Cheat? or merely multiple sex partners? The latter doesn't imply the former unless everyone is in a monogamous relationship (which the bonobos aren't, and early humans probably weren't, either).
Just to be a pedant, bonobos aren't monkeys and don't fling their shit.
While I don't think comparisons to our closest living non-human relatives are entirely misplaced, using it as justification for cheating is bullshit. All the bonobos know what's what, your cuckolded partner does not.
Have an open relationship or a series of short relationships, or whatever you want, but be honest about it. Build your relationships on trust and communication (and hot sex), whether open or closed, whether long or short.
tl;dr, don't be a jerk.