For more than 1,500 years, Hebrew was nobody's first language: people prayed, read and wrote in it, but at home they spoke Yiddish, Ladino or Arabic, among others. In the 1880s, Eliezer Ben-Yehuda settled in Jerusalem and raised his son, born in 1882, entirely in Hebrew, coining modern words along the way. Today it is the language of millions of Israelis, a revival unmatched on this scale.
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.