Dolphin's Cognitive Abilities

 Dolphins are my favorite animals, partly because of their extra-cute appearances: “friendly smile”, little flippers, and sleek and shiny body. But their intelligence is what amazes me the most. I once watched a video about dolphin training. I remember in one of the training sessions, the trainer asks the dolphin to go grab a ball from a basket, yet there is no ball in that basket. So the dolphin takes back the empty basket with him to show the trainer and presses the “No” button available. In another session, the trainer gestures two dolphins to perform two simple tricks then gestures them to perform the two tricks in one action. The dolphins immediately perform a combination of the two tricks without the trainer teaching them how. These are all very creative  that  most other species, including many primates, cannot come up with. This makes me want to explore more about their cognitive abilities.

We all know that dolphins have very large brains. In fact, their brain is 25% heavier than human brain. The average weight of dolphin brain is about 1.7kg, while the average weight of human brain is 1.3kg. Does this mean that dolphins are smarter than humans? Not necessarily. There is another important factor that determines an animal’s intelligence: encephalization quotient (EQ). This is value gained by comparing brain size with whole body size. It is considered that the larger the EQ, the higher the intelligence. Humans, of course, have the largest EQ, which about 7, in the animal world. Most other animals’ EQ are seven times lower than humans. Those with an EQ larger than 1 have larger than expected brain size while an EQ smaller than 1 means a smaller than expected size. Dolphin has the second largest EQ, about 4 or 5, which is just below humans. If the theory about brain size and intelligence is correct, then this could explain why dolphins show high level of intelligence and cognitive abilities. In this sense, the dolphins resemble the humans even more than other primates. One other interesting fact is that Cetaceans(the order that contains whales, dolphins and porpoises) have lateralized and asymmetrical brain functions like the mammals even though they have completely different evolutionary process.

Brain structure and size are important factors that affect intelligence. But the more important things are the behaviors of dolphins. Like I mentioned earlier, their high level of intelligence and cognition help them perform many very advanced and clever tricks that we watch in aquariums (I though I am completely against captivity).

One important aspect of dolphin cognition is their communication and vocalization. The dolphins use 3 types of vocal signal collection: “broad-band, short-duration clicks”(1) used for orientation and perception, “wide-band pulsed”(1) sound used during socialization and “narrow band frequency-modulated whistles”(1), which are also used for socialization. The dolphins have also have “names” for each other. Individual dolphin uses a unique whistle to identify himself, especially when he is in dangerous situations like being separated from his group. An earlier misconception about dolphin vocalization is that dolphin’s whistles are mainly self-identifications. Later scientists noticed that dolphins use a lot more complicated whistles during complex social situations. This suggests that the dolphins are exchanging very complex information other than simply self-identification. Maybe the dolphins actually have a complex language like humans do. (And maybe they are trying to come up a plan to dominate the world?)

Another amazing ability of dolphins is language learning. The dolphins can process both “semantic and syntactic information”(3). They perfectly understand the significance of word order that “the changes in word order changes meaning”(3) and make the correct reaction based on their correct understanding of the sentence. Besides that, the dolphins also learn dolphin “language” from each other. Just like human children learning to talk, dolphin calves also show beginning stages of whistle learning. Their language learning process is just human’s: mimicking the adults’ dolphins , memorizing, and eventually understanding. During their learning, they also uses methods like “overproduction, vocal play, and attrition”(1) to learn to whistle, which are used only by humans and a few species of birds. This vocal learning ability has only been found in humans and these marine mammals.

Studies have also shown that dolphins are self-aware of their own behaviors. When the dolphins are given a “repeat” gesture, they can always correctly perform its previous action. If a gesture given asking the dolphins to perform something different, they are also quick to move on to a new trick. This shows that dolphins are aware of their own previous behaviors and capable of switch to new actions. Another famous test of self-awareness is the mirror test. An animal will be guided to stand in front of a mirror and look at the image in the mirror. If the animal is able to recognize its own image, then it is self-aware. Among the species  on land, only humans, guerillas, chimpanzees, and orangutans are capable of recognizing one’s own image. Other species usually mistake the image in the mirror to be another animal and start attacking or cuddling the mirror. Scientists performed the mirror test on the dolphins the same way they did on the primates and human babies: they marked the dolphin with tactile materials and put it in front of a mirror. It turns out the dolphin is capable of recognizing himself and performs self-directed behaviors like humans and large primates. There is even image showing that a dolphin examining the mark on his body. I have also seen a video on YouTube of an orca keeps “checking itself out” in front of a mirror. Dolphins are self-aware animals.

Another very interesting experiment that the scientists have done with the dolphins is testing their reactions in front of a television. Most animals usually make no response toward the television because they do not see anything significant on. Some of them will respond to the television the same way they will respond to the real world. Chimpanzees can only learn to respond to television the correct way after watching humans responding to television for a long time. But the dolphins can respond to the television in a correct way almost instantly. A trainer is giving command by gestures through the television. The dolphins does what the train gestures them to do exactly the same way they would do for a real life trainer. This simply shows that they do respond to television. When the trainer throws a ball and signals the dolphin to do the same, the dolphins followed the command using a ball they find in real life without making any attempt to get the ball from the television. This shows that they are aware of what is real and what is only a television image.

I would be surprised if anyone is still not impressed by the strong cognition of dolphins after reading this. They exhibit such a level communication skills, creative thinking, and behavioral flexibility that they can almost be humans’ counterparts in the ocean. Could it be possible that dolphins are homologous to humans? Or did they simply get smarter just to adapt to a tough environment they are living in? We cannot make a judgment yet. Either way, I will be always happy to see these beautiful animals playing in the wild ocean and be grateful that we can share a special bond with these amazing creatures.

References:

(1) Trends in Cognitive Sciences: “Communicative and other cognitive characteristics of bottlenose dolphins”

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VH9-3SX0DHN-P&_user=400777&_coverDate=07%2F31%2F1997&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000018819&_version=1&_urlVersion=0&_userid=400777&md5=97eab866754cc5dbb958d7d4e46328e7

(2) Current Biology: “Dolphin Cognition”

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VRT-4DRMNRG-5&_user=400777&_coverDate=11%2F09%2F2004&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000018819&_version=1&_urlVersion=0&_userid=400777&md5=961ea6cec57708454c44e0b4acc21e39

(3) The Animals Ethics Reader: “Exploring the Cognitive World of the Bottlenosed Dolphin”

http://books.google.com/books?hl=en&lr=&id=4TwWJ8sds84C&oi=fnd&pg=PA161&dq=dolphin+intelligence&ots=oK6AdN5Umo&sig=_Ej2VWfuAU0BfGtf8lWo_W2DPR0#v=onepage&q=dolphin%20intelligence&f=false