Primary & Secondary Sexual Characteristics
- Sexual reproduction differs from asexual reproduction in that it takes two organisms to create offspring. Organisms that reproduce asexually create offspring by copying their genetic material and making clones of themselves. Species that reproduce sexually combine the genetic material of both organisms, creating offspring that have genes from the two parents. Sex characteristics allow this genetic exchange as well as help organisms of the same species identify sexual partners.
- Primary sex characteristics are also known as sex organs, and they are the parts of an organism's body that actively aid in sexual reproduction. Organisms that reproduce sexually have both male and female versions, and each sex has its own particular set of primary sex characteristics, different from the other sex. These characteristics can be external, such as the pistils of a flowering plant, or internal, such as the ovaries found in female mammals.
- Secondary sex characteristics have no specific reproductive purpose, but they differentiate between members of opposite sexes within a species. These can serve no specific purpose in relation to the species's sex and merely be an indicator of sex, such as facial hair on human men. Some species, however, may use secondary sex characteristics to emphasize their attractiveness to members of the opposite sex. Therefore, the secondary characteristics serve an important role in the overall reproductive process. Male peacocks, for example, use their elaborate feathers in this manner to attract female peacocks as partners.
- Primary sex characteristics in a human male include the testes, penis, scrotum and vas deferens, all of which directly aid in the transmission of the male's genetic material in the form of sperm to a female. Male secondary secondary sex characteristics in humans include facial hair and the Adam's apple. Men also typically have wider shoulders and more muscular upper bodies.
Primary sex characteristics in human females include the ovaries, fallopian tubes, uterus and vagina, all of which allow females to bear children. Secondary sex characteristics on human females include prominent breasts and mammary glands. Women also typically have wider, rounder hips and less muscular bodies.
