[The selection of sexual partners of different species by mammals]

It appears biologically sensible that every animal seeks its mating partner within its own species. Sexual contact with alien species may occur when animals are isolated from members of their own species, particularly, however, after they have been raised in the environment of alien species. Copulations of this nature do not, as a rule, result in offspring, although an entire series of bastards among closely related species is known. Among domestic animals bastardization is partly planned systematically as this has advantages in comparison to original forms. Sodomy, i.e. interspecific sexual contact between a human being and an animal, was already described in ancient times.