Christopher Ryan (born February 13, 1962) is an American author best known for co-authoring the book Sex at Dawn (2010).
[1] His master's thesis examined differences in specific personality measures between working fashion models and the general public.
[3] In 2010, Ryan and Cacilda Jethá published Sex at Dawn: The Prehistoric Origins of Modern Sexuality.
It contends that having multiple sexual partners was common and accepted in the environment of evolutionary adaptation, since, ostensibly, mobile, self-contained groups of hunter-gatherers were the norm for humans before agriculture led to high-population density.
The book generated a great deal of publicity, while numerous scholars from related academic disciplines—such as anthropology, evolutionary psychology, primatology, biology, and sexology—were critical of its methodology and conclusions, although some have commended its arguments.