Freud, Wilkie and the other chimpanzees peacefully fed and rested in the sun-dappled Tanzanian forest. Mzee Hilali stood next to me, writing notes on the chimpanzees’ behavior, as he had been doing for over 30 years as a field assistant for Jane Goodall’s long-term study at Gombe National Park.
Suddenly, a strange, high-pitched call sounded from where some other chimpanzees were feeding, about a hundred meters from us. Hilali turned to me, and with a little laugh, said, “Nyoka.” This was the Swahili word for “snake.”
Freud climbed down from his tree and walked quickly toward where the call had sounded, with Hilali following close behind. As I slowly made my way through the undergrowth to catch up with them, Hilali called to me: “Chatu!” “Python!”
A glint of snake scales in the vine tangle. (Michael Wilson, CC BY-ND)
When I caught up with Hilali, he was pointing to a tangled mass of leaves and vines on the forest floor. I looked closely – most of the snake lay hidden from view, but the one visible stretch of black and tan scaly hide was too big to be anything but a python.
From years of experience, Mzee Hilali knew instantly that this particular chimp call meant they’d found a snake. Does this mean that chimpanzees have a “word” for snake? Do chimpanzees have a language of their own? I’ve been working with a team of students and Tanzanian field assistants to record and analyze chimpanzee vocalizations in an effort to answer questions like this. Ultimately we hope to learn more about how human language first evolved.
Clues to the origins of language
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.
If some features of chimpanzee communication resemble language, we can study chimpanzees further to find clues for why those features evolved. If chimpanzee communication doesn’t share much in common with human language, then the key steps in language evolution must have occurred after our lineages separated (around 7.9 million years ago) for reasons unique to our human lineage.
Michael Wilson with microphone during his dissertation research in Kibale National Park, Uganda, waiting for the chimp known as Light Brown to vocalize. (Becky Sun, CC BY-ND) Recording in the