Belgians and French-speaking Swiss say 'septante' for 70 and 'nonante' for 90, more regular than France's 'soixante-dix', sixty-ten, and 'quatre-vingt-dix', four-twenty-ten, and once common in France too. For 80, Belgians say 'quatre-vingts', four twenties, like the French, but the Swiss cantons of Vaud, Valais and Fribourg say 'huitante'. Three neighbouring countries, three ways to count to a hundred.
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.