To most observers, the essence of intelligence is cleverness, a versatility in solving novel problems. Bertrand Russell once wryly noted: Animals studied by Americans rush about frantically, with an incredible display of hustle and pep, and at last achieve the desired result by chance. Animals observed by Germans sit still and think, and at last evolve the solution out of their inner consciousness. Besides commenting on the scientific fashions of 1927, Russells remark illustrates the false dichotomy usually made between random trial and error (which intuitively seems unrelated to intelligent behavior) and insight. It takes an interplay between both.
Foresight is also said to be an essential aspect of intelligence--particularly after an encounter with one of those terminally clever people who are all tactics and no strategy. Psychologist Jean Piaget emphasized that intelligence was the sophisticated groping that we use when not knowing what to do. Personally, I like the way neurobiologist Horace Barlow of the University of Cambridge frames the issue. He says intelligence is all about making a guess that discovers some new underlying order. This idea neatly covers a lot of ground: finding the solution to a problem or the logic of an argument, happening on an appropriate analogy, creating a pleasing harmony or a witty reply, or guessing what is likely to happen next. Indeed, we all routinely predict what comes next, even when passively listening to a narrative or a melody. That is why a jokes punch line or a musical parody brings you up short--you were subconsciously predicting something else and are surprised by the mismatch.
Both intelligence and consciousness concern the high end of our mental life, but they are frequently confused with more elementary mental processes, such as ones we would use to recognize a friend or tie a shoelace. Of course, such simple neural mechanisms are probably the foundations from which our abilities to handle logic and metaphor evolved.
But how did that occur? Thats an evolutionary question and a neurophysiological one as well. Both kinds of answers are needed if we are to understand our own intelligence. They might even help us appreciate how an artificial or an exotic intelligence could evolve.
Did our intelligence arise from having more of what other animals have? The two-millimeter-thick cerebral cortex is the part of the brain most involved with making novel associations. Ours is extensively wrinkled, but were it attened, it would occupy four sheets of typing paper. A chimpanzees cortex would fit on one sheet, a monkeys on a postcard, a rats on a stamp.
Yet a purely quantitative explanation seems incomplete. I will argue that our intelligence arose primarily through the refinement of some brain specialization, such as that for language. The specialization would allow a quantum leap in cleverness and foresight during the evolution of humans from apes--perhaps the creative explosion seen about 50,000 years ago, when people who had looked like us since 200,000 years ago finally began acting like us. If, as I suspect, that specialization involves a core facility common to language, the planning of hand movements, music and dance, it has even greater explanatory power.
A particularly intelligent person often seems quick and capable of juggling many ideas at once. Indeed, the two strongest inuences on your IQ score are how many novel questions you can answer in a fixed length of time and how good you are at manipulating half a dozen mental images--as in those analogy questions: A is to B as C is to (D, E or F).
VERSATILITY is another characteristic of intelligence. Most animals are narrow specialists, especially in matters of diet: the mountain gorilla consumes 50 pounds of green leaves each and every day. In comparison, a chimpanzee switches around a lot--it will eat fruit, termites, leaves, and even a small monkey or piglet if it is lucky enough to catch one. Omnivores have more basic moves in their general behavior because their ancestors had to switch between many different food sources. They need more sensory templates, too--mental images of things such as foods and predators for which they are on the lookout. Their behavior emerges through the matching of these sensory templates to responsive movements.