question: Why do girls have such big butts and thighs, while guys don’t?
comment: Men and women have different primary fat storage sites. Women tend to store fat on their thighs, hips, and butt first while men will store fat on their midsection first.
passages: Gross measures of body strength suggest that women are approximately 50-60% as strong as men in the upper body, and 60-70% as strong in the lower body. One study of muscle strength in the elbows and knees—in 45 and older males and females—found the strength of females to range from 42 to 63% of male strength. Another study found men to have significantly higher hand-grip strength than women, even when comparing untrained men with female athletes. Differences in width of arm, thighs and calves also increase during puberty.
  
  Section::::Respiratory system.
   Compared to males, females generally have relatively narrow waists and large buttocks, and this along with wide hips make for a wider hip section and a lower waist–hip ratio.
   Section::::Female counter-adaptations.
  
  Section::::Female counter-adaptations.:Anatomical protection.
  
  As a response to sexual coercion and the costs that females face, one of their counter-adaptations is the evolution of anatomical protection. Females of some species, such as the water striders, developed morphological shields to protect their genitalia from males that want to forcefully copulate. Some Gerridae females have also evolved abdominal spines and altered the shapes of their abdomens to make them less accessible to males.
   In contrast, the pelvis of the human male appears to be slightly narrower. It is believed that this makes it more optimized for walking and that an even wider female pelvis would have made walking more difficult; yet, more recent research tends to disprove this.
  
  The following further generalizations have been made regarding male-female skeletal differences:
  
  BULLET::::- Males in general have denser, stronger bones, tendons, and ligaments.
   Legs are used for standing, and all forms of locomotion including recreational such as dancing, and constitute a significant portion of a person's mass. Female legs generally have greater hip anteversion and tibiofemoral angles, but shorter femur and tibial lengths than those in males.
  
  Section::::Structure.
   Section::::Skeleton and muscular system.:Skeleton.
  
  The female skeleton is generally less massive, smoother, and more delicate than the male; its rib cage is more rounded and smaller, its lumbar curve greater, and a generally longer and smaller female waist results from the chest being more narrow at the base, and the pelvis generally not as high.
   Estrogen causes fat to be stored in the buttocks, thighs, and hips in women. When women reach menopause and the estrogen produced by ovaries declines, fat migrates from their buttocks, hips and thighs to their waists. Later fat is stored in the belly. Thus females generally have relatively narrow waists and large buttocks, and this along with wide hips make for a wider hip section and a lower waist-hip ratio compared to men. Hormonal and genetic factors may produce male-like distribution of fat in women i.e. around the belly instead of buttocks and thighs.
   The human skeleton performs six major functions; support, movement, protection, production of blood cells, storage of minerals, and endocrine regulation.
  
  The human skeleton is not as sexually dimorphic as that of many other primate species, but subtle differences between sexes in the morphology of the skull, dentition, long bones, and pelvis exist. In general, female skeletal elements tend to be smaller and less robust than corresponding male elements within a given population. The human female pelvis is also different from that of males in order to facilitate childbirth. Unlike most primates, human males do not have penile bones.
  
  Section::::Skeletal divisions.
   The pelvis is, in general, different between the human female and male skeleton. It differs both in overall shape and structure. The female pelvis, adapted for gestation and childbirth, is less high, but proportionately wider and more circular than in the male; its sacrum—the triangular bone at the upper posterior of the pelvic cavity, serving as base of the spine—is also wider. The female pelvis is tilted anteriorly, often resulting in the more sway-backed appearance.
   Anatomical differences between human males and females are highly pronounced in some soft tissue areas, but tend to be limited in the skeleton. The human skeleton is not as sexually dimorphic as that of many other primate species, but subtle differences between sexes in the morphology of the skull, dentition, long bones, and pelvis are exhibited across human populations. In general, female skeletal elements tend to be smaller and less robust than corresponding male elements within a given population. It is not known whether or to what extent those differences are genetic or environmental.
  
  Section::::Sex differences.:Skull.
   Females in general have lower total muscle mass than males, and also having lower muscle mass in comparison to total body mass; males convert more of their caloric intake into muscle and expendable circulating energy reserves, while females tend to convert more into fat deposits. As a consequence, males are generally physically stronger than females. While individual muscle fibers have similar strength between male and female, males have more fibers as a result of their greater total muscle mass. Males remain stronger than females when adjusting for differences in total body mass, due to the higher male muscle-mass to body-mass ratio. The greater muscle mass is reported to be due to a greater capacity for muscular hypertrophy as a result of higher levels of circulating testosterone in males.
   Long bones are generally larger in males than in females within a given population. Muscle attachment sites on long bones are often more robust in males than in females, reflecting a difference in overall muscle mass and development between sexes. Sexual dimorphism in the long bones is commonly characterized by morphometric or gross morphological analyses.
  
  Section::::Sex differences.:Pelvis.
   When women reach menopause and the estrogen produced by ovaries declines, fat migrates from their buttocks, hips and thighs to their waists; later fat is stored at the abdomen.
  
  Body fat percentage recommendations are higher for females, as this fat may serve as an energy reserve for pregnancy. Males have less subcutaneous fat in their faces due to the effects of testosterone; testosterone also reduces fat by aiding fast metabolism. The lack of estrogen in males generally results in more fat being deposited around the waist and abdomen (producing an "apple shape").
  
  Section::::Physiology.:Muscles.
   In less male-biased scenarios, a male’s tongue length plays an essential role in sexual selection. Dimensions of the copperhead pit viper, "Agkistrodon contortrix", show a significant tongue size difference, with males having a greater tongue bifurcation length, supporting the hypothesis that sexual selection is acting on tongue size in male snakes in order to enhance their ability to locate a potential female mate.
  
