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Background/ Brains and cognition - part 2

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Behavioral and experimental evidence for dolphin intelligence

I see you!Besides the clues found in the size and structure of the dolphin brain, there is also a large body of research data available, both experimental and observational, that is indicative of dolphins being among the most intelligent species on this planet.  Numerous experiments on dolphin cognition have demonstrated that they are capable of understanding symbolic representations of objects and events (see previous dolphin language research), of understanding various abstract rules, pointing gestures and gazes by humans, self recognition in mirrors and on video recordings, and awareness of their own behaviors and knowledge states (also known as metacognition), shown in one study by indicating their own certainty or uncertainty about which of two sounds was higher pitched.

Cooperative baitball feedingOne of the strongest signs of social intelligence is the ability to imitate others.  Dolphins are very good at vocal mimicry – making them the only mammal besides humans capable of doing so.  In one study this was demonstrated by playing a variety of frequency modulated sounds to a dolphin named Phoenix, which she was able to mimic accurately, sometimes even at an octave higher or lower than the model sound (a skill which has not yet been shown in e.g. songbirds).  Dolphins are also excellent behavioral imitators: they have been shown capable of mimicing a variety of behaviors, both familiar and new, from either humans, other dolphins or their own previous behaviors.

In the wild, dolphins form very strong social bonds that usually last a lifetime.  They cooperate and help each other in activities such as feeding, e.g. herding fish in prey balls or beaching them, as well as even more specialized foraging techniques that are only found in certain populations and that seem to be transmitted culturally from generation to generation.  They have also been reported to use tools, such as picking up sponges to protect their rostrums from poisonous fish and stingrays during bottom feeding.

Finally, dolphins are among the only wild animals that seem to voluntarily seek and enjoy contact with humans, such as bow-riding boats or allowing humans to swim with them.  There are also some coastal villages in Africa, Brazil, and Myanmar where dolphins have been cooperating with the local fishermen by herding fish into the nets, after which the catch is shared.  What’s more, there have been various cases reported quite recently (e.g. in California and New Zealand) where dolphins seemed to protect human swimmers from shark attacks.  This is very remarkable behavior, and protecting members of another species at risk of one’s own life can be thought of as the ultimate form of altruism.  And this altruistic behavior is not only limited to humans:  in 2008 a dolphin apparently led two stranded pigmy whales back to safety.

NEXT: Previous dolphin language research