If you were to go out on the street and ask the first ten people you see whether or not they believe that dolphins are intelligent creatures, 8 out of 10 would probably say yes. If you ask two scientists the exact same question, you may be opening a discussion that could last for hours.
Most scientists to date have refused to take a firm position on the intelligence level of dolphins, and while many will concede that dolphins appear to be intelligent creatures, it is not a proven fact. The biggest problem facing researchers seems to be the actual definition of intelligence.
Darwin’s theory bases intelligence on a species’ ability to recognize what it needs to survive, while other schools of thought believe that brain size and architecture, the ability to communicate, or the ability to show joy are the indicators.
Another reason that research on dolphin intelligence is limited is that it is difficult and expensive to conduct in the wild. Captive dolphins may respond differently depending on their environment and therefore may not be representative of the wild dolphin. While the US Navy has conducted extensive research on the dolphins and has even trained them to search for and even tag mines, that information has not been made public.
While most of us outside of science know that dolphins communicate with each other and are some of the most playful animals in the universe, we have never been exposed to the intricacies of the dolphin brain. Consequently, you may be surprised to learn that the dolphin brain is actually much larger than the human brain. Dolphins have two hemispheres like humans, however theirs are divided into four lobes instead of three. The fourth lobe in the dolphin brain actually houses all the senses, whereas in a human, the senses are divided. Some believe that having all the senses in one lobe allows the dolphin to make immediate and often complicated judgments that are beyond the reach of human ability.
By studying the neocortex, which is the outer surface of the brain responsible for forming perceptions, memories, and thoughts, dolphins have more gyrus than the most intelligent humans. Dolphins are also thought to be able to use their separate brain hemispheres as they have separate blood supplies, something unique to the dolphin. To add further weight to this assumption, dolphins can also move their eyes independently, which has led some researchers to suggest that the dolphin can actually sleep with one side of its brain at a time.
Some researchers have suggested that the size and complexity of the brain at birth is a better measure of intelligence. However, if that investigation holds up, once again the dolphin emerges victorious. The bottlenose dolphin has a brain mass at birth that is 42.5% of the brain mass of an adult human. Humans at birth have 25% of their adult counterparts. At 18 months, the bottlenose dolphin’s brain mass is 80% of that of an adult human, which does not usually reach this level until three or four years of age.
While the research that has been obtained certainly makes it seem as though the dolphin may be the closest to our own level of intelligence, it may be quite some time before it is actually proven. Until then, his true capabilities will remain a mystery.