Dolphins have names for each other.
We’ve known for a while that bottlenose dolphins have unique whistles that they often use in big group settings, such as when multiple pods meet. But recent studies suggest these "signature whistles" are also used as identifiers that other dolphins can mimic, as if calling out a name. The dolphin can then respond with its signature whistle, as if to say, "Yes, I’m here!"
These highly-intelligent mammals are migratory—they have no homes they return to, and are often moving. But they do live and move in groups. In order to stick together in the vast oceans, it’s important for them to communicate efficiently with the other members. That's why scientists believe they developed this sort of language.
Dolphins are the only mammal, other than humans, to call each other by name, and thus have the potential to teach us a lot about how we first developed language.
Image: Robert Harding Specialist Stock/Corbis