After Part 1 you're all wondering: why is this? I already explained why the difference are there, looking at evolution (it's because men are made for fighting and hunting and women for caring for babies and the social group). But then, how does the brain become what it should be in men/women? Is this difference present from birth or only later on?
Certain hormones, we call them 'sex hormones', start influencing a certain individual when it's still developing itself as a fetus. A study by Isreali researchers found that a male fetus, just 26 weeks old, shows a significant difference in brain from a female fetus. The disparities are found in the corpus callosum (bridge between left and right hemisphere), which in the brain of the female is much thicker than in the brain of the male. This is due to the fact that females use both their hemispheres, while males use mostly left.
Until puberty, girls continue to outperform boys in the use of language and fine motor skills. Boys show superiority over girls when it comes to math and geometry. These areas mature about four years earlier in boys than in girls. A recent study concluded that the brain of a 12-year-old-girl resembles that of an 8-year-old boy (when it comes to math). The specialities of the girls though, language and fine motor skills (such as handwriting), mature about six years earlier.
Also, after puberty, males contain about 6.5 times more gray matter ('thinking matter') than women, while female brains contain about 9.5 times more white matter('connecting matter'). But even more relevant is the fact that the frontal area and temporal area of the cortex are much more precisely organized in women (and bigger). Because this explains the fact that girls often call boys 'immature' or 'childish'. The lobes that 'make you mature' are much bigger, better organized, and earlier completed in women than in men.
Nature vs Nurture
But is it all nature? Nope. It all depends on how men and women use their special mental skills.
Have you ever been wondering 'why doe females always feel the need to gossip?!'. As stated earlier, females have a more sophisticated area for dealing with language. And therefore, they use it a lot. And by using it, it becomes even more refined. So at the end it will be this 'huge area'. If a woman just doesn't speak very much because of her character or other circumstances, this area would not develop this much. And again, why this is can be explained via evolution or nurture in the first place. Women used to have the job to take care of children and establish relationships between social groups so they could stay alive.
And we could also look at it as 'you gotta make do with what ya got'. For example, when giving someone directions, men use a completely different part of the brain than women. Women use the cerebral cortex, and mostly rely on landmark cues ('turn right at the supermarket'), while men use a nucleus deep inside the brain, in the left hippocampus, and mostly rely on the spatial aspect (depth reckoning, 'go west here').
And then we haven't even talked about emotions yet. Women are faster and more accurate at identifying emotions. Coming with that, is the ability to be more adept than men at encoding facial differences and determining change in vocal intonation (which explains why it seems as if every woman can sing amazingly well).
But then there is a surprising twist when it comes to what almost everybody thinks 'women just have much more emotions than men'. This is not true. Women actually have a much greater control of aggression and anger than men. Men just don't show their emotions, it's weak, and therefore they always hide it, though their initial reaction to something is much heavier. Women on the other hand control their emotions and only show what is 'useful' or 'can't hurt' but are also most of the time much softer in reacting when someone has done something wrong.
What do we have in common?
A lot, actually. Almost everything. Not only is every brain different, and there are men with lots of emotional control, and women with more than average spatial-skills.
Take for example the spatial-skills. Every part of the brain can be improved, but how the spatial part? Well, by just walking through space. Doing sports. And boys get to do that much more than girls, which gives them a great advantage therefore. If we'd treat girls and boys the same, they'd eventually become the same is the theory. Which is quite logical actually, and has research to prove it.
But then people raise the question: do we want that? I mean, isn't what nature has done for us enough? Don't men and women complement each other?
They do, and many people believe that it's best for men to stay men and women to stay women, because joined together this will have lots of advantages. But more on this psychological part, in Part 3.