Somatotype and constitutional psychology
Somatotype is a taxonomy developed in the 1940s, by American psychologist William Herbert Sheldon, to categorise the human physique according to the relative contribution of three fundamental elements, somatotypes, named after the three germ layers of embryonic development: the endoderm, (develops into the digestive tract), the mesoderm, (becomes muscle, heart and blood vessels), and the ectoderm (forms the skin and nervous system).
Constitutional psychology is a now neglected theory, also developed by Sheldon in the 1940s, which attempted to associate his somatotype classifications with human temperament types. Sheldon and Earnest Hooton were seen as leaders of a school of thought, popular in anthropology at the time, which held that the size and shape of a person’s body indicated intelligence, moral worth and future achievement.
Comparison of body types
Ectomorphic: characterized as linear, thin, usually tall, fragile, lightly muscled, flat chested and delicate; described as cerebrotonic inclined to desire isolation, solitude and concealment; and being tense, anxious, restrained in posture and movement, introverted and secretive.
Mesomorphic: characterized as hard, rugged, triangular, athletically built with well-developed muscles, thick skin and good posture; described as somatotonic inclined towards physical adventure and risk taking; and being vigorous, courageous, assertive, direct and dominant.
Endomorphic: characterized as round, usually short and soft with under-developed muscles and having difficulty losing weight; described as viscerotonic enjoying food, people and affection; having slow reactions; and being disposed to complacency.
There is evidence that different physiques carry cultural stereotypes. For example, one study found that endomorphs are likely to be perceived as slow, sloppy, and lazy. Mesomorphs, in contrast, are typically stereotyped as popular and hardworking, whereas ectomorphs are often viewed as intelligent but fearful and usually take part in long distance sports, such as marathon running.