If something lies outside our realm of perception, then how can we know it?

Every human culture uses language.

I would imagine every culture would use language, as without language I highly doubt one could survive on his own. Sitting silently all of your life, you couldn’t do much, and you might encounter the need for social contact. It is impossible to engage in social contact without language, otherwise that would be staring at eachother in an attempt to read another’s mind, and that would be pretty awkward!

A culture or civilisation without language would cease to exist, or perhaps not exist at all. How could it carry on, anyway, if a man and woman would not communicate their need to reproduce?  Even ancient civilisations used language, so the lack of any communication can be ruled out in regards to the Mayans’ mysterious disappearance.