From my research, I have come to believe that humankind has evolved four broad primary styles of thinking and behaving, each associated with one of four universal brain systems: the testosterone, estrogen, serotonin, and dopamine systems. Each of us is a unique mix of all of these, of course, but we express the traits of some more than others. Hence those who are particularly expressive of traits linked with testosterone I call Directors; those primarily expressive of estrogen I call Negotiators; of serotonin, Builders; and of dopamine, Explorers. …

Obama and Romney share several of the Director traits, but beyond these, their similarities end. …

Testosterone: Obama and Romney Score High

Much is known about testosterone and its effects on behavior. As fetal testosterone washes over the developing brain, it enhances visual and spatial perception, and builds the capacity for deep but relatively few interests and a keen understanding of “rule-based systems,” from mechanics to computers, math, engineering, or music. This is Romney to a T. …

Obama shares some of Romney’s testosterone-linked traits. Some regard him as aloof, a variation of “emotional containment.” Both men also tend to be self-confident, assertive, independent, and competitive. Scott writes that to Romney, a game of pickup basketball in the driveway almost always turns into a “blood sport”; Obama is apparently equally competitive, even in a game of tennis with Michelle. Additionally, both men appear to be acutely analytical, exacting, and data-driven—all traits linked with elevated-testosterone activity.