Researchers are saying that having big brains means you are extra smart - after all, you've got all the extra grey matter for help. And all this while, we thought that being nicknamed "thick-headed" was an insult!
For a long time now, researchers have been unearthing conflicting evidence regarding where intelligence lies in the brain. For example, in 2000, researchers in England and Germany discovered that intelligence seemed to depend exclusively on the brain's frontal lobes.
"That was a bit surprising," Live Science quoted neuroscientist and psychiatrist Sherif Karama at the Montreal Neurological Institute, as saying.
"It was hard to understand why something as complex as intelligence was restricted to just a few places in the brain," the expert added.
After some years later, other teams of investigators found signs that intelligence was based in other parts of the brain. However, there was one problem with all these experiments -they each looked at relatively small numbers of children.
To finish off the debate, using MRI Karama and his colleagues scanned the brains of 216 healthy boys and girls ages 6 to 18 from a range of ethnic groups and socioeconomic statuses.
The kids were also made to take intelligence exams testing analogies, vocabulary, reasoning and visual-spatial skills.
From the analyses, boffins discovered that intelligence was linked in general to the thickness of the "grey matter" - the cerebral cortex of the brain, which plays a key role in memory, thought, language and consciousness.
"It's not just a few regions. It's dispersed all throughout, in the areas associated with integrating information coming from diverse areas of the brain, which makes sense," Karama said.
The expert explained that if one looked at the average thickness of the cortex in these children, the differences between the lowest and highest IQs is on the order of a half-millimeter.
Karama stressed these findings do not mean that cortex thickness - or intelligence - is based solely on genetics.
Environment plays a role, to be sure," he said.
"You could help treat a lot of cognitive decline," Karama added.
The study has been published in the March-April issue of the journal Intelligence.