Vanessa Heggie is a historian of science at the University of Cambridge.

..."[A]bsolute rape" is not quite the same as Akin's "legitimate rape". Akin seems to be suggesting that the body suppresses conception or causes a miscarriage, while the earlier [medieval] idea ... relates specifically to the importance of orgasm. Through the medieval and early modern period it was widely thought, by lay people as well as doctors, that women could only conceive if they had an orgasm.

The biological basis for this idea is what the historian Thomas Laqueur has termed the "one sex system". The one sex system suggests that women's reproductive organs are fundamentally based on men's reproductive organs, so the vagina is represented as an inverted penis, the ovaries are testes and so on. Women had "cooler" constitutions, and therefore lacked the heat or force to drive the gonads out of the body, to convert ovaries to testes.

Thinking of the sexual organs as mirrors of each other obviously led to questions about the existence of a female "seed" or ejaculate. There was a disagreement about the roles of male and female seed – did they mingle to create the offspring, or did they contribute different things? Whatever the female seed contributed to conception, it was thought necessary, and so in theory a female orgasm was as important as a male orgasm....