Humans are very closely related to chimpanzees in evolutionary terms. But why can we talk while they can’t?
Two tiny changes in the sequence of one gene could have helped install the mechanisms of speech and language in humans. The differences could affect how the brain develops, and so explain why only humans are capable of language.
The speech gene is called Foxp2 but it doesn’t control speech all by itself. It actually turns on and off a bunch of other genes, and all together they work to enable human speech. Read more here, here, here or here.