I love this subject matter, Katrina. So cool you wrote about this.

I published a book in 2000 in which I proposed that the first word incorporated as being truly human language (and not just a sound with a meaning) is the word milk.

I knew already from researchers that the word milk was found on all continents with spoken languages. A communal link was seen among many of the specific meaning that words like melk, moulka, malok, etcetera had. They pointed to females (sisters, nieces) or breasts, or to suckling. And to milk of course.

The suckling for milk by a baby can be translated into these three consonants M-L-K.

With the M, we have the mouth pressing down, and while making a sound the M is then the only possible sound available.

With the L, we have a transition from front to back of the mouth. Put a pen in your mouth and try to make a sound. Without scraping the throat, the L is more or less the only sound available, naturally an approximation of the actual movement of milk from front to back.

With the K, we have an approximation of closing off the back of the mouth and representing swallowing the milk.

So, when the baby wanted to suckle, it could have dry-suckled these sounds. From that point on, the Mom could have understood the word the baby 'spoke' and then could have started using it herself.

Naturally, other sounds/words could have been used by then, but with its widespread use in the world, this word will have been a breakthrough in language/understanding sounds.

So cool you like this stuff. Me, too.