Primates are unquestionably clever: Monkeys can learn how to use money, and chimpanzees have a knack for game theory. But no one has ever taught a nonhuman primate to say “hello.”

Scientists have long been intrigued by the failure of primates to talk like us. Understanding the reasons may offer clues to how our own ancestors evolved full-blown speech, one of our most powerful adaptations.

On Friday, a team of researchers reported that monkeys have a vocal tract capable of human speech. They argue that other primates can’t talk because they lack the right wiring in their brains.

“A monkey’s vocal tract would be perfectly adequate to produce hundreds, thousands of words,” said W. Tecumseh Fitch, a cognitive scientist at the University of Vienna and a co-author of the new study.