We have very little actual knowledge of pre-historic humans to speculate about their sexual behaviours (and as with all other human behavior, I'm sure there is and has been great variance in this).
In any case bonobos would not write Kama Sutra even in 20,000 years. Your timescale and argument is way off.
In any case bonobos would not write Kama Sutra even in 20,000 years. Your timescale and argument is way off.
Downvoters: I've no more apples for you.