The truth about intelligence: Are bigheads smarter than pea brains? | AI
Over human evolutionary history, our brain size has increased dramatically as our cognitive capabilities have grown. Even among modern humans, brain size accounts for around 10 per cent of the difference in intelligence scores between individuals. Big brains may simply have more neurons and so greater processing power, or the neurons may possess more bulky insulating white matter, allowing them to communicate faster.
Nevertheless, when it comes to brains, size isn’t everything. “Neanderthals had bigger brains than we do, and they are extinct,” says Rex Jung at the University of New Mexico. “Men also have bigger brains than women. Does that mean men are smarter than women? Certainly not.”
In fact, brain structure is a more reliable marker of smarts than brain size. On average, women have thicker cortices – the wrinkly, outer layer of the brain, responsible for higher-level functions – and thicker cortices have been associated with higher IQ scores. “All the wrinkles and convolutions allow more of that computational capacity to fit in,” says Jung. Men, meanwhile, tend to have bigger sub-cortical regions, including the hippocampus, which is involved in memory and spatial awareness, and the amygdala, which handles emotions and decision-making, although that doesn’t necessarily correspond with greater skill in these areas. There is also more variability in these measurements between men than between women – interesting because, although there is no overall difference in intelligence between the sexes, men tend to be over-represented at both …