Many people, including scientists, assume that bigger brains are possessed by species that are more intelligent. This is a convenient assumption, since we Homo sapiens have the biggest brains of any species currently on earth. But there are less egocentric reasons to accept this view as well.
First, it is possible to look at the skulls of species that preceded us millions of years ago, and to measure the size of the brain that fit inside it. As brain volumes increased, so has evidence of increased intelligence. Stone tools became more sophisticated, patterns of hunting and trade more complex, and artifacts like jewellry, tokens, and manifestations of art, music, and religion eventually appear.
There is also the same relationship between brain size and intelligence among animals living on earth today. Or at least that’s what we thought. But there are some exceptions that are beginning to cast doubt on an unequivocal Bigger is Brighter stance.
Among humans, for instance, women on the average have smaller brains than men. Until women gained the vote in Britain and the United States in the early 20th century, men confidently used the smaller physical size of female brains as evidence that they were not smart enough to be trusted with a vote. Every test of intelligence that we have devised in the modern world, however, shows that while female intelligence may differ on the average from male intelligence, it is not inferior. Women tend be better at languages and at intuiting other’s thoughts, intentions, or feelings. Men tend to be better at mathematical and spatial abilities. These are only average differences, though, and so many women are brilliant mathematicians, and many men are brilliant linguists and poets.
There is also evidence that the brain of Neanderthal man, which belonged to the Homo genus but not the sapiens species, had brains that were larger than those of their contemporary Homo sapiens. But although Neanderthal man spread throughout Europe and lived side-by-side with Homo sapiens for thousands of years, he has been extinct for at least fifteen thousand years. Possibly for ten thousands years more than that.
Another problem is the difficulty of equating intelligence among different kinds of animals. Bees can navigate far from home; birds can navigate practically around the world. Mankind didn’t figure out how to do it until three hundred years ago. The more we study other species, the more we realize they can figure out. How do we compare what they can do with problems that we can solve? or with those we can’t?
Finally, perhaps the most disquieting of all for those quietly confident that an IQ score over 125 puts them into an elite category is the research finding that high scores on intelligent tests do not predict how successful one is going to be in amassing money. In fact, people with high IQ’s often have more financial difficulties than people who are slightly above-average.