In 1887, eye doctor Ludwik Zamenhof published in Warsaw a language designed to be neutral and easy, under the pen name 'Doktoro Esperanto', 'the doctor who hopes'. The name stuck. More than a century later, Esperanto has its 'denaskuloj': children raised in it from the cradle, often born to couples who met through the language. Their number is estimated at one or two thousand.
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.