Sexologist
Alfred Kinsey has suggested that the buttocks are the primary sexual presentation site in
primates. Some anthropologists and sociobiologists believe that
breast fetishism derives from the breasts' similarity to buttocks, but instead provide sexual attraction when the body is seen from the front. In humans, females generally have rounder and fuller buttocks compared to males, caused by
estrogen that encourages the body to store fat in the buttocks, hips, and thighs.
Testosterone discourages fat storage in these areas. The buttocks in human females thus contain more
adipose tissue than in males, especially after
puberty.
Evolutionary psychologists suggest that rounded buttocks may have evolved as a desirable trait because they provide a visual indication of the woman's youth and fertility. They signal the presence of estrogen and the presence of sufficient fat stores for
pregnancy and
lactation. Additionally, the buttocks give an indication of the shape and size of the
pelvis, which impacts reproductive capability. Since development and pronunciation of the buttocks begins at
menarche and declines with age, full buttocks are also a symbol of youth. In a 2017 study, using 3D models and eye-tracking technology, Fisher's claim was tested and was shown that the slight thrusting out of a woman's back influences how attractive others perceive her to be and captures the gaze of both men and women. Bobbi S. Low et al. said that the female buttocks "evolved in the context of females competing for the attention and parental commitment of powerful resource-controlling males" as an "honest display of fat reserves" that could not be confused with another type of tissue, although
Tim M. Caro rejected that as being a necessary conclusion, stating that female fatty deposits on the hips improve individual
fitness of the female, regardless of
sexual selection. ==History==