For the first time, the Intellectual Quotient has been correlated with the size and performance of individual neurons. If confirmed, the finding could lead to new ways to improve human intelligence.
Why are there smarter people?
Most intelligence research, to date, has identified brain regions involved in certain abilities, or have identified hundreds of genes that play a very small role in determining IQ.
Now, Natalia Goriounova, at the Free University, Amsterdam, has gone a step further. The results of their study have been published in BioRxiv.
In the study, 35 people were analyzed who needed surgery for brain tumors or severe epilepsy. Each patient was subjected to an IQ test just before the operation. Then, while they were in surgery, small samples of healthy brain tissue were removed, and they were kept alive for analysis.
Examination of this tissue revealed that brain cells are significantly larger in people with higher IQ than those with lower scores. The larger cells also have more dendrites, the projections that connect to other neurons, and the dendrites are longer, which suggests that these neurons may be able to receive and process more information. As the researcher explains:
It is generally assumed that human intelligence relies on the efficiency with which neurons process information that enters the brain. And although it is assumed that human intelligence is related to the thickness of the gray matter of the temporal and frontal lobes, there was no scientific evidence linking the physical and structural properties of neurons with intelligence.
It is still unclear why some people have bigger brain cells than others (we do not know if the differences are the result of experience, or if they are biologically determined), or whether this is a cause or a consequence of a high IQ.
The next step would be to have a higher sample size, because 35 people are few examples; However, given that it is difficult to study living brain tissue, we will soon see more extensive studies in this regard.