Before bonobo behavior was described within the last couple decades, it was thought that WE were the most sexual of the primates.
Gorillas, chimpanzees, orangutans and gibbons are all quite a bit less sexually active than humans.
The last couple of decades...hmm, after the sexual revolution was searching for "scientific justification", wasn't it?
How con-VEN-ient. /sarc>
Cheers!