A look at how and why some species die out, with an emphasis on the extinction resistance of others. Though the Alvarez theory, that the demise of the dinosaurs may have been affected by a fall of meteors, is still scientifically suspect, Raup (statistical paleontology, U. of Chicago) figures he may as well be hung for a cow as for a calf, and argues that all extinction of species are at least partly caused by meteors. The thought that even the fittest...