Will there be breakthroughs within your lifetime?
You get answers all the time, of course, small answers to big questions. But big breakthroughs, I don't know.
What is the biggest question in biology?
Understanding evolution, how animals and plants and organisms evolved and formed shapes and adapted to different environmental conditions—I think that's fascinating, and we have very good theories, but the exact path is not really very well known. We also don't really know how diversity arises, how we get new species and this enormous diversity in shape and form.
Is that what you're working on now?
Yes, that's much of my research, how you get diversity. When you compare genes from different animals, you find very similar genes in worms and in flies and in humans, and this doesn't really explain how they got different. And I want to know why.
Are you still working with drosophila?
We are now mostly working with zebra fish. There is great variation in fishes, and if we can understand it in fishes then perhaps we can also figure out the differences in mammals. And it's much easier to work with fishes than with mammals.
Why is it easier to work with fish than, say, mice?
Mice are live-bearing, and their embryos are small and you can't look at them. Fish lay clear eggs and you don't have to kill the mother in order to look at the babies, which you have to do in mice.
How many fish do you have right now?
We have about 10,000 aquaria. It's a big house with five rooms. And the total number of fish is probably 500,000.
And do you ever have dreams about the fish?