In his 2013 book, Social: Why Our Brains are Wired to Learn, Matthew Lieberman described research from late in the 20th century that determined the default areas of brain activity. When a person stops trying to do something else, and the rest of the brain goes quite, the default areas are active. If one begins working one math problem, for example, the default area goes quite as the “math area” become more active, and once the math problem is solved, its part of the brain turns off and the default area is again active.
The default area of the brain, as it turns out, is that part that is active when one is engaged in social cognition which is thinking about “people, oneself, and the relation of oneself to others.” Our brains, it appears, prefer to think in social terms.