Does Brain Size Matter?
A fascinating article in Cerebrum from the Dana Foundation makes the case that brain size matters by clarifying when and how the size of an animal’s brain makes a difference. But there are a lot of other differences as well. Here’s our take on key points from the article:
- In general, the larger an animal, the bigger its brain.
- In general, a bigger brain is correlated with greater cognitive functioning. That is, a species that has a larger brain than another species typically has great cognitive and behavioral range.
- However, there are other features of brains that distinguish different types of animals that are vitally important. It is not just about size!
- Some mammals and birds have greater cognitive function that the brain-size correlation would predict.
- The relative proportion of the brain that is comprised of the “forebrain,” (frontal lobes), especially the prefrontal cortex, is much larger in mammals with greater cognitive capacity. The prefrontal cortex is proportionately largest in humans.
- Humans also have relatively more neurons (the cells that communicate with each other) in the cortex than any other animal.
- The differences discussed in the article are differences between species. The article did not intra-species differences. To our knowledge, the difference in brain size within a species is not correlated with intelligence, but it is suggested that the number and strength of connections among neurons is related to cognitive function.
Dr. Jon Kaas, the author, is careful to point out that there is much we don’t know about the brains of humans and other species that neuroscience continues to seek to unravel.