With roughly ten million people, Papua New Guinea is home to more than one in ten of the world's languages, making it the most linguistically diverse country on Earth. Steep mountains, isolated valleys and dense forests kept communities apart for millennia. Many of these languages have only a few hundred or a few thousand speakers.
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.