These Monkeys Have Names for Each Other

Humans aren't the only primates who call each other by name, according to a new study. Researchers say marmosets—a chatty, highly social monkey species that lives in South American rainforests—use specific calls to address specific individuals, behavior only previously observed in humans, bottlenose dolphins, and African elephants.

• "The experiment was very simple," David Omer, lead author of a study published in the journal Science, tells CNN. "We just positioned two marmosets in the same room and positioned a visual barrier between them When you do this they spontaneously start to engage in dialogue."

• Marmosets communicate with chirps, trills, and, when other monkeys are out of sight, whistle-like "phee calls," the Washington Post reports. Omer and his team analyzed more than 50,000 of the calls between pairs of monkeys and found that they contained name-like information about the recipient.
• "We discovered that marmosets use these calls to vocally label their conspecifics," the researchers wrote. "Moreover, they respond more consistently and correctly to calls that are specifically directed at them. Analysis of calls from multiple monkeys revealed that family members use similar calls and acoustic features to label others and perform vocal learning."
• Marmosets are the first non-human primates known to use names, but they aren't very closely related to humans, with the last common ancestor living 35 million years ago, compared to around 6 million for chimpanzees, AFP notes. Omer says the names are likely the result of "convergent evolution," with the marmosets, who live in small family groups and cooperate to raise their young, facing challenges similar to what early humans dealt with.

• "Until now we thought that human language was a big bang phenomenon that happened out of nowhere and only in humans—which is a complete contradiction to evolutionary theory," Omer tells CNN. He says the finding suggests "there were precursors for language development in non-human primates and we can find evidence for an evolutionary process."
• Scientists studying other animals, including prairie dogs, say they're not surprised by research showing that communication systems are more complex than previously thought, the Post reports. George Wittemyer, who was part of the team that recently discovered elephants use names, says the discovery is "really exciting and very amazing." "This story about animals having arbitrary names for objects or each other has been this thing that's so unique and rare in the animal kingdom," he says. "We put our paper out, and three months later there's another species."

(More marmoset stories.)