"When American anthropologist Ales Hrdlicka asked in 1927, 'What is the actual, precise, evidence for human evolution that science now possesses, and upon which it bases far-reaching conclusions?' (my emphasis [Lewin's]), he was in fact posing a question that has no answer. Not because there is no evidence for human evolution, but because3 no science works that way. No science-least of all paleoanthropology-is as objecting as Hrdlicka implies here or as is often portrayed in the philosophers' idealized view of science… Smithsonian Report for 1927, pp. 417-32
preconceived ideas shape the progress of all sciences, but nowhere else to the degree that occurs in the search for human origins. And yes, personalities are important in the flow of all sciences, but, again, in the science of man emphatically so. Le Gros has an answer: 'Undoubtedly, one of the main factors responsible of the frequency with which polemics enters into controversies on matters of paleoanthropology is purely an emotional one. It is a fact (which it were well to recognize) that it is extraordinarily difficult to view with complete objectivity the evidence for our own evolutionary origin, no doubt because the problem is such a very personal one.' Ernst Mayr, one of this generation's most prominent evolutionary biologists, concurs: 'Human beings seem quite incapable of speaking about themselves and their history without becoming emotional in one way or another.'"
 Roger Lewin (noted science journalist), Bones of Contention (New York, NY: A Touchstone Book published by Simon & Schuster Inc., 1987), pp. 20-21
Is there really evidence that man descended from the apes?
Human Evolution Stories