There are many times that dolphins have rescued swimmers or fought off attacking sharks at real risk to themselves. Because of these actions, humans tend to feel there is a special bond between dolphins and themselves and that this bond is based on mutual intelligence or a wished for understanding.
From as early as the 17th century scientists have been impressed by the size of dolphin brains and rated them near the top of the ‘non-human’ intelligence list. Many cetaceans (whales) do have large brains and, relative to body size, toothed whales have larger brains than baleen whales. In fact, the relative brain size of bottle nose dolphins is nearly the same as that of humans. Dolphin brains range from about 0.25% to 1.5% of their body weight and human brains are about 1.9% of our body weight.
Another measure of brain development is based on the number of folds in the grey matter (cerebral cortex). This is the part of the brain that gives us conscious control of our bodies and thoughts. Toothed whale brains have more folding than baleen whales but much of this is taken up for sound production and processing. Toothed whale brains, like the dolphin’s, have folding that resembles that of hoofed animals like horses and deer.
We don’t know if dolphins have a language but we do know that they share information about their surroundings, their emotions, and their identity through acoustic whistles and clicks.
Memory experiments with dolphins showed that their picture of the world and their ability to remember it was better when based on their sonar and not so good when based on sight. Their memory was best when they could use sonar and sight together.
Dolphins have also been taught ‘words’(using hand signals) that can be put together in two-word sentences like “get ball”. Scientists found that they understood these sentences about 80% of the time. Able to grasp the basics of human language, it may be possible to communicate in two and three word format with dolphins in the future. If we do decide to talk with dolphins it will be best to choose our subjects wisely since research shows a large variation in ‘intelligence’ among species.
We think of intelligence as the ability to understand our surroundings and process information so that we can react in the most favorable way. In this way intelligence is not the same as instinct where reactions are ‘pre-programmed’ in the brain. In the animal kingdom, species with higher intelligence tend to be social animals that live in groups.
It is thought that the evolution of intelligence is related to the need to understand group dynamics and the individual’s place within them. The ‘smarter’ dolphins operate in social structures similar to dogs and primates.
Having a well developed brain and intellect; humans are always quick to make lists showing the relative intelligence of other animals with us at the top. To be fair, we must always ask the question: “How intelligent would we be in the dolphin’s world of sound and social behavior; in a world without landmarks and signs; and without shelter and an organized food supply?”