Babies just a few days old can tell English from Japanese, two languages with very different rhythms, even when recordings are filtered to keep only the melody. English and Dutch, which share a similar beat, leave them unmoved. Long before understanding a single word, an infant is tuning in to the music of languages.
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.