  Section::::Pheromonal cues.:In lizards.
  
  Females can determine a male's fitness based on the pheromones he leaves in an environment. These chemical cues inform females of a male’s quality,
   BULLET::::- Spoon: The hip measurement is greater than the bust measurement. The distribution of fat varies, with fat tending to deposit first in the buttocks, hips, and thighs. As body fat percentage increases, an increasing proportion of body fat is distributed around the waist and upper abdomen. The women of this body type tend to have a relatively larger rear, thicker thighs, and a small(er) bosom.
  
  BULLET::::- Hourglass or X shape (triangles opposing, facing in):
   BULLET::::- Women show higher performance levels on tests of verbal fluency. This may be because the female auditory cortex is more dense than that of the male. This difference and other sensory differences like it could be because of the sex hormones that impact the fetal brain during development.
  
  Section::::Tissues and hormones.
  
  BULLET::::- Women generally have a higher body fat percentage than men, whereas men generally have more muscle tissue mass.
  
  BULLET::::- Women usually have lower blood pressure than men, and women's hearts beat faster, even when they are asleep.
   Males and females differ in the following general components of fitness, thus leading to sexual conflict. Refer to the accompanying figure in this section.
   Before puberty both males and females have a similar waist–hip ratio. At puberty, a girl's sex hormones, mainly estrogen, will promote breast development and a wider pelvis tilted forward for child bearing, and until menopause a woman's estrogen levels will cause her body to store excess fat in the buttocks, hips and thighs, but generally not around her waist, which will remain about the same size as it was before puberty. These factors result in women's waist–hip ratio (WHR) being lower than for males, although males tend to have a greater upper-body to waist-hip ratio (WHR) giving them a V shape look because of their greater muscle mass e.g. they generally have much larger, more muscular and broader shoulders, pectoral muscles, teres major muscles and latissimus dorsi muscles.
   The femur is the only bone in the upper leg. The two femurs converge medially toward the knees, where they articulate with the proximal ends of the tibiae. The angle of convergence of the femora is a major factor in determining the femoral-tibial angle. Human females have wider pelvic bones, causing their femora to converge more than in males. In the condition "genu valgum" (knock knee) the femurs converge so much that the knees touch one another. The opposite extreme is "genu varum" (bow-leggedness). In the general population of people without either "genu valgum" or "genu varum", the femoral-tibial angle is about 175 degrees.
   There exist several general differences between the male and female skeletons. The male skeleton, for example, is generally larger and heavier than the female skeleton. In the female skeleton, the bones of the skull are generally less angular. The female skeleton also has wider and shorter breastbone and slimmer wrists. There exist significant differences between the male and female pelvis which are related to the female's pregnancy and childbirth capabilities. The female pelvis is wider and shallower than the male pelvis. Female pelvises also have an enlarged pelvic outlet and a wider and more circular pelvic inlet. The angle between the pubic bones is known to be sharper in males, which results in a more circular, narrower, and near heart-shaped pelvis.
   BULLET::::- On average, men are taller than women, by about 15 cm (6 inches). American males who are 20 years old or older have an average height of 176.8 cm (5 ft 10 in). The average height of corresponding females is 162 cm (5 ft 4in).
  
  BULLET::::- On average, men have a larger waist in comparison to their hips (see waist-hip ratio) than women.
  
  BULLET::::- Women have a larger hip section than men, an adaptation for giving birth to infants with large skulls.
  
  BULLET::::- In women, the index and ring finger tend to be the same length, whereas men's ring finger tends to be longer.
  
  Section::::Skeleton and muscular system.
   The principal differences between male and female true and false pelvis include:
  
  BULLET::::- The female pelvis is larger and broader than the male pelvis which is taller, narrower, and more compact.
  
  BULLET::::- The female inlet is larger and oval in shape, while the male sacral promontory projects further (i.e. the male inlet is more heart-shaped).
  
  BULLET::::- The sides of the male pelvis converge from the inlet to the outlet, whereas the sides of the female pelvis are wider apart.
   The association found between female fertility and sexual swelling size in several species of macaque offers support for this hypothesis. Specifically, females of low fertility, such as adolescents, exhibited substantially larger swellings than adults of a higher fertility level. Research remains fairly consistent across animal species; female yellow baboons ("Papio cynocephalus") who struggle to conceive are, on average, those that display the most prominent sexual swellings. In contrast, some have been critical of the sensory exploitation theory; they uphold the belief that, if female sexual swellings were not honest signals of female fertility, males would have evolved to identify differences in female quality or to have equal preference over females with different swelling sizes.
   The most obvious differences between males and females include all the features related to reproductive role, notably the endocrine (hormonal) systems and their physiological and behavioral effects, including gonadal differentiation, internal and external genital and breast differentiation, and differentiation of muscle mass, height, and hair distribution. There are also differences in the structure of specific areas of the brain. For example, on average, the SDN (INAH3 in humans) has been repeatedly found to be considerably larger in males than in females.
  
  Section::::Psychology.
   BULLET::::- Women are more likely to suffer from osteoarthritis and osteoporosis. The density of bones depends upon the stresses that are put on them through exercise. Exercise and activity in childhood helps to build up higher density bones. Although in Britain women's bones are less dense even before menopause, in some African societies, men and women are equally susceptible to osteoporosis.
  
  Infectious disease prevalence varies - this is largely due to cultural and exposure factors. In particular the WHO notes that:
  