When did "nodding" your head come to mean "yes" and...?

No clue...very nice question! I tried googling and came up with this cool link/site, in regards to cultures and signs,etc.

http://www.straightdope.com/columns/read/619/why-d...

Star for you! ;-)

And this one....... https://www.greenpassion.org/index.php?/topic/1049...

Nodding Head

that was decided during the council of trent. many cardinals and bishops argued over this, it was a month long symposium. The countryside was sorely taxed, taking care of the personal needs of these great men. Several were executed in the process but in the end, nodding came to mean "yes" and the side to side motion came to mean "no".

The extent of conviction was indicated by the vigorousness of the movement. If someone asked you if you wanted cream in your coffee, and you did, you were supposed to bob your head up and down rapidly, even VIOLENTLY at least eight times.

"There are varying theories as to why nodding is so frequently used to mean "yes". One simple theory is that it is a form of bowing, indicating that one is prepared to accept what another person is saying or requesting. It has also been stated[1] that babies, when hungry, search for their mother's milk by moving their heads vertically, but decline milk by turning their head from side to side." (Wikipedia)

Various researchers also indicate that the custom of "nodding" (in agreement) and "shaking the head" (in disagreement) is common in many cultures.

I agree that this method of communication may have begun in the garden of Eden.

I think nodding is naturally connected to accepting because you're somehow putting your head below the other person in front of you. And being down is connected to less power, up for more power, more energy, as laws of gravity say. The Wolf that is up is the powerful one, because he has gravity on his side.

As for the case of "no" it seems that comes as a contrast to the previous explanation, a counterpart to nodding. You're deviating your face from the person in front of you like directing it towards other people or places, meaning that you agree with other realities, not the one expressed by that person. Or creating some kind of barrier of air before him/her.

This is as old as human kind. A mother breast fed her child and in this suckling a child nods it's head yes. Imagine this before you come to a conclusion. Now when a baby was crying and it was not hungry what would the baby do when their mother tried to put them on tit? Yup the would smack it away and shake their heads no. Globally a nod always means yes and a shake always means no. Makes no difference what language is spoken.

It just started when someone wanted to end the subject quickly and go on to something they would rather talk about, or they didn't want anyone to hear them say yes. Sometimes it's a lot quicker and it avoids further discussion maybe?

For your info, that in India it is the other way round, when they nod their head they mean NO, and when they shake their head they mean Yes.

When Eve took a bite of the forbidden fruit, she looked at Adam and nodded and Adam was looking at her shaking his head. Well you know the rest, the girl won that one lol

The nodding yes and no is learned as a baby to find the nipple of your moms breast.

Later on we continue using it but as yes and no signs.