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Sex Difference In Humans: Currently Published

Introduction
Sex differences are also increased or decreased according to societal situations.

These differences and their extent vary across societies.

Sexual organs and reproductive organs
Female ejaculation is a phenomenon that has been observed for 2,000 years. it refers to the release of fluid experienced by some women at the high of pleasure. The components of the ejaculate are comparable to that of the male ejaculate. The release of this fluid is a product of the female prostate, located within the walls of the urethra. The female prostate is much smaller than the male prostate, but seem to behave similarly, although the female ejaculate does not contain sperm. The female prostate is visible through MRI and ultrasound.

Sex Determination and Differentiation
Chromosomes are not the final determinant of sex. In some cases, for example, chromosomally female babies that have been exposed to high levels of androgens before birth can develop masculinized genitals by the time they are born. There are other variations of sex chromosomes that lead to a variety of different physical expressions. .

Strength, Power and Muscle Mass
Typically in Western societies, males are physically stronger than females.

This is due to the fact that during childhood, both males and females use their leg muscles the same amount for activities like running, walking, and playing. The wider variation in upper-body strength is a socially created by the pressure on males to enhance their muscles. .

This sex difference does not apply to all human societies. In Bali, for example, where men do not usually participate in heavy work, there is less difference between the muscle mass of men and women. Even within Western societies, it is possible that the greater capacity for muscle development in men is a result of early gender expectations of young children, which become more prominent over the person's lifetime.

Differences in width of arm, thighs and calves also increase during puberty. Exercise can lower the degree of sex differentiation in muscle development as adults. For example, the amount of oxygen that the blood can carry is very similar in male and female athletes, while in untrained people women cannot carry as much oxygen.

Most statistics in the areas of strength, power, muscle mass, and height of human males and females is based on mean numbers, but these numbers are not exact representations of a society as they exclude information on the spread of the data. When considering the spread of most statistics, there is significant overlap in the values of physical straits between men and women. In addition, there are a significant number of individuals who deviate from from the average statistics.

Respiratory System
In athletes, the difference in oxygen-carrying capacity between men and women is much less prominant. This suggest that the higher capacity in untrained males than untrained females is the product of difference gender expectations in regards to physical development and activity.

Fertility
Women's physical experiences vary depending on external forces such as diet, marriage patters, culture, and other aspects. In Western nations menstruation begins to affect girls at 13 and menopause starts around 51. In non-industrialized countries, on the other hand, most women begin menstruation at 17 and menopause at 42. More lactation in the lifetime of non-western women inhibits ovulation and extends the number of fertile years.

Sensory Systems
Replication of these studies has been problematic, however. The conclusions draws from them are derivative of gender role expectations of pain and not sex differences. While most women expect to be less tolerant, men expect to be more tolerant and therefore report agitation later.

Life Span
The longer average life span of women can lead to skewed statistical results in regards to sex difference. For example, women are often seen to be at a higher risk for bone fracture due to osteoporosis. Although women do lose bone density faster than men after menopause, the data shows a larger disparity because there are more older women in the population.

Brain size
This study, which was undertaken after women's rights began to pick up speed in England, was shown to be flawed, however. The field of craniology had so much influence that the misconception still exists that any deference detected in the brain size of men and women is a viable indicator if intelligence. More recently, a 1992 study of 6,325 Army personnel found that men's brains had an average volume of 1442 cm³, while the women averaged 1332 cm³. Newer studies such as this are also not necessarily variable because of the underrepresentation of women in the military (about 14.4% of active duty members).

Genetic and Hormonal Causes
Other than external genitals, there are few physical differences before puberty. Small differences in height and start of physical maturity are seen. In the first decade of human life there is a significant amount of overlap between boys and girls. the gradual growth in sex difference throughout a person's life is a product of various hormones. Testosterone is the major active hormone in male development while estrogen is the dominant female hormone. These hormones are not, however, limited to each sex. Both males and females have both testosterone and estrogen.

Sexual Dimorphism
The current estimated rate for intersexuality is about 1 in 1500 to 1 in 2000 births. There are a greater number of individuals, however, who have a subtler variation of their assigned sex. These variations are not always present at birth. . Intersexuality is not often discussed or witnessed in Western culture because when an intersexual baby is born, surgery is usually performed within the first 24 hours to assign a sex to the baby. The existence of so many instances and types of intersexuality calls into question the Western conception of the gender binary. It has been suggested that gender may be better understood as a spectrum as opposed to a binary.

Differences not linked to sex chromosomes
The density of bones dependent 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.