Which animal has the strongest memory performance?

The best memory in the animal kingdom

If someone has an exceptionally good memory, then one likes to try the elephant in animal comparison. Perhaps, according to the latest scientific findings, it should be better said: This person has a memory like a bottlenose dolphin.

As the US biologist Jason Bruck found out, this subgroup of dolphins, which also belonged to "Flipper", can remember the "signature whistle" of conspecifics for more than 20 years - even if they haven't seen or heard them for just as long to have. This is unprecedented in the animal kingdom and also puts elephants in the shade.

Smart naming

But this "signature whistle" itself, which marine biologists Vincent Janik and Stephanie King have been researching for years, is astonishing. It was known that the clever marine mammals develop their own name call in childhood and whistle the individual tone sequence in front of them - similar to a child who learns his name and says it to anyone who asks for it.

The two scientists from the Scottish University of St. Andrews, one of the world's leading centers for research into intelligence in animals, wanted to find out whether and how these "names" were still used later. To this end, King and Janik followed groups of bottlenose dolphins off the Scottish coast for several years, recorded their calls and analyzed them.

After a while they played different signatures to the animals. The result of their experiment, which the two biologists published in the journal "PNAS": The animals did not react to the names of other bottlenose dolphins, regardless of whether they were strange or familiar. However, when the animals played a copy of their own signature, they responded immediately.

The two researchers also report that groups of bottlenose dolphins that are unknown to one another and meet on the high seas would intensively exchange these signatures - similar to a group of people who introduce themselves to one another. Above all, bottlenose dolphins can also address each other specifically by name. They would therefore be the first mammals besides humans with this ability.

The purpose of this ability is obvious to Janik and King: The use of the name is the basis for groups of bottlenose dolphins to stick together. And that in turn is the prerequisite for developing complex social systems.

As Janik and King also noted, the name apparently does not lose its meaning for an entire long life of bottlenose dolphins (the animals can live up to 50 years in captivity). And this fact in turn forms the basis of the new study by the US marine biologist Jason Bruck from the University of Chicago, who wanted to find out how long the bottlenose dolphins remember the whistled names of their conspecifics.

To do this, the researcher examined a total of 53 different bottlenose dolphins that lived in six different zoos and dolphinariums in the USA and Bermuda. Previously, most of the animals had spent months or years in one of the other six facilities with other animals.

For his work in the Royal Society's "Proceedings B" magazine, Bruck did something very similar to his Scottish colleagues: he played strange and familiar signature whistles to the dolphins and observed how the animals reacted. At first there were unknown whistles until the animals began to get bored. Exactly then he played the whistle of a former companion - and the dolphins actually listened visibly: They swam towards the loudspeaker, circled it and whistled at it - as if they wanted to elicit further whistles from it.

Recognition in the test

This recognition also took place after an extremely long time: A female dolphin named Allie recognized the female Bailey, with whom it had lived as a young animal, although the two had not seen each other for more than 20 years. Gender and relationship did not affect memory.

For Bruck, however, it is not entirely clear why the dolphins need their good memories. It may be used for group formation on the high seas - or it may simply be a by-product of their intelligence. (Klaus Taschwer, DER STANDARD, August 7th, 2013)