Nature

08
Aug

Dolphins Remember Voices of Childhood Friends. Do You?

If someone you haven’t spoken to since grade school called you, would you recognize his or her name?

A dolphin would. Two bottlenose dolphins, named Bailey and Allie, lived together in Florida when they were young. More than twenty years ago, they went their separate ways: Allie now lives in Chicago, and Bailey in Bermuda. Recently, when Bailey thought she heard her long lost friend, she got excited and tried to strike up a conversation.

Karen Ravn, writing for Nature News:

Bailey’s recollection of Allie’s name — or more precisely, of her ‘signature whistle’, which functions as a name among dolphins — is the most durable social memory ever recorded for a non-human. Yet it is only one of many data points in a study that found that it is the rule, not the exception, for bottlenose dolphins (Tursiops truncatus) to recognize whistles from their distant past.

dolphin
Dolphins can recognize old friends, even after twenty years apart.

In captivity, dolphins often move from place to place, spending a few years in one aquarium before being relocated to another. Jason Bruck, a biologist at the University of Chicago and author of the study, inferred friendships by determining which dolphins used to live together.

Dolphins use whistles as names: they identify themselves by their own whistle and call to friends by imitating their friend’s whistle. To see if the dolphins recognized each other, Bruck played whistles of unfamiliar dolphins and whistles from old friends. Unfamiliar whistles didn’t appear to mean much to the dolphins, but after hearing a friend’s whistle, they perked up, moving toward the underwater speaker or whistling back. They seemed to remember the personality of their old roommate, too—dominant males sparked females’ interest but stressed out young males.

Bruck is pretty sure that a dolphin’s memory beats his own. Think you’re smarter than a dolphin? Watch this episode of NOVA scienceNOW to find out more about the intelligence of these underwater creatures.