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Dolphins Recognize Each Other After 20 Years Apart, Study Finds


We’ve known for a long time that elephants to have an impressive memory, but some new research is showing that dolphins have the unique ability to remember each other’s signature calls for at least 20 years, making it the longest memory of any mammal.

The study, conducted by researcher Jason Bruck and published in the journal Proceedings of the Royal Society B, found that each dolphin has a unique whistle that is even more recognizable to other dolphins than human facial features are to other humans. While our features change over time, a dolphin’s signature call remains the same throughout its life.

Bruck recorded and collected the signature whistles of 53 bottlenose dolphins living in six different facilities around the world. The dolphins are part of a captive-breeding program and many have spent time together at one point or another. Bruck started by playing signature whistles of a stranger that a dolphin had never heard before, which would eventually result in the dolphin getting bored of the sound of a dolphin it had never met. When the call of a dolphin they once knew played, he said they would often approach the speaker and whistle in response.

“This research shows that dolphins have the potential for lifelong memory for each other regardless of relatedness, sex or duration of association. This is the first study to show that social recognition can last for at least 20 years in a nonhuman species,” he said. He added that this shows animals “operating cognitively at a level that’s very consistent with human social memory.”

Dolphins live about 20 years in the wild, but as long as 45 years in captivity. In one of Bruck’s tests, a female dolphin in Brookfield Zoo named Allie responded in recognition to a call from Bailey, a female living in Bermuda. The two had lived together in the Florida Keys 20 years ago.

This would be a nearly impossible study to do with dolphins in the wild, but this research does suggest that dolphins have a much more detailed memory than previously thought. It’s always fascinating to see how we’re not as different from other species as we might think.

Image CC licensed by Greyloch

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