This might be better suited to r/AskAnthropology since it probably predates written history. Also note that this is a cultural thing, lots of cultures use different gestures/head movements for approval and disapproval.

Mods, is it allowed to refer to r/AskAnthropology posts here? It's usually high-quality, but I think they aren't as rigorous as you are. But I'm pretty sure this question has been asked and answered several times over there.