The Prehistoric Origins of Modern Sexuality

In Sex At Dawn: The Prehistoric Origins of Modern Sexuality, co-authors Christopher Ryan and Cacilda Jetha take what they call the "standard narrative" of human sexual evolution and re-examine it through a different lens: suggesting that sexual exclusivity was not a part of our ancestor's expectations around relationships. Highlighting research in the fields of primatology, anthropology, evolutionary psychology and biology, Christopher Ryan tells Melody Thomas that monogamy is far from "natural" for our species, and that we'd have a much easier time with it if we went in informed.

Here's the story we've been told:

For as long as humans have existed, men and women have made a trade. He offers her protection, food, shelter and status, and in return she promises to be his "one and only", so he can be sure of his paternity when it comes to her children.

They enter into this bargain despite conflicting biological agendas. Because sperm is metabolically inexpensive, it's in his best interest to spread his seed as far and wide as possible. Because she's facing a long pregnancy, plus breastfeeding and a couple of years with a toddler - it's in her best interest to lock him in.

And there's no escaping it, because it's written into our DNA.

Christopher Ryan, author of Sex At Dawn: "If monogamy were natural to us, it'd be easy."

In Sex At Dawn: The Prehistoric Origins of Modern Sexuality, co-authors Christopher Ryan and Cacilda Jethá; take this story, which they refer to as the "standard narrative of human sexual evolution" and flip it on its head.

Analysing decades of research from the fields of primatology, anthropology, evolutionary psychology and biology, Ryan and Jethá; build a picture of human sexual evolution in which "sexual exclusivity was not really part of our ancestor's expectations around relationships."

Basically - our ancestors were much more sexually promiscuous than the 'standard narrative' has given them credit for, and this appetite for sexual variety, sharing sexual partners in much the same way as other resources were shared, served both to ensure genetically healthy offspring and to reinforce group bonds at a time when social cohesion was incredibly important.

This is how it works for bonobos - the great ape that is one of two closest extant relative to humans, along with the common chimpanzee...

Go to this episode on rnz.co.nz for more details