When you look a dolphin in the eyes, they seem almost human-like, and when they smile, you feel like someone you know is smiling at you. What makes dolphin trainers, zoo keepers, and researchers psychologically bond to these animals? What makes dolphins so different from other animals?
In The Hitchhiker's Guide to the Galaxy, dolphins are the second most intelligent creatures on Earth (after mice, and followed by humans), who tried in vain to warn humans of the impending destruction of planet Earth. Their behavior was misconstrued as entertainment and playful acrobatics, and in the end they departed from Earth, leaving the message "so long and thanks for all the fish". The intelligence of dolphins is also debated in many other literary works, by Larry Niven, Karen Hesse, Ken Grimwood, Anne McCaffrey, and many others. If you ask ten random people whether or not they think dolphins are intelligent, 80% would most likely say yes, but if you were to ask two researchers, the debate could last for hours; why?
Charles Darwin believed that intelligence is based on the ability of a species to recognize what exactly it needs to survive; other schools of thought believed that the size of the brain is what mattered, along with the ability to communicate, and the ability to exhibit playfulness.
Conclusions about the nature and magnitude of dolphin intelligence are far from being reached, most likely due to difficulties and limitations in this sort of study; it is difficult and expensive to do this sort of research in the wild, and dolphins kept in captivity may respond differently and falsely represent wild dolphins.
Most of the people outside the scientific realm are confident that dolphins are one of the most intelligent animals there are, and they have a right to believe so. The dolphin brain is much larger than the human brain in size. For example, tursiops truncates, or the Bottlenose dolphin, has a brain mass of 1500-1700 grams, which, compared to the average mass of a human brain (1300-1400 grams), is much larger. The chimpanzee, which is also an animal believed to be very intelligent, has the brain mass of 400 grams. At birth, Bottlenose dolphins have a brain mass 42.5% that of an adult dolphin (while newborn humans have 25% the mass of adults), and the Bottlenose dolphins achieve 80% by eighteen months. Human beings do not achieve this by the age of three or four years.
Dolphins' cerebral cortex is 40% larger than a human's, with wrinkles of equal complexity, along with a similarly developed frontal lobe. Dolphin brain stem transmission time is much faster than normally found in humans, and is about the same as found in rats. Scientists speculate that the faster brain stem transmission time, as well as the paralimbic lobe, helps make processing of sound much speedier. A dolphin's neural area used for visual imaging is only about 1/10 of that of a human brain, while the area devoted to acoustic imaging is about 10 times the area in the human brain.
It may take a few more years to understand this amazing animal, though the research that has been obtained makes it seem as though the dolphin is closest to our level of intelligence (whatever it may be), but until then, their true capabilities will remain a mystery.