Final answer:
The individualistic theories in terms of body composition proposed by William Sheldon include three somatotypes: endomorphs, characterized by a rounder physique with more body fat; ectomorphs, known for a lean build and difficulty in gaining weight; and mesomorphs, which are naturally muscular with a high metabolism.
Step-by-step explanation:
The individualistic theories related to modern biological theories, specifically concerning somatotypes, were proposed by William Sheldon. He theorized that human body shapes could be classified into three distinct types:
- Endomorphs - Characterized by a higher proportion of body fat, softer body, rounder shapes, and difficulty losing weight.
- Ectomorphs - Known for their lean build, long limbs, and small muscle and fat storage; they often have trouble gaining weight.
- Mesomorphs - Typically muscular and well-built, with a high metabolism and responsive muscle cells, making it easier to gain and maintain muscle.
These somatotypes are related to physiological and genetic factors that influence an individual's body composition and psychology.