Does Everyone Have Equal Brain Power?

Are all memories created equal? It is virtually certain that different people have different brain abilities for different things. One of these differences must be in memory. But most of the differences in memory abilities that we see in everyday life do not seem to be due to differences in the brains we are born with, but to differences in how well we use the brains we are born with.

Our brains are probably somewhat like our muscles: everybody is born with different amounts of muscle. And this is probably particularly true of the muscle that is your heart. So it is likely that some people have bigger, stronger hearts than others do at birth. But it is also true that many people can take whatever amount of heart they are born with - large or small—and train themselves up from couch potato to marathon runner. The differences we find in everyday memory probably are comparable. They are probably still mostly based on how much we exercise what we have, not how much memory we are born with.

This is not to minimize the fact that different people may be born with different memory abilities. We know or suspect that there are genetically-based differences in brains. Some of the evidence comes from identical twins. Identical twins are almost exactly alike in their genetic composition. And identical twins show remarkably similar intelligence and memory abilities, even when they have been separated at birth and reared by different parents, in different environments. They even show remarkably similar patterns of how those intellectual abilities develop childhood and adolescence. These similarities suggest that there is a genetic program for intelligence and memory, that partly determines the intelligence and memory that we have in later life.

At the brain level, less is actually known about actual individual differences in the brain, and even less is known about individual differences in nerve cell connections. But these also certainly exist. One known example: an area of the cortex of the brain - the gray matter - is the first stop for information coming from the eyes. This area of the brain is clearly important in vision. Species with good vision have more of it; species that lose their vision (such as some that live in caves without light) lose this brain region. In humans, on the average, this brain region is three to four times larger than it is in monkeys - some reflection of our superior brain power, we would hope. But we also know that in some people, this area can be three times larger than it is in other people.