Many evolutionary biologists believe the increased in the size of the brain relative to the body size in animals such as primates was driven by the demands of living in societies. This is known as the social – or Machiavellian – intelligence hypothesis.
- Previous comparisons of different birds and primates have shown that more social animals tend to have larger brains.
- “Social interactions seem to impose important cognitive challenges that must be met by enhanced investment in certain brain regions”

Rex Jung at the University of New Mexico in Albuquerque and his colleagues had found that creativity correlates with low levels of the chemical N-acetylaspartate, which is found in neurons and seems to promote neural health and metabolism.
- Several recent studies have suggested that white matter of high integrity in the cortex, which is associated with higher mental function, means increased intelligence.
- Jung found that the most creative people had lower white-matter integrity in a region connecting the prefrontal cortex to a deeper structure called the thalamus, compared with their less creative peers.
- Jung suggests that slower communication between some areas may actually make people more creative.