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  • In 1985, three researchers on a dolphin-studying expedition

  • got a little bored.

  • To lighten things up, one pretended to be Poseidon

  • by placing a seaweed garland on his head and then throwing it into the ocean.

  • Moments later, a dolphin surfaced with the seaweed crowning her head.

  • Sure, this could have been a coincidence,

  • but it's also entirely possible that the dolphin was mimicking the scientist.

  • That's because dolphins are one of the smartest animals species on Earth.

  • So exactly how smart are they?

  • Like whales and porpoises,

  • dolphins belong to the group of aquatic mammals

  • known as cetaceans who comprise 86 different species,

  • and share a common link with ungulates, or hoofed animals.

  • Originally land mammals,

  • the first cetaceans entered the water about 55 million years ago

  • as large predators with sharp teeth.

  • Then, a shift in ocean temperatures about 35 million years ago

  • reduced the availability of prey.

  • One group of cetaceans who survived this disruption,

  • the odontocetes, wound up smaller with less sharp teeth,

  • but also larger and more complex brains

  • that allowed for complex social relationships,

  • as well as echolocation to navigate and communicate.

  • Jump ahead to the present,

  • and modern dolphins' brains are so large that their encephalization quotient,

  • their brain size compared to the average for their body size,

  • is second only to humans.

  • Dolphins have evolved to survive

  • through their ability to form complex social networks

  • that hunt, ward off rivals, and raise offspring together.

  • For example, one group of Florida dolphins

  • practices a sophisticated form of cooperation to hunt fish.

  • A dolphin designated as "the net-maker" kicks up mud

  • while another gives the signal

  • for the other dolphins to simultaneously line up and catch the escaping fish.

  • Achieving a goal like this requires deliberate planning and cooperation,

  • which, in turn, requires some form of intentional communication.

  • Dolphins pass down their communication methods and other skills

  • from generation to generation.

  • Different dolphin populations exhibit variations in greetings,

  • hunting strategies, and other behaviors.

  • This sort of cultural transmission even extends to tool use.

  • One group of bottlenose dolphins off the Australian coast

  • nicknamed The Dolphin Sponge Club,

  • has learned how to cover their rostrums with sponges when rooting in sharp corals,

  • passing the knowledge from mother to daughter.

  • Dolphins have even demonstrated language comprehension.

  • When taught a language based on whistles and hand gestures,

  • they not only understood what the signals meant,

  • but that their order had meaning:

  • the difference between bringing the ball to the hoop

  • and bringing the hoop to the ball.

  • So they were able to process two of the main elements of human language:

  • symbols that stand for objects and actions,

  • and syntax that governs how they are structured.

  • Dolphins are also one of the few species who pass the mirror test.

  • By recognizing themselves in mirrors, they indicate physical self-awareness,

  • and research shows they can recognize not just their bodies,

  • but also their own thoughts, a property called metacognition.

  • In one study, dolphins comparing two sounds

  • could indicate a same, different, or uncertain response.

  • Just like humans,

  • they indicated uncertainty more often with difficult trials,

  • suggesting they're aware of what they know,

  • and how confident they feel about that knowledge.

  • But some of the most amazing things about dolphins

  • are their senses of empathy, altruism, and attachment.

  • The habit of helping injured individuals extends across the species barrier,

  • as evidenced by the many accounts

  • of dolphins carrying humans to the surface to breathe.

  • And like us, dolphins mourn their dead.

  • When we consider all the evidence,

  • we may wonder why humans still hunt dolphins for meat,

  • endanger them through fishing and pollution,

  • or imprison them to perform tricks.

  • The ultimate question may not be whether dolphins are intelligent

  • and complex beings,

  • but whether humans can empathize with them enough to keep them safe and free.

In 1985, three researchers on a dolphin-studying expedition

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B1 TED-Ed dolphin complex hunt sharp hoop

【TED-Ed】How smart are dolphins? - Lori Marino

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    SylviaQQ posted on 2015/09/06
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