Bad to the Bone: All About Criminal Motivation

"The streets are safe in Philadelphia, it's only the people who make them unsafe," Frank Rizzo, ex-police chief and former mayor of Philadelphia

Does the way we look have anything to do with the way we behave? Do our bodies predispose us to a predictable behavioral pattern? An American psychologist named William Sheldon (1898-1977) thought so. For decades, Sheldon examined the relationship between physical attributes and personality development. In 1940, Sheldon studied several hundred juvenile offenders in Boston, paying close attention to the structure of their bodies. He took thousands of photographs of naked young men, both frontal and profile view. Based on his meticulous observations, Sheldon managed to classify the body structures of these offenders into three general but distinct categories. The groups consisted of mesomorphs, who had a stocky, muscular build, ectomorphs who were thin and fragile and finally endomorphs who were described as soft, round with short limbs.

Full body image of Charles Starkweather,
Carryl Chessman and Albert DeSalvo
(CORBIS)

Sheldon used an ingenious numerical scale to grade the varying degrees of these characteristics in each individual. He recognized that people could possess varying degrees of each body build. He assigned a number of 1 through 7 to measure the amount of each type. Thus, a "pure" mesomorph would be a 7-1-1 type. A "pure" ectomorph would be a 1-7-1. A person with traits of both body types could be a 2-6-1 and so on.

Sheldon then interviewed hundreds of men and divided their personality characteristics into three categories. Sheldon believed that each body type had a corresponding and predictable personality profile.

• endotonia which was the love of physical comfort, food and socializing
• mesotonia which was the love of physical action and ambition
• ectotonia which centers on privacy and restraint

Sheldon found that there was a strong correlation between mesotonia and mesomorphs. The body type that was muscular and angular meshed with an action-loving, aggressive personality. Sheldon concluded this type of person, which he called mesotonic, most often descended into criminality. They slept the least, had higher blood pressure and were quick to anger. They were prone to gambling and very assertive in their dealings with others. Examples of the mesotonic could be found in every American prison and Sheldon saw this as a confirmation of his theories. It was easy for criminologists to point to people such as serial killer Charles Starkweather, Carryl Chessman, "The Red Light Bandit," Billy "Hard Luck" Cook, Albert DeSalvo, the alleged Boston Strangler, and many more who fit Sheldon's profile of the mesotonic criminal. Other criminals who did not fit the mesotonic parameters were simply ignored.

But psychologists were not convinced. For every mesotonic that committed crimes, there were just as many who did not. And there were many overweight criminals in jail. Sheldon's research remained mostly unproven, although his observations on body types and personalities provided a massive framework for a generation of researchers.