In humans they also have a role in propelling the body in a forward motion and aiding bowel movement. In the case of humans, females tend to have proportionally wider and thicker buttocks due to higher subcutaneous fat and proportionally wider hips. Females of certain species of baboon have red buttocks that blush to attract males. The buttocks allow primates to sit upright without needing to rest their weight on their feet as four-legged animals do. The masses of the gluteus maximus muscle are separated by an intermediate intergluteal cleft or 'crack' in which the anus is situated. The gluteus maximus has two insertion points: 1⁄ 3 superior portion of the linea aspera of the femur, and the superior portion of the iliotibial tractus. The superior aspect of the buttock ends at the iliac crest, and the lower aspect is outlined by the horizontal gluteal crease. The buttocks are formed by the masses of the gluteal muscles or 'glutes' (the gluteus maximus muscle and the gluteus medius muscle) superimposed by a layer of fat. The English language is replete with many popular synonyms that range from polite colloquialisms ('posterior', 'backside' or 'bottom') to vulgar slang ( 'arse', 'ass', 'bum', 'butt', 'booty', 'prat'). There are several connotations of buttocks in art, fashion, culture and humor. Many cultures have also used the buttocks as a primary target for corporal punishment, as the buttocks' layer of subcutaneous fat offers protection against injury while still allowing for the infliction of pain. In many cultures, the buttocks play a role in sexual attraction.

In the seated position, the buttocks bear the weight of the upper body and take that weight off the feet. They are responsible for movements such as straightening the body into the upright (standing) posture when it is bent at the waist maintaining the body in the upright posture by keeping the hip joints extended and propelling the body forward via further leg (hip) extension when walking or running. The two gluteus maximus muscles are the largest muscles in the human body. They are composed of a layer of exterior skin and underlying subcutaneous fat superimposed on a left and right gluteus maximus and gluteus medius muscles. In humans, the buttocks are located between the lower back and the perineum. The buttocks (singular: buttock) are two rounded portions of the exterior anatomy of most mammals, located on the posterior of the pelvic region.

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