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Four-year old Simon is lost. His mother was in front of him just a moment ago, standing right there next to the grocery-store pyramid of apples, but now she’s gone. He looks past the lemons, the pears, the bananas, but still can’t see her. “Mom?” he cries, hoping she’ll come to his rescue. “Mom? Mom!”

His mother, a few paces ahead, hears his call. Her ears perk up. “Simon?”

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He shouts back. “Mom!” Following his voice, she circles back around to find him.

This grocery-store scene could take place at a park, a zoo, a mall, or almost anywhere else. But it also occurs outside our human realm. In the ocean, bottlenose dolphins and calves whistle to call each other when they’re out of visual contact: Mom calls Junior using his signature whistle, and he echoes it back in acknowledgement. In the Venezuelan jungle, when green-rumped parrotlets and their offspring get separated, they do the same thing as the dolphins.

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While numerous species use signals of one kind or another to communicate—vervet monkeys, for example, make alarm calls to warn about predators, and honey bees use a complicated dance to describe food location and quality—these sorts of messages are innate. Parrotlets, dolphins, and humans on the other hand, actually create their own signature handles—they’re not inborn. “We don’t find this much in other animals,” says Vincent Janik, a biology professor at St. Andrews University. “We have very few examples of learned signals invented for a purpose.”

That purpose, as far as researchers can tell, is to manage animals’ social relationships. Invented, name-like cries occur very rarely in the animal kingdom—yet, remarkably, the creatures that use them are incredibly different from each other. Then again, given that names, and the relationships they help to forge, are the foundation of an individual’s social world, it isn’t surprising that these three unrelated species independently developed them.

For those animals that use them, names play into pretty much every stage of relationship building, from mating to cooperation to higher levels of group dynamics. It starts with an introduction, usually an exchanging of personal labels. Parrotlets offer their signature call when meeting a new peer, dolphins broadcast their signature whistles when passing or joining another group at sea, and humans—typically with a handshake or other gesture—introduce themselves with their respective monikers. For humans, sharing a name establishes initial rapport, and many people report feeling closer to someone who refers to them by name in a conversation, thereby setting the stage for a friendship or a business relationship.

Personal labels can also convey important social information: Just as human children typically bear their parents’ last name, some dolphin calves adopt whistles that are like their mother’s, and parrotlet calls within a family are similar. “Parrots provide a number of contact calls, and those of the youngsters’ tend to be modified versions of calls their parents make,” says Jack W. Bradbury, professor emeritus at Cornell University. The main determinant of their vocal repertoire appears to be upbringing: Fostered parrotlets will adopt calls like their adopted parents’ rather than their genetic ones. “Birds are as close as you get to tabula rasa in nature,” says Bradbury. They’re born with nearly blank slates and adapt quickly to their environment; the signature calls they develop are a reflection of that flexible identity.

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Unlike human names, which aren’t usually unique, parrotlet and dolphin signature calls typically are. “Every call is different, which suggests there is no additional meaning except to signal, ‘This is my identity,’” says Janik. On the other hand, there are almost 45,000 humans named John Smith in the US alone—so we need additional information, like social context or that person’s voice, to figure out who they are.

Sometimes these signature handles change, and that can reflect changes in relationships. For parrotlets, morphing calls are a form of social negotiation, says Bradbury. He and his team discovered that, at first meeting, the birds exchange their signature calls several times. As their relationship unfolds, the similarity of their signals oscillates depending on whether their respective social groups will fuse and, in the event of a fusion, the group’s pecking order.

Name morphing can also indicate animals’ closeness. Take dolphins, for example. “When males form alliances [and] spend all their time with each other, they make their whistles more alike,” Janik says. “They have their own signature whistles, but they become more similar to each other over time.” When humans become close, they may address one another by nicknames (Johnny for Jonathan, Cat for Catherine). Janik says the morphed calls could also be a way of signaling to others that these two individuals have each other’s back. Like teens that adopt a clique name (the Pink Ladies, the Plastics), a shared handle indicates an alliance. “If there’s another dolphin trying to attack or taking female away, two similar whistles could make it immediately clear that these two could cooperate for resource defense,” explains Janik. Forming and identifying close alliances is an important part of navigating the social landscape (just think back to middle school), so the ability to relay this information through signature calls is an advantage in setting up, and thriving in, a complex social world.

But humans’ use of names set us apart from the others in one important way: We use them to talk about people when they’re not present. There are many recorded instances of captive parrots and dolphins learning new words, so researchers know that they’re capable of using sounds that represent objects they can’t see, but they’ve never observed wild animals using names to talk about others they can’t see.

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Such differences can provide clues about our background. The evolutionary history of communication leaves no fossil record, so studying how other animals invent and use names is the closest we can get. Comparing other animal societies’ behavior to our own can shed light on the mix of animal intelligence and environmental pressures that allowed certain species to create names. As scientists continue to decode animals’ vocalizations, we’ll be learning not only about their social worlds, but perhaps our own as well.

Jane C. Hu is a freelance science writer based in Seattle. @jane_c_hu

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