How smart are dolphins? Very smart. Actually, answering this question is not that simple, mainly due to the fact that one must first answer the question: How do you define intelligence?
Well, it depends on who you ask. Darwin, responsible for the much accepted theory of evolution, created a cosmic hierarchy of intelligence based on how efficient a species became at doing the thing they need to survive. Others will cite communication as the mark of intelligence. Sterling Bunnell, MD, a psychiatrist and ecologist, cites extreme playfulness and humor as a hallmark of intelligence. Many people leap to the source and analyze the brain-its size and architecture.
Let's look at how dolphins rate using each of these definitions.
Dolphins, as well as all cetaceans (whales and porpoises) have big brains. Their brains are larger that humans; in fact, they have the largest brains on earth. But size doesn't mean everything. The architecture of this organ-which thinks, schemes, plans, and projects-is considered to be more important than size. The human brain has two hemispheres each of which is divided into three concentric lobar formations from the innermost core: the rhino lobe, followed by the limbic lobe and finally the supralimbic lobe.
The dolphin brain also has two hemispheres, but in addition to the three lobes, it has a fourth well-developed lobe named the paralimbic lobe. This lobe, which is unique to cetaceans, is the lobe where all senses (hearing, touch, taste, vision, and motor activities) are located. The benefit of having all the senses and motor activities in one lobe (as opposed to their being separate, as they are in humans) is that it provides the ability to make immediate and complex perceptions far beyond human conception.
On the surface of the brain is a cellular covering called the neo-cortex. It is the most recently developed part of the brain and is responsible for forming perceptions, memories and thoughts, and what we consider to be higher intellect. All the folds and convolutions of the neo-cortex, which make the brain resemble a cauliflower, create more surface area of the cortex in a smaller space. Dolphins have more convolution than even healthy, intelligent humans.
There possibly might be another difference in the dolphin brain-they might use the two hemispheres completely separately. The halves do have separate blood supplies, a trait exclusive to these mammals. They also have independent eye movement, which led many to believe that dolphins sleep by shutting down on half of their brains at a time!
Onto the lighter side: humor and playfulness. If these were indeed the mark of intelligence, dolphins would be at the top of the cosmic ladder. Humor and play are high on the evolutionary scale; only those who have finished their survival duties have time to play. And there has been evidence taken from cases of brain damage in humans that indicates a high ratio of neo-cortical association neurons to limbic system to brain stem neurons is necessary for humor and higher forms of creativity. Dolphins have a higher neo-cortical-limbic ratio than even healthy, intelligent humans. Dolphins are full of practical jokes and have been seen plucking a bird's tail feathers from behind, pulling fish by the tail and tossing manta rays in their mouths like Frisbees. Dolphins are also extremely sensual mammals, caressing each other constantly. They are also one of the only other species to have intercourse when the female is not in estrus; in other words, simply because it feels good. Dolphins also participate in an act called genital-beak perpulsion, which resembles what we call oral sex.
One cannot analyze dolphin intelligence without mentioning communication. The question really seems to be: Can they talk? Dolphins communicate with each other, no doubt. The fact that they live in water makes their communication very alien to us. Sound moves faster and further in water. The dolphins have behavior related to their unique communication, which is unexplainable to us. For instance a behavior I call "performing surgery." I coined this term on a dolphin expedition during which I observed many members of a pod echolocating toward one individual dolphin. The purpose of this behavior remains a mystery, perhaps because their communication does not resemble ours. Can we talk to them? Dolphins do respond to human emotion-as if emotion travels in water on waves as was thought by the ancient Greeks-by saving humans in peril.
So are dolphins smart? It depends which criteria you look at. Most writers never want to answer this, possibly because there is such difficulty in gauging intelligence even within our own species, or perhaps simply because intelligence is so very nebulous. And what if dolphins were as smart as we all suspect them to be? What would it mean? Have we found another species with whom we can communicate? I attempted to answer this question from a philosophical and theoretical point of view, shying away from the mystical aspect of dolphins-which is why we seem to wonder about them in the first place.