In Mandarin, 'ma' said on a high, level tone means 'mother'; on a falling tone it means 'to scold'. Tone languages are common: about 42% of the 527 languages sampled by the World Atlas of Language Structures, and some estimates put it above half. They cluster in sub-Saharan Africa, East and Southeast Asia, and Mesoamerica.
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.