Sex

Many species of living things are categorized into two or more forms called sexes that combine genetic material in order to reproduce. This is called sexual reproduction. Typically, a species will have two sexes: male and female (sexual dimorphism). The female is defined as the sex that produces the larger gamete. Fungi and some other organisms exist in more than two sexes, but still reproduce in pairs (any two differing sexes may reproduce). Some species, like earthworms or geckos, are capable of both sexual and asexual reproduction. Some species are hermaphrodites containing both sexes in one body.

The word sex is also used to refer to sexual intercourse (the physical acts related to sexual reproduction) and other human sexual behavior, but this article will discuss the concept of sex defined above.

In mammals, birds, and many other species, sex is determined by the sex chromosomes, called X and Y in mammals, and Z and W in birds. Males typically have one of each (XY), while females typically have two X chromosomes (XX). Since all individuals have at least one X, the Y chromosome is generally reduced, and is absent in some forms, this pattern admitting some considerable variation. In other species, including crocodiles, and most insects, sex may be determined by various other sex-determination systems, including ones controlled by environmental factors like temperature, or by age.

Intersexuals are the small minority of people that were born with bodies that are difficult to assign to the traditional "male" and "female" categories because have both genitalia are of indeterminate sex, or combine features of both sexes. This biological fact has led some scientists to argue that sexes are cultural constructions. Some people have sought to define their sexuality and sexual identity in non-polar terms.

As part of this movement, Anne Fausto-Sterling once suggested a classification of five sexes (male, female, merm, ferm and herm). Advocates for intersexual people stated that this theory is confusing and unhelpful to the interests of intersexual people, and she has since ceased to advocate this idea.

Many social scientists use "sex" to refer to the biological division into male and female, and "gender" to refer to gender roles assigned to people on the basis of sex. There is tremendous variation of cultural attitudes, both between and within societies, to sex, sexuality, and gender roles.

See the article Pictogram for an example of a pictogram of a man and a woman, to indicate the respective toilets. It shows the man with broader shoulders and the woman in clothing that is in the western world rarely worn by men, a dress. Presumably it is not used in countries where men wear dress-like clothing.