In his 1954 book, " Atlas of Men ", Sheldon categorised all possible body types according to a scale ranging from 1 to 7 for each of the three " somatotypes ", where the pure " endomorph " is 7 1 1, the pure " mesomorph " 1 7 1 and the pure " ectomorph " scores 1 1 7.
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American psychologist William Herbert Sheldon associates body types with human temperament types . Sheldon proposed that the human physique be classed 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 ).
