Summary: long legs, wide shoulders, muscular, agile, 3. asthenic—tall, thin, nerve patterns apparent, and 4. leptosomic—also tall, but with normal body proportions. The second major scheme, the somatotonic, viscerotonic, and cerebrotonic types, was proposed by Sheldon and Stevens in 1942. They based their classification on three layers of the human embryo, the endoderm, mesoderm, and ectoderm, with each layer giving rise to certain physical and psychological traits. However, the practical utility and validity of such typologies have been frequently questioned, and more contemporary approaches to assessment emphasize multi-dimensional and personalized evaluations rather than rigid typings based on physical characteristics.