The Biology of Personality

Chemical systems play a role in personality. We may have as many as a hundred different kinds of neurotransmitters (smaller molecules) and some fifty types of peptides in the brain. But most keep the heart beating or orchestrate other basic functions. Only dopamine, serotonin, testosterone and estrogen have been directly associated with a wide range of personality traits, they are involved in attention, mood, memory, and fine motor skills. So variations in these four chemicals most likely form the foundation of these four basic styles of thinking and behaving. These four chemicals play lead roles in producing aspects of personality.

 

Dopamine. A powerful and ubiquitous brain neurotransmitter chemical. The personality traits associated with specific genes in the dopamine system: the propensity to seek novelty; the willingness to take risks; spontaneity; heightened energy; curiosity; creativity; optimism; enthusiasm; mental flexibility. We can call those men and women who expressed the traits associated with this biology Explorers.

Individuals who have inherited particular genes in the serotonin system tend to be calm, social, cautious but not fearful, persistent, loyal, fond of rules and facts and orderly. They are conventional, the guardians of tradition. And because these men and women are also skilled at building social networks and managing people in family, business and social situations, we will dub those who had inherited this constellation of genetic traits Builders.

Although testosterone is often associated with males, we know that both men and women are capable of expressing particularly strong activity in this neural system. Moreover, those who inherit this chemistry tend to be direct, decisive, focused, analytical, logical, tough- minded, exacting, emotionally contained and good at strategic thinking. They get to the point. Many are bold and competitive. They excel at figuring out machines, mathematical formulas or other rule- based systems. Many are good at understanding the structure of music, too. We will these people Directors.

Last in our store of biological knowledge are some of the traits linked with estrogen. Estrogens are generated from cholesterol via testosterone in the ovaries, but also by the brain and by body fat deposits in both males and females. Women and men with a great deal of estrogen activity tend to see the big picture: they connect disparate facts to think contextually and holistically, expressing what we call web thinking. They are imaginative. They display superior verbal skills and excel at reading postures, gestures, facial expressions and tones of voice, known as executive social skills. They are also intuitive, sympathetic, nurturing, mentally flexible, agreeable, idealistic, altruistic and emotionally expressive. We will christen the people of this broad biological type Negotiators.

Other chemical systems play a role in personality, of course. We may have as many as a hundred different kinds of neurotransmitters (smaller molecules) and some fifty types of peptides in the brain. But most keep the heart beating or orchestrate other basic functions. It is increasingly apparent that these four chemicals -- dopamine, serotonin, testosterone and estrogen -- play lead roles in producing aspects of personality.

Two others should be mentioned, though. Norepinephrine, a chemical closely related to dopamine, undoubtedly contributes to some of the Explorer's traits, especially their energy and impulsivity. And oxytocin -- a chemical synthesized, stored and triggered (in large part) by estrogen -- most likely plays a role in the Negotiator's compassion, nurturing, trust and intuition. In fact, families of chemicals produce the Explorer, Builder, Director and Negotiator. The specific activities of any one chemical are not as significant as the ratios and interactions among all of them and several other neural systems.