Michael Wilson in Smithsonian Magazine:
Chimpanzees are among human beings’ closest living relatives, and they share with us many unusual traits. Like humans, chimps make and use tools; join together in groups to hunt animals like monkeys; defend group territories; and sometimes gang up on and kill their enemies.
One trait that seems to set humans apart from every other species, however, is a fully developed language. Other animals communicate, but only humans appear able to talk about an unlimited variety of topics. Language enables us to make plans, negotiate with and teach one another.
How and why language evolved remains a mystery. Much of the evidence of human evolution comes from fossils, but fossil bones don’t tell us much about soft tissues or the sounds early human ancestors made. Studying the communication patterns of our living relatives can help solve the mystery.