Intelligence and brain

Studies of language learning, both in humans and in nonhuman primates such as chimpanzees, have led us to ask when and how languages evolved among early humans.

One factor on this evaluation was intelligence, for it is clear that language ability is closely linked to intelligence.

If we look at the fossil remains of our prehuman ancestors, we note that during the evolution of the first humanlike species, dating from about 3 to 4 millions years ago, into modern humans, the size of the brain more than doubled.

A major reason for this increase might have been the need for a larger memory to contain the sounds and meanings of language.

However, the link between brain size and intelligence is not absolute. Although modern human brains average about 1350 cc in size, they may range any where from under 1,000 cc to over 2,000 cc without any difference in intelligence or linguistic ability.

According to one account, the nineteenth-century Russian author Ivan Turgenev had a cranial capacity of 2,012 cc, as measured after his death, whereas Anatole France had barely 1,000 cc of headspace.

The brains of human females tend to be average 100 – 150 cc smaller than those of human males, a difference that is related to the difference in their body size, but this does not result in a different in intelligence.

By itself, cranial capacity does not determine the intelligence of an individual; rather, it is the development of different areas of the brain that determines intelligence, language ability, and related capacities.
Intelligence and brain