World views are social constructions and they channel the search for facts. But facts are found and knowledge progresses, however fitfully.

Mass extinctions may not threaten distant futures, but they are decidedly unpleasant for species caught up in the throes of their power.

I was lucky to wander into evolutionary theory, one of the most exciting and important of all scientific fields. I had never heard of it when I started at a rather tender age; I was simply awed by dinosaurs. I thought paleontologists spent their lives digging up bones and putting them together, never venturing beyond the momentous issue of what connects to what. Then I discovered evolutionary theory. Ever since then, the duality of natural history-richness in particularities and potential union in underlying explanation-has propelled me.

Since we proposed punctuated equilibria to explain trends, it is infuriating to be quoted again and again by creationists-whether through design or stupidity, I do not know-as admitting that the fossil record includes no transitional forms. Transitional forms are generally lacking at the species level, but they are abundant between larger groups.

Evolution is a process of constant branching and expansion.

It has become, in my view, a bit too trendy to regard the acceptance of death as something tantamount to intrinsic dignity. Of course I agree with the preacher of Ecclesiastes that there is a time to love and a time to die - and when my skein runs out I hope to face the end calmly and in my own way. For most situations, however, I prefer the more martial view that death is the ultimate enemy - and I find nothing reproachable in those who rage mightily against the dying of the light.

Anything, even the conceptually most complex material, can be written for general audiences without any dumbing down. Of course you have to explain things carefully. This goes back to Galileo, who wrote his great books as dialogues in Italian, not as treatises in Latin. And to Darwin, who wrote The Origin of Species for general readers. I think a lot of people pick up Darwin's book and assume it must be a popular version of some technical monograph, but there is no technical monograph. That's what he wrote. So what I'm doing is part of a great humanistic tradition.