In 1817, Laurent Clerc, a Deaf teacher trained at the Paris institute, co-founded America's first school for the deaf with Thomas Gallaudet. French Sign Language blended with local signs to give rise to ASL. As a result, ASL is far closer to French Sign Language than to British Sign Language, which American signers can't readily understand.
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.