Nice to hear you! Dolphins recognise old friends even after 20 years apart
New study shows that the mammals have the longest social memory of any non-human species
Dolphins are able to remember one another's signature calls for at least 20 years making it the longest memory for "faces" among animals - perhaps even surpassing the ability of people to remember one another from their appearances alone.
Every dolphin has a unique whistle which is used as a signature call and stays with them unchanged throughout life. These identifying noises are even more reliable than the facial features used by people to recognise each other, which notoriously change over time.
Now a study has shown that when dolphins have been separated for 20 years or more they are still able to distinguish the whistle call of a former close companion from a host of other calls emitted by complete strangers, scientists said.
This kind of "social memory" surpasses the recognition abilities of elephants, primates and all other intelligent animals that have been studied in this way, said Jason Bruck, who carried out the work whilst studying for is PhD at the University of Chicago.
"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," Dr Bruck said.
"This shows us an animal operating cognitively at a level that's very consistent with human social memory. This is the kind of study you can only do with captive groups where you know how long the animals have been apart. To do a similar study in the wild could be almost impossible," he said.
The study, published in the journal Proceedings of the Royal Society of London B, involved collecting the recorded signature whistles of 53 different bottlenose dolphins living at six different facilities, from the Brookfield Zoo near Chicago to Dolphin Quest in Bermuda.
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