Will A Bigger Human Brain Play Better Chess?
The human brain is the largest brain of all vertebrates relative (in comparison) to the body size, and it weighs about 3.3 lbs. ie., 1.5 kilograms.
The incredible human brain is the one and only command center for the human nervous system. It receives signals from the body's sensory organs and outputs information to the muscles. The human brain has the same basic structure as other mammal brains but is much larger in relation (ratio) to the body size than any other brains. Does this have to do anything with better functioning and polished intelligence?
While “size does not matter” is a universally preached dictum among the politically correct, everyday experience tells us that this can’t be the whole story—under many conditions, it clearly does.
The prevailing rule of thumb holds that the bigger the animal, the bigger its brain. After all, a bigger creature has more skin that has to be innervated and more muscles to control and requires a larger brain to service its body. Thus, it makes sense to control for overall size when studying brain magnitude. By this measure, humans have a relative brain-to-body mass of about 2 percent. What about the big mammals—elephants, dolphins and whales? Their brains far outweigh those of puny humans, up to 10 kilograms for some whales. Given their body mass, ranging from 7,000 kg (for male African elephants) up to 180,000 kg (for blue whales), their brain-to-body ratio is under a tenth of a percent. Human brains are far bigger relative to people’s sizes than those of these creatures. Smugness is not in store, though. We are outclassed by shrews, molelike mammals, whose brain takes up about 10 percent of their entire body mass. Even some birds beat us on this measure. Hmm.
The human brain continues to grow until it reaches its peak size in the third to fourth decade of life. An MRI study of 46 adults of mainly European descent found that the average male had a brain volume of 1,274 cubic centimeters (cm3) and that the average female brain measured 1,131 cm3. Given that a quart of milk equals 946 cm3, you could pour a bit more than that into a skull without any of it spilling out. Of course, there is considerable variability in brain volume, ranging from 1,053 to 1,499 cm3 in men and between 975 and 1,398 cm3 in women. As the density of brain matter is just a little bit above that of water plus some salts, the average male brain weighs about 1,325 grams, close to the proverbial three pounds often cited in U.S. texts.
Removing brains after their owners died revealed that Russian novelist Ivan Turgenev’s brain broke the two-kilogram barrier, coming in at 2,021 grams, whereas writer Anatole France’s brain could barely bring half of that weight to the scale at 1,017 grams. (Note that postmortem measures are not directly comparable to data obtained from living brains.) In other words, gross brain size varies considerably across healthy adults.
What about smarts? We all know from our day-to-day interactions that some people just don’t get it and take a long time to understand a new concept; others have great mental powers, although it is impolite to dwell on such differences too much. Think of Bertie Wooster, an idle but clueless rich man, and Jeeves, his genius valet, in a series of novels by P. G. Wodehouse and their successful British adaptation to the small screen.
Some points to note :
1. Human brains vary considerably in size across adults, with males having slightly larger brains than females.
2. It is hard to pin down what makes the human brain exceptional among mammals—neither brain size, relative brain size nor number of neurons is unique to humans.
3. More intelligent people do better in life, but there is only weak correlation between brain size and intelligence, especially across species.
For more facts on the human brain, click here.
Individuals differ in their ability to understand new ideas, to adapt to new environments, to learn from experience, to think abstractly, to plan and to reason. Psychologists have sought to capture these differences in mental capacities via a number of closely related concepts such as general intelligence (g, or general cognitive ability) and fluid and crystalline intelligence. These differences in people’s ability to figure things out on the spot and to retain and apply insights that they learned in the past to current circumstances are assessed by psychometric intelligence tests. These observations are reliable, in that different tests strongly correlate with one another. They are also stable across decades. That is, measures such as the intelligence quotient (IQ) can be repeatedly and reliably obtained from the same subjects nearly 70 years later.
Differences in general intelligence, assessed in this way, correlate with success in life, with social mobility and job performance, with health and with life span. In a study of one million Swedish men, an increase in IQ by one standard deviation, a measure of variability, was associated with an amazing 32 percent reduction in mortality. Smarter people do better in life. Whereas a high IQ may not predispose people to be happy or to understand the finer points of dating, the highly intelligent are more likely to be found among hedge fund managers than among supermarket checkout clerks.
What about any numerical relation between brain size and intelligence? Such correlations were difficult to establish in the past when only pathologists had access to skulls and their content. With structural MRI imaging of brain anatomy, such measurements are now routine. In healthy volunteers, total brain volume weakly correlates with intelligence, with a correlation value between 0.3 and 0.4 out of a possible 1.0. In other words, brain size accounts for between 9 and 16 percent of the overall variability in general intelligence. Functional scans, used to look for brain areas linked to particular mental activities, reveal that the parietal, temporal and frontal regions of the cortex, along with the thickness of these regions, correlate with intelligence but, again, only modestly so. Thus, on average, a bigger brain is associated with somewhat higher intelligence. Whether a big brain causes high intelligence or, more likely, whether both are caused by other factors remains unknown.
Recent experiments take into account the particular connections among neurons in certain regions of an individual’s brain, much like a neural fingerprint. They do better at predicting fluid intelligence (the capacity to solve problems in novel situations, to find and match patterns, to reason independently of specific domains of knowledge), explaining about 25 percent of the variance in this measure from one person to the next.
Our ignorance when it comes to how intelligence arises from the brain is accentuated by several further observations. As alluded to earlier, the adult male’s brain is 150 grams heavier than the female’s organ. In the neocortex, the part of the forebrain responsible for perception, memory, language and reasoning, this disparity translates to 23 billion neurons for men versus 19 billion for women. As no difference exists in the average IQ between the two genders, why is there a difference in the basic number of switching elements?
It is also well established that the cranial capacity of Homo neanderthalensis, the proverbial caveman, was 150 to 200 cm3 bigger than that of modern humans. Yet despite their larger brain, Neandertals became extinct between 35,000 and 40,000 years ago, when Homo sapiens shared their European environment. What’s the point of having big brains if your small-brained cousins outcompete you?
For a detailed study on the size of the human brain, click here.
