In 1777, on his third voyage, explorer James Cook recorded the Tongan word tapu, meaning something sacred and forbidden. It entered English as 'taboo', then spread to French and dozens of other languages. A Polynesian word is now used almost everywhere to talk about the things we don't talk about.
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.