In the 1980s, researchers tried to teach Matata, a female bonobo, to communicate using symbols on a keyboard. She made little progress, but her adopted son Kanzi, who tagged along, began using them spontaneously. He went on to master several hundred symbols and understand many novel spoken sentences, though without building a true grammar.
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.