.

He used to tell me that 30,000 years ago, human beings were smart, were capable of doing agriculture because they were certainly capable of it if you see those paintings. But they didn't have agriculture for another 20,000 years, which is no small length of time. So there had to be a reason why there was no agriculture. And the reason was... we found in the climate data that we have for that long. So there's nothing complicated or amazing, except that we've got the data. And the data shows the only way you can put those two things together is it really wasn't possible to make agriculture 30,000 years ago, because if you look at the record that we have of the climate, it's too variable. You know, if it's... it's got to be reasonable that the weather is such that if it grew last year that it had some chance of growing 100 years after that, otherwise you can't base a civilization on it.

We've been living in the Holocene with developing civilizations for a long time. But we're having a lot of trouble now. The insects are disappearing. The weather is weird. Now, it has to remain for a long time until we have to understand it yet, but it's quite, to me, quite distressing because we're not trying to do anything about it. We're not trying to hold it. It's not going to hold itself, that the present apparently...

The climate data is obtained from ice, looking at ice. The ice near the poles and near the tops of high mountains is thousands of years old. And it's been... they take borings of it, samples all the way down and keep it cold and take little slices of it and look at the chemistry in the water. And they look at the chemistry very carefully. And it's such a marvelous data set. A lot of work has been put into it and a lot of work is put into understanding why the weather is so strange, because the chemistry of the atmosphere is different than it was. So the whole thing is different. Now, what exactly is going to happen? We don't know but we know that things are happening. Like what I said, the insects are disappearing. That's a new finding.

I could tell you some of the things that are going on, but things are changing so rapidly that I do not have a little list that I can tell you. First of all, for quite a while we've been changing the chemistry in the atmosphere. The climate is becoming unstable as far as I can tell from reading other people's work. And we have no knowledge of why the Holocene has been quiet all this time. And before that, it had for hundreds of thousands of years been much more variable. So this is... We don't have enough information yet, but every couple of months there's some other crazy, strange things. Like last week, the problem was the insects are dying of... The insects are very important because once they pollinate things they... We're just changing everything, and nobody knows why.