Dr. Ken Marten at Sea Life Park in Hawai’i recently demonstrated that dolphins recognize themselves in mirrors, which shows dolphins are self-aware, a trait shared with only humans and great apes. Dolphins were also taught to recognize some 40 spoken Hawaiian words by Dr. Wayne Batteau, and were taught to imitate English by Dr. John C. Lilly, M.D. Dolphins currently working with Dr. Louis Herman in Hawai’i can recognize some 300 hand signs in some 2000 combinations.2 Dolphins have done better at language tasks than any other creature. Research in Russia by Markov and Ostrovskaya concludes that dolphins have their own language with up to a trillion “words” possible.3
Dolphins, along with other Cetacea (dolphins and whales), have acute senses, which are faster and have a broader bandwidth than our senses. They have large brains, like the Sperm whale with the largest brain - 9600 grams vs. our 1400 grams. The Cetacean brain is comparable to ours in complexity and processing capability. With larger brains, they have more processing capacity – just as a large computer has greater capability than a small one. The Cetacean brain has expanded most in the cerebral cortex, where thinking, reasoning, and other “higher” processes are felt to occur.
The brain of a dolphin, for example, is larger than the human’s (at a weight of some 1700 grams) and has about 40% more association cortex (where we feel thinking occurs) than a human. In addition, humans use a large part of their available processing capacity just to deal with gravity and balance. The Cetacea live in a buoyant environment where gravity is much less a factor. This leaves large amounts of their brains free for other tasks. So the Cetacea have greater available brain capacity than humans.
I conclude that the Cetacea (dolphins and whales) are self-aware, fully conscious, sentient, and have their own complex language. Because they have larger brains, more available cortex, and more processing power available (because of their lives in water) the Cetacea, including the dolphins, are more intelligent than we are. The Sperm whale has the largest brain (much of it association cortex) and likely has proportionately greater processing capacity - making it in all probability - the most intelligent creature on Earth.