Bottlenose Dolphins Can Remember Friends They Haven't Seen in 20 Years

Bottlenose Dolphins

Story at-a-glance -

  • The results of a recent study suggest dolphins may have social memory on a par with humans.
  • After a separation of 20 years or more, captive bottlenose dolphins were able to recognize the signature whistles of long ago dolphin acquaintances.
  • Since dolphins seem capable of complex mental processing, is it possible they might even have their own language?

By Dr. Becker

New research may prove dolphins have the world’s longest social memory – as long or perhaps longer than that of a human.

A new study published in the August issue of the Proceedings of the Royal Society B1, suggests captive bottlenose dolphins can remember the calls of other captive dolphins after a separation of 20 years or more.

Jason Bruck of the University of Chicago, who conducted the study, believes his results show “an animal operating cognitively at a level that’s very consistent with human social memory.”

Dolphins Respond to Recordings of Long Lost Friends

Dolphins develop what are known as signature whistles, which are individual vocal signatures that provide information about them, including sex, size and health status. When one dolphin wants to call another dolphin by “name,” he does so by mimicking the other’s signature whistle.

For his study, Bruck played recordings of unfamiliar dolphins to his target audience and discovered that “dolphins get bored quickly listening to the signature whistles from dolphins they don’t know.” But when he played recordings of the calls of long ago friends, it was a different story.

“When they hear a dolphin they know, they often quickly approach the speaker playing the recording,” Bruck explained. “At times they will hover around, whistle at it, try to get it to whistle back.”

For example, a 24 year-old dolphin named Bailey lived 20 years ago at an exhibit in the Florida Keys with another female dolphin named Allie. When Bruck played Allie’s signature whistle for Bailey, she seemed very excited to hear her old friend and tried to communicate back.

Relationships Among Dolphins Are Long-Lasting and Meaningful

The relationships among dolphins are known to be long-lasting and meaningful. Bruck believes this latest study also suggests dolphins are capable of very complex mental processing. Bruck counts himself among a growing group of researchers who suspect dolphins might even have their own language.

And while it’s clear dolphins use signature whistles similar to the way in which humans use names, Bruck next hopes to discover whether dolphins connect those calls with mental images of the animal to which the whistle belongs.