We don’t know everything about the brain (the saying goes that, "If the brain were so simple we could understand it, we would be so simple we couldn't"), but we do know some things. First, we know that a large brain does not mean that you are going to be borderline Tony Stark intelligent (or Stephen Hawking, or Albert Einstein, or Marie Curie… you get the idea). There is no correlation between brain size and intelligence. Second, the brain is, quite possibly, the most complex machine that we've ever encountered. It can’t be comprehensively labeled or understood through analyses of things like density, size, weight, etc. because those things are such a small portion of what the brain truly is—An electrical and chemical machine.

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Yet, there are a number of individuals who, because of a misunderstanding of random factoids about brain size and weight, have a false understanding of the brain.

For example, people frequently debate which sex is smarter, men or women; however, anyone who truly understands the complexity of the brain (and biology) knows that this debate is silly for a number of reasons. To illustrate this point: People frequently infer that men must be smarter because they have larger brains; however, according to this inference, we should assume that Neanderthals were rather bright and intelligent—more intelligent than us, in fact—because their brains (according to our best estimates) were a bit larger than the average humans.

Thus, Neanderthals should have been smarter than modern individuals; however, this does not seem to be the case.

Ultimately, it is important to understand just how complex the brain truly is so that we can avoid making unjust inferences or assumptions like the aforementioned. And to understand how the brain works in relation to sex, you need to get inside the brain and also understand how sex works on a genetic level.

Problems With the Sex Binary

To tackle this issue, first, we need to understand the complexity of biological sex. To begin with, the world is not divided between men and women; this is a false binary.While it’s true that most women have two X chromosomes and most men have one X chromosome and one Y chromosome, it is not universally true. A number of individuals have a combination of male/female phenotypical and genotypical presentation. Estimates assert that, in the United Sates, 2% people do not conform to XX or XY type.  If we extrapolate that data and apply it worldwide, that means that there are millions of people who and neither biologically male or biologically female.

So it’s erroneous to say that "men are smarter" or "women are smarter" because such statements exclude a number of individuals.

And this is just the very beginning of a discussion on the complexity of biological sex; however, the aforementioned should serve to illustrate an important point: Our genetic makeup (including the genetics of our biological sex) is far too complicated to group people in the way that we do—in terms of the male/female binary—and thus, as was mentioned, asserting that one sex is smarter is faulty on the basis of genetics alone. But that's not all...

Problems with the Brain's Complexity

Second, as I previously mentioned, the brain is not simple. There are a number of different kinds of intelligence. So even if we could break the world into the simple binary of men and women (we can’t), and we could definitively say that men are better with numbers and women are better at verbal tasks (we can't), how could we use this information to state who is smarter? Wouldn’t any such claim about number or words be entirely subjective?

Yes, it would.

Ultimately, simple assertions about the correlation between sex and intelligence leave much of the connection between biology and the brain unexplained. So, what can we say about sex and how this aspect of human biology impacts the brain?

Differences Between Men And Women

In 2001, researchers from Harvard found that certain parts of the brain were often (but not always) different sizes in people with XX chromosomes and people with XY chromosomes (generally speaking, women and men). The study found that parts of the frontal lobe (the part of the brain responsible for problem-solving and decision-making) and the limbic cortex (responsible for regulating emotions) were larger in women. In men, the parietal cortex (which is involved in space perception) and the amygdala (which regulates sexual and social behavior) were larger.

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Men also have approximately 6.5 times more gray matter in the brain than women BUT women have about 10 times more white matter than men do. Using a computer network as an analogy, the gray matter can be thought of as the actual computers, whereas the white matter represents the network cables connecting the computers together. Hence, women have more connections and they are more reinforced. Some women may have as much as 12% more neurons than men. This generally means that women should be faster at processing information; however, this is not an established rule, as individuals' brains are greatly impacted by the way that they are nurtured.

Studies have also shown that men and women access different areas of the brain to complete the same tasks. When asked to sound out words, men accessed the left side more while women accessed the right. Yet, both sexes completed the task just as well, which shows that there are a number of ways that the brain can effectively complete tasks.

The Main Point On Sex And Brain Size

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This is just the tip of the iceberg. There is a lot more to know about the brain and how it is impacted by things like sex, environment, age, the way it is nurtured, etc. But regardless of how differently men and women may think (in relation to the biological way that the brain functions), men and women both have about the same average score in relation to testing. Thus, as far as we can tell, neither sex is smarter. However, perhaps the main take away from all of this is that reductive statements are generally a red flag--a clear indicator of bad science.

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