How did nodding your head up and down come to be interpreted as “agreement” and nodding side to side as “disagreement” or denial across so many cultures?

Question

How did nodding your head up and down come to be interpreted as “agreement” and nodding side to side as “disagreement” or denial across so many cultures?

In: Other

Answer 1

I’ll throw this in but it is something I read years ago and am not really sure about it.

The nod was used by Egyptian people and the Egyptian people were really really into sun worship. People would move their head up and down to signify yes because the sun is high in summer: summer gives life, is good (yes). They would move their head side to side to imitate the low, horizon hugging winter sun: winter takes life, is bad (no).

I like the theory, but it’s likely BS.