The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution

by Richard Dawkins

No evolutionist thinks that modern species change into other modern species. Cats don’t turn into dogs or vice versa. Rather, cats and dogs have evolved from a common ancestor, who lived tens of millions of years ago. If only all the intermediates were still alive, attempting to separate cats from dogs would be a doomed enterprise, as it is with the salamanders and the gulls. Far from being a question of ideal essences, separating cats from dogs turns out to be possible only because of the lucky (from the point of view of the essentialist) fact that the intermediates happen to be dead. Plato might see the irony in the fact that it is actually an imperfection—the sporadic ill-fortune of death—that makes the separation of any one species from another possible. This of course applies to the separation of human beings from our nearest relatives—and, indeed, from our more distant relatives too. In a world of perfect and complete information, fossil information as well as recent, discrete names for animals would become impossible. Instead of discrete names we would need sliding scales, just as the words hot, warm, cool and cold are better replaced by a sliding scale such as Celsius or Fahrenheit.