Secondary sex characteristics are features that appear during puberty, especially those that distinguish the two sexes of a species, but that are not directly part of the reproductive system. They are believed to be the product of sexual selection for traits which give an individual an advantage over its rivals in courtship and aggressive interactions.]citation needed[ They are distinguished from the primary sex characteristics — the sex organs — which are directly necessary for reproduction to occur.
Well-known secondary sex characteristics include manes of male lions and long feathers of male peacocks. Other dramatic examples include the tusks of male narwhals, enlarged proboscises in male elephant seals and proboscis monkeys, the bright facial and rump coloration of male mandrills, and horns in many goats and antelopes. Male birds and fish of many species have brighter coloration or other external ornaments. Differences in size between sexes are also considered secondary sexual characteristics.
Pubic hair is the hair in the frontal genital area of adolescent and adult humans, located on and around the sex organs, the crotch, and sometimes at the top of the inside of the thighs, in the pubic region around the pubis bone.
Although fine vellus hair is present in the area in childhood, pubic hair is considered to be the heavier, longer and coarser hair that develops during puberty as an effect of rising levels of androgens. Pubic hair is therefore part of the androgenic hair (or body hair) and is a secondary sex characteristic.
The most accurate measurement of the human penis comes from several measurements at different times since there is natural minor variability in size due to arousal level, time of day, room temperature, frequency of sexual activity, and reliability of measurement. When compared to other primates, including large primates such as the gorilla, the human penis is largest, both in absolute terms and in relative size to the rest of the body.
Measurements vary, with studies that rely on self-measurement reporting a significantly higher average than those with staff measuring. However, the mean of an erect human penis is approximately 12.9–15.0 cm (5.1–5.9 in) in length. Flaccid penis length is a poor estimate of erect length.
The reproductive system or genital system is a system of sex organs within an organism which work together for the purpose of reproduction. Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system.[dead link] Unlike most organ systems, the sexes of differentiated species often have significant differences. These differences allow for a combination of genetic material between two individuals, which allows for the possibility of greater genetic fitness of the offspring.
Human sexuality is the capacity to have erotic experiences and responses. A person's sexual orientation may influence their sexual interest and attraction for another person. Sexuality can have biological, emotional/physical or spiritual aspects. The biological aspect of sexuality refers to the reproductive mechanism as well as the basic biological drive that exists in all species, which is hormonally controlled. The emotional or physical aspect of sexuality refers to the bond that exists between individuals, and is expressed through profound feelings or physical manifestations of emotions of love, trust, and caring. There is also a spiritual aspect of sexuality of an individual or as a connection with others. Sexuality impacts and is impacted by cultural, political, legal, and philosophical aspects of life. It can refer to issues of morality, ethics, theology, spirituality, or religion. Some cultures have been described as sexually repressive.
Interest in sexual activity typically increases when an individual reaches puberty. Some researchers assume that sexual behavior is determined by genetics, and others assert that it is molded by the environment. This is the nature versus nurture debate, in which one can define nature as those behavioral traits that are due to innate characteristics, such as instincts and drives. The concept of nurture can be defined as the environmental factors or external stimuli that influence behavior, emotions, and thinking. Biological and physical differences include the human sexual response cycle among men and women.
A social issue (also called a social problem or a social situation) is an issue that relates to society's perception of a person's personal lives. Different cultures have different perceptions and what may be "normal" behavior in one society may be a significant social issue in another society. Social issues are distinguished from economic issues. Some issues have both social and economic aspects, such as immigration. There are also issues that don't fall into either category, such as wars.
Thomas Paine, in Rights of Man and Common Sense, addresses man's duty to "allow the same rights to others as we allow ourselves". The failure to do so causes the birth of a social issue.