Time to make way for a new idiom—new data shows that having a “memory like an elephant” is not even that extraordinary compared to that of a dolphin.
Dolphins have demonstrated the potential for life-long social memory, according to Jason Bruck, a biologist at the University of Chicago. In his study, Bruck confirmed that dolphins separated for over 20 years could still recognize the signature whistles of their former tank mates.
The first study to look at long-term memory in cetaceans (fancy, biology word for dolphins and whales), Bruck used an audio device to play the whistles of unfamiliar dolphins, mixed in with the signature whistles of former friends and foes, inside dolphin tanks. The memory test was given to 43 dolphins of all ages, looking at their responses at the sounds of familiar calls.
Mixed into Bailey’s tape, was the call of Bailey’s former tank mate, Allie. Bailey and Allie had been tank mates in Florida when they were only 4 and 2, but where since separated and have lived apart for two decades. When Bailey heard the whistle—she responded.
“She came swimming up to the speaker and hung around there for a little while she listened in,” said Bruck to NBC News. He pointed out that dolphins who responded to familiar calls reacted the same as if their old friends were right in front of them.
In his study, Bruck identifies social recognition as a survival benefit: recognizing kin, foes, or even to prevent inbreeding. As a long-lived species that travels long distances, long-term memory would be advantageous for wild dolphins to form a social hierarchy as they re-encounter each other.
This study is another example of the growing evidence that points to high-level cognition and social structure among dolphins. Biologist Vincent Janik has shown that wild dolphins identify each other by signature whistles, or “by name.” Mothers often teach this whistle to their young calves and become a part of the dolphin’s identity.
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