How boys’ and girls’ brains differ ?

In the last five years, a huge amount has been learnt about brain development, which may surprise and delight you.  Did you know that at birth, the brain is still only partially formed – and only a third of its eventual size? It takes a long time for the brain to be completed. For instance, the language part of the brain is not fully formed until about the age of thirteen.

From very early on, gender differences are evident in the unborn baby’s brain.  One difference is that a baby boy’s brain develops more slowly than a baby girl’s. Another difference is that the left and right sides form fewer connections in a boy.

All animal brains have two halves. In animals like lizards or birds, this means that everything is duplicated. A knock on the head might wipe out part of one half of the brain, but the other half can still take care of things! In humans however, the two brain halves specialize somewhat.  One half handles language and reasoning; the other movement, emotion and the sense of space and position. Both halves talk to each other through a big central bundle of fibers called the corpus callosum. The corpus callosum in boys is proportionality smaller in size – there are fewer connections running from one side to the other compared to girls.

It has been shown in recent studies that boys tend to approach certain kinds of problems using only one side of their brain, while girls use both sides. This can be seen using the brain-scanning technology of magnetic resonance (MRI). The ‘lights go on’ all over a girl’s brain when solving a problem. While in a boy, they tend to be localized on one part of one side only.

Why the difference?

The brain of a baby before and after birth grows rather like a vine.  Brain cells keep getting longer and making new connections all the time. The left half of the cortex grows more slowly than the right in all human babies, but in males it is even slower still. This is because the testosterone (the male hormone) in a boy’s bloodstream slows development down. Estrogen on the other hand, (the hormone that is predominant in the bloodstream of baby girls), actually stimulates faster growth of brain cells.

As the right half grows, it tries to make connections with the left half of the brain. In boys, the left half isn’t ready yet to take the connections, and so the nerve cells reaching across from the right side cannot find a place to attach. So they go back to the right side where they come from and attach there instead. As a result, the right half of a boy’s brain is richer in internal connections, but poorer in cross connections to the other half. This usually means that most boys have well developed spatial or mathematical intelligence, which relies on the right side of the brain; while communication, which is a left brain activity, is under-developed.