Since around 200 years ago scientists have been carrying out experiments on whether the size of the brain correlates with our intelligence or not. To which the results were: yes!!! But, the volume of the brain plays a very marginal role.

Relating to human beings, men, in average, have 10% bigger brains than women – 130 grams more, which is the mass of a half package of butter – but they are not smarter than women regarding their Intelligence Quotient (IQ) or general intelligence.

If we look at sub-aspects of the brain volume in detail, the grey matter in areas of the cortex and white matter in the basal ganglia, and therefore the number of neurons seem to be the most relevant in correlation to a person’s intelligence.

This might be that more neurons simply mean that there are more possibilities to connect cognitive networks which you could compare to Lego – where the more stones you have, the more options you have to build up the right solution for a problem… But like many things in life, even within our brain, quality seems to be important rather than quantity.

How well working the connections between our neurons are decides which information gets easily transferred to where and where not which are important for processing information on which our thinking power is based on. In this process, another important thing to know is how strongly the neurons are covered with Myelin, e.g. how well they are electrically isolated since that is speeding up the transfer of information.

And last but not least, it’s significant how well the grey matter is, as even in healthy people lesions or micro bleedings get repeatedly observed. This might affect the intelligence negatively.

Though all of this explains maybe merely 20%  of the differences in intelligence.

The remaining 80% still need a clarification…