Old recordings show captive chimps uttering the word, which some scientists believe may offer clues to the origins of human speech.

After analyzing decades-old videos of captive chimpanzees, scientists have concluded that the animals could utter a human word: “mama.”

It’s not exactly the expansive dialogue in this year’s “Kingdom of the Planet of the Apes.” But the finding, published on Thursday in the journal Scientific Reports, may offer some important clues as to how speech evolved. The researchers argue that our common ancestors with chimpanzees had brains already equipped with some of the building blocks needed for talking.

Adriano Lameira, an evolutionary psychologist at the University of Warwick in Britain and one of the authors of the study, said that the ability to speak is perhaps the most important feature that sets us apart from other animals. Talking to each other allowed early humans to cooperate and amass knowledge over generations.

“It is the only trait that explains why we’ve been able to change the face of the earth,” Dr. Lameira said. “We would be an unremarkable ape without it.”

Scientists have long wondered why we can speak and other apes cannot. Beginning in the early 1900s, that curiosity led to a series of odd — and cruel — experiments. A few researchers tried raising apes in their own homes to see if living with humans could lead the young animals to speak.

In 1947, for example, the psychologist Keith Hayes and his wife, Catherine, adopted an infant chimpanzee. They named her Viki, and, when she was five months old, they started teaching her words. After two years of training, the couple later claimed, Viki could say “papa,” “mama,” “up” and “cup.”

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