1 00:00:07,176 --> 00:00:12,117 In 1985, three researchers on a dolphin-studying expedition 2 00:00:12,117 --> 00:00:13,662 got a little bored. 3 00:00:13,662 --> 00:00:16,913 To lighten things up, one pretended to be Poseidon 4 00:00:16,913 --> 00:00:21,565 by placing a seaweed garland on his head and then throwing it into the ocean. 5 00:00:21,565 --> 00:00:27,193 Moments later, a dolphin surfaced with the seaweed crowning her head. 6 00:00:27,193 --> 00:00:29,274 Sure, this could have been a coincidence, 7 00:00:29,274 --> 00:00:35,255 but it's also entirely possible that the dolphin was mimicking the scientist. 8 00:00:35,255 --> 00:00:39,940 That's because dolphins are one of the smartest animals species on Earth. 9 00:00:39,940 --> 00:00:42,990 So exactly how smart are they? 10 00:00:42,990 --> 00:00:45,108 Like whales and porpoises, 11 00:00:45,108 --> 00:00:47,709 dolphins belong to the group of aquatic mammals 12 00:00:47,709 --> 00:00:52,540 known as cetaceans who comprise 86 different species, 13 00:00:52,540 --> 00:00:57,104 and share a common link with ungulates, or hoofed animals. 14 00:00:57,104 --> 00:00:59,500 Originally land mammals, 15 00:00:59,500 --> 00:01:04,160 the first cetaceans entered the water about 55 million years ago 16 00:01:04,198 --> 00:01:06,791 as large predators with sharp teeth. 17 00:01:06,791 --> 00:01:11,550 Then, a shift in ocean temperatures about 35 million years ago 18 00:01:11,550 --> 00:01:14,568 reduced the availability of prey. 19 00:01:14,568 --> 00:01:17,686 One group of cetaceans who survived this distruption, 20 00:01:17,686 --> 00:01:22,103 the odontocetes, wound up smaller with less sharp teeth, 21 00:01:22,103 --> 00:01:25,538 but also larger and more complex brains 22 00:01:25,538 --> 00:01:28,238 that allowed for complex social relationships, 23 00:01:28,238 --> 00:01:31,893 as well as echolocation to navigate and communicate. 24 00:01:31,893 --> 00:01:33,466 Jump ahead to the present, 25 00:01:33,466 --> 00:01:38,227 and modern dolphins' brains are so large that their encephalization quotient, 26 00:01:38,227 --> 00:01:41,566 their brain size compared to the average for their body size, 27 00:01:41,566 --> 00:01:43,855 is second only to humans. 28 00:01:43,855 --> 00:01:46,603 Dolphins have evolved to survive 29 00:01:46,603 --> 00:01:49,844 through their ability to form complex social networks 30 00:01:49,844 --> 00:01:54,021 that hunt, ward off rivals, and raise offspring together. 31 00:01:54,021 --> 00:01:56,728 For example, one group of Florida dolphins 32 00:01:56,728 --> 00:02:01,023 practices a sophisticated form of cooperation to hunt fish. 33 00:02:01,023 --> 00:02:04,785 A dolphin designated as "the net-maker" kicks up mud 34 00:02:04,785 --> 00:02:06,647 while another gives the signal 35 00:02:06,647 --> 00:02:12,075 for the other dolphins to simultaneously line up and catch the escaping fish. 36 00:02:12,075 --> 00:02:16,223 Achieving a goal like this requires deliberate planning and cooperation, 37 00:02:16,223 --> 00:02:20,521 which, in turn, requires some form of intentional communication. 38 00:02:20,521 --> 00:02:24,025 Dolphins pass down their communication methods and other skills 39 00:02:24,025 --> 00:02:26,046 from generation to generation. 40 00:02:26,046 --> 00:02:30,157 Different dolphin populations exhibit variations in greetings, 41 00:02:30,157 --> 00:02:33,237 hunting strategies, and other behaviors. 42 00:02:33,237 --> 00:02:37,510 This sort of cultural transmission even extends to tool use. 43 00:02:37,510 --> 00:02:41,303 One group of bottlenose dolphins off the Australian coast 44 00:02:41,303 --> 00:02:43,514 nicknamed The Dolphin Sponge Club, 45 00:02:43,514 --> 00:02:49,073 has learned how to cover their rostrums with sponges when rooting in sharp corals, 46 00:02:49,073 --> 00:02:51,859 passing the knowledge from mother to daughter. 47 00:02:51,859 --> 00:02:54,954 Dolphins have even demonstrated language comprehension. 48 00:02:54,954 --> 00:02:58,068 When taught a language based on whistles and hand gestures, 49 00:02:58,068 --> 00:03:00,544 they not only understood what the signals meant, 50 00:03:00,544 --> 00:03:02,849 but that their order had meaning: 51 00:03:02,849 --> 00:03:05,353 the difference between bringing the ball to the hoop 52 00:03:05,353 --> 00:03:07,633 and bringing the hoop to the ball. 53 00:03:07,633 --> 00:03:11,974 So they were able to process two of the main elements of human language: 54 00:03:11,974 --> 00:03:14,571 symbols that stand for objects and actions, 55 00:03:14,571 --> 00:03:18,556 and syntax that governs how they are structured. 56 00:03:18,556 --> 00:03:22,772 Dolphins are also one of the few species who pass the mirror test. 57 00:03:22,772 --> 00:03:27,719 By recognizing themselves in mirrors, they indicate physical self-awareness, 58 00:03:27,719 --> 00:03:31,786 and research shows they can recognize not just their bodies, 59 00:03:31,786 --> 00:03:36,956 but also their own thoughts, a property called metacognition. 60 00:03:36,956 --> 00:03:39,653 In one study, dolphins comparing two sounds 61 00:03:39,653 --> 00:03:44,371 could indicate a same, different, or uncertain response. 62 00:03:44,371 --> 00:03:45,625 Just like humans, 63 00:03:45,625 --> 00:03:49,384 they indicated uncertainty more often with difficult trials, 64 00:03:49,384 --> 00:03:51,572 suggesting they're aware of what they know, 65 00:03:51,572 --> 00:03:54,557 and how confident they feel about that knowledge. 66 00:03:54,557 --> 00:03:57,443 But some of the most amazing things about dolphins 67 00:03:57,443 --> 00:04:01,172 are their senses of empathy, altruism, and attachment. 68 00:04:01,172 --> 00:04:05,982 The habit of helping injured individuals extends across the species barrier 69 00:04:05,982 --> 00:04:07,817 as evidenced by the many accounts 70 00:04:07,817 --> 00:04:11,476 of dolphins carrying humans to the surface to breathe. 71 00:04:11,476 --> 00:04:14,142 And like us, dolphins mourn their dead. 72 00:04:14,142 --> 00:04:16,353 When we consider all the evidence, 73 00:04:16,353 --> 00:04:19,669 we may wonder why humans still hunt dolphins for meat, 74 00:04:19,669 --> 00:04:22,176 endanger them through fishing and pollution, 75 00:04:22,176 --> 00:04:25,028 or imprison them to perform tricks. 76 00:04:25,028 --> 00:04:28,534 The ultimate question may not be whether dolphins are intelligent 77 00:04:28,534 --> 00:04:30,424 and complex beings, 78 00:04:30,424 --> 00:04:34,601 but whether humans can empathize with them enough to keep them safe and free.