In 1958, psycholinguist Jean Berko showed children aged 4 to 7 a drawing of a little creature: 'This is a wug. Now there are two of them. There are two…'. Most answered 'wugs', a word they had never heard. Proof that children don't just imitate: they extract the plural rule. It's also why toddlers say 'goed' or 'mouses': they apply the rule where English has an exception.
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.