The only unnatural sex act is that which you cannot perform.

The mammalian record thus confirms our statement that any animal which is not too strongly conditioned by some special sort of experience is capable of respond…

There are some who have questioned the applicability of scientific methods to an investigation of human sexual behavior... as though the dietitian and biochemi…

The impression that infra-human mammals more or less confine themselves to heterosexual activities is a distortion of the fact which appears to have originated…