In the Middle Ages, Romance dialects were told apart by their word for 'yes'. Around 1305, Dante sorted them into the languages of 'oc', 'oïl' and 'sì'. In northern France, 'oïl', from Latin 'hoc ille', became modern French 'oui'. In the south, 'oc', from Latin 'hoc', gave its name to the 'langue d'oc', Occitan, and to a whole region: the Languedoc.
In Kuşköy, a mountain village in northern Turkey, people talk across valleys by whistling Turkish. A 2015 study showed that whistled Turkish draws on both hemispheres fairly evenly, whereas spoken Turkish relies mostly on the left. The physical form of the signal, it turns out, matters to the brain.
Speech has no gaps between words. In 1996, researchers played 8-month-old babies a continuous stream of made-up syllables for just two minutes. The infants picked out the 'words' by tracking which syllables tend to follow one another. That's probability calculation, done without a calculator or any visible effort.