Why Is Sex Fun?: The Evolution of Human Sexuality is an older title by Jared Diamond that has dropped to £1.99 at Kindle UK.
Diamond is perhaps better known as the author of the Pulitzer Prize-winning
Guns, Germs, and Steel; and of
Collapse; both of which I have read, and really liked (enough to even re-read big chunks of). I haven't read this one, but on to the TBR pile it goes....
link:
https://www.amazon.co.uk/dp/B00IO29XJU