For decades, scientists thought that most primates could not produce vowels, sounds fundamental to human speech. That’s because nonhumans supposedly lacked the necessary vocal anatomy. But now, researchers report that Guinea baboons, monkeys that inhabit the forests and savanna of West Africa, make five vowellike sounds similar to those used by humans. The findings bolster a recent study showing that Japanese macaques are also anatomically capable of speech. Together, the work suggests that the basic elements of spoken language began to evolve much earlier than suspected, at least 25 million years ago.