The notion of prehistoric matriarchy and of its replacement by patriarchy can be linked to the historical "inevitabilities" which the nineteenth century's concept of progress through cultural evolution introduced into anthropology. Friedrich Engels, among others, formed the notion that some primitive peoples did not grasp the link between sexual intercourse and pregnancy. They therefore had no clear notion of paternity, according to this hypothesis; women produced children mysteriously, without necessary links to the man or men they had sex with. When men discovered paternity, according to the hypothesis, they acted to claim power to monopolize women and claim children as their own offspring.
This belief system was the result of errors in early ethnography, which in return was the result of unsophisticated methods of field work. When strangers arrive and start asking where babies come from, the urge to respond imaginatively is hard to resist, as Margaret Mead discovered in Samoa. In fact, while prior to the discovery of egg cells and genetics there have been many different explanations of the mechanics of pregnancy and the relative contributions of either sex, no human group, however primitive, is unaware of the link between intercourse and pregnancy. The fact that each child has a single father has come more recently, however; Greek and Roman writers thought that the seed of two men might both contribute to the character of the child. By the time these mistakes were corrected in anthropology, however, the idea that a matriarchy had once existed had been picked up on in comparative religion and archaeology, and was used as the basis of new hypotheses that were unrelated to the postulated ignorance of primitive people about paternity.