My own prejudices are exactly the opposite of the functionalists': "If you want to understand function, study structure,” I was supposed to have said in my molecular biology days. (I believe I was sailing at the time.) I think that one should approach these problems at all levels, as was done in molecular biology. Classical genetics is, after all, a black-box subject. The important thing was to combine it with biochemistry. In nature hybrid species are usually sterile, but in science the reverse is often true. Hybrid subjects are often astonishingly fertile, whereas if a scientific discipline remains too pure it usually wilts.