Totem And Taboo.
A year later, Sigmund Freud was to suggest in Totem and Taboo (1913) that totemism was the expression of a psychological, rather than social, reality. His theory was predicated on the link between totemism and exogamy, which Freud took to be a manifestation of the horror of incest. He was also profoundly inspired by Robertson Smith's hypothesis of the ritual sacrifice and consumption of the totem animal. However, he incorporated these ideas into an original scenario of his own. Humanity, he suggested, once lived in primal hordes where the father monopolized all the women and exerted tyrannical authority over his children. His sons eventually conspired to kill him, eat him, and take his place. However, the guilt that they experienced not only prevented them from mating with their mother and sisters but ultimately caused them to institute a prohibition on incest.
Psychoanalysis has revealed to us that the totem animal is really a substitute for the father, and this really explains the contradiction that it is usually forbidden to kill the totem animal, that the killing of it results in a holiday and that the animal is killed and yet mourned. The ambivalent emotional attitude which to-day still marks the father complex in our children and so often continues into adult life also extended to the father substitute of the totem animal. (p. 182)
For Freud, parallels between the behavior of "primitives" and "neurotics" led him to seek explanations of both phenomena in terms of his understanding of universal unconscious emotional processes.