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

by Richard Dawkins

Members of different species cannot, by definition, interbreed with one another, yet surely a child would not be so different from its parents as to be incapable of interbreeding with their kind. Doesn’t this, he wound up, wagging his metaphorical finger in the special way that lawyers, at least in courtroom dramas, have perfected as their own, undermine the whole idea of evolution? That is like saying, ‘When you heat a kettle of cold water, there is no particular moment when the water ceases to be cold and becomes hot, therefore it is impossible to make a cup of tea.’ Since I always try to turn questions in a constructive direction, I told my lawyer about the herring gulls, and I think he was interested. He had insisted on placing individuals firmly in this species or that. He didn’t allow for the possibility that an individual might lie half way between two species, or a tenth of the way from species A to species B. Exactly the same limitation of thought hamstrings the endless debates about exactly when in the development of an embryo it becomes human (and when, by implication, abortion should be regarded as tantamount to murder). It is no use saying to these people that, depending upon the human characteristic that interests you, a foetus can be ‘half human’ or ‘a hundredth human’. ‘Human’, to the qualitative, absolutist mind, is like ‘diamond’. There are no halfway houses. Absolutist minds can be a menace. They cause real misery, human misery. This is what I call the t...