And they all nod their heads up and down for yes and side-to-side for no. Purely random chance. Purely.
Not all humans do this, even if it's common in the majority of countries. Bulgarians do a short nod up for "no", and a sort of head wobble for yes.
In many parts of the Indian subcontinent a side-to-side head "bobble" is a sort of indeterminate "yes/no/maybe".
Very interesting. I guess that exception sort of "proves the rule" because they have to make videos to explain it.
Regarding free speech and the internet, I don't know if it's been brought up but the Internet and text messaging might have profoundly different effects in very free societies and very censored societies.
Since people can communicate more freely and easily because of these technologies, but governments can also more easily monitor what the people say (via automated searches), the effects will vary profoundly based on how different governments act. In the analog era of the old Soviet block, such as East Germany, the government depended on having people report things they overheard their neighbors say, or had to have an agent listening to a wiretap or bug in real-time. Nowdays such a government could just sit back and collect text messages and e-mails, allowing the discontented members of society to freely and unequivocally incriminate themselves, and then move on to the purges.
It's yet another case where making collective action or industrial production easier could be a good thing or a bad thing, depending on the circumstances. Railroads made it easier to move food, vacationers, or armies. Machine guns made it easier to employ fewer soldiers or kill more people.
If we're hotly debating whether our railroad cars should allow strippers to give lap dances, we're probably in the safe zone.