• Dutch: voortbrengen
• Finnish: synnyttää, saada aikaan, tuottaa

Gender refers to the differences between men and women. Encyclopædia Britannica notes that gender identity is "an individual's self-conception as being male or female, as distinguished from actual biological sex." Although gender is commonly used interchangeably with sex, within the social sciences it often refers to specifically social differences, known as gender roles in the biological sciences. Historically, feminism has posited that many gender roles are socially constructed, and lack a clear biological explanation. People whose gender identity feels incongruent with their physical bodies may call themselves transgender or genderqueer.

Many languages have a system of grammatical gender, a type of noun class system — nouns may be classified as masculine or feminine (for example Spanish, Hebrew, Arabic and French) and may also have a neuter grammatical gender (for example Sanskrit, German, Polish, and the Scandinavian languages). In such languages, this is essentially a convention, which may have little or no connection to the meaning of the words. Likewise, a wide variety of phenomena have characteristics termed gender, by analogy with male and female bodies (such as the gender of connectors and fasteners) or due to societal norms.

Etymology and usage

The word gender in English

As kind

The word gender comes from the Middle English gendre, a loanword from Norman-conquest-era Old French. This, in turn, came from Latin :la:genus. Both words mean 'kind', 'type', or 'sort'. They derive ultimately from a widely attested Proto-Indo-European (PIE) root gen-, which is also the source of kin, kind, king and many other English words. It appears in Modern French in the word genre (type, kind, also :fr:genre sexuel) and is related to the Greek root gen- (to produce), appearing in gene, genesis and oxygen.

As a verb, it means breed in the King James Bible:

• 1616: Thou shalt not let thy cattle gender with a diverse kind — .

Most uses of the root gen in Indo-European languages refer either directly to what pertains to birth or, by extension, to natural, innate qualities and their consequent social distinctions (for example gentry, generation, gentile, genocide and eugenics). The first edition of the Oxford English Dictionary (OED1, Volume 4, 1900) notes the original meaning of gender as 'kind' had already become obsolete.

Gender (dʒe'ndəɹ), sb. Also 4 gendre. [a. OF. gen(d)re (F. genre) = Sp. and Pg. genero, It. genere, ad. L. gener- stem form of genus race, kind = Gr. γένος, Skr. jánas:— OAryan *genes-, f. root γεν- to produce; cf. KIN.]

†1. Kind, sort, class; also, genus as opposed to species. The general gender: the common sort (of people). Obs.

13.. E.E.Allit. P. P. 434 Alle gendrez so ioyst wern ioyned wyth-inne. c 1384 CHAUSER H. Fame* 1. 18 To knowe of hir signifiaunce The gendres. 1398 TREVISA Barth. De P. K. VIII. xxix. (1495) 34I Byshynynge and lyghte ben dyuers as species and gendre, for suery shinyng is lyght, but not ayenwarde. 1602 SHAKES. Ham. IV. vii. 18 The great loue the generall gender beare him. 1604 — Oth. I. iii. 326 Supplie it with one gender of Hearbes, or distract it with many. 1643 and so on.

As masculinity or femininity

The use of gender to refer to masculinity and femininity as types is attested throughout the history of Modern English (from about the 14th century).

• 1387-8: No mo genders been there but masculine, and femynyne, all the remnaunte been no genders but of grace, in facultie of grammar — Thomas Usk, The Testament of Love II iii (Walter William Skeat) 13.
• c. 1460: Has thou oght written there of the femynyn gendere? — Towneley Mystery Plays xxx 161 Act One.
• 1632: Here's a woman! The soul of Hercules has got into her. She has a spirit, is more masculine Than the first gender — Shackerley Marmion, Holland's Leaguer III iv.
• 1658: The Psyche, or soul, of Tiresias is of the masculine gender — Thomas Browne, Hydriotaphia.
• 1709: Of the fair sex ... my only consolation for being of that gender has been the assurance it gave me of never being married to any one among them — Mary Wortley Montagu, Letters to Mrs Wortley lxvi 108.
• 1768: I may add the gender too of the person I am to govern — Laurence Sterne, A Sentimental Journey Through France and Italy.
• 1859: Black divinities of the feminine gender — Charles Dickens, A Tale of Two Cities.
• 1874: It is exactly as if there were a sex in mountains, and their contours and curves and complexions were here all of the feminine gender — Henry James, 'A Chain of Italian Cities', The Atlantic Monthly 33 (February, p. 162.)
• 1892: She was uncertain as to his gender — Robert Grant, 'Reflections of a Married Man', Scribner's Magazine 11 (March, p. 376.)
• 1896: As to one's success in the work one does, surely that is not a question of gender either — Daily News 17 July.
• c. 1900: Our most lively impression is that the sun is there assumed to be of the feminine gender — Henry James, Essays on Literature.

As a grammatical term

According to Aristotle, the Greek philosopher Protagoras used the terms "masculine", "feminine", and "neuter" to classify nouns, introducing the concept of grammatical gender.

The classes (genē) of the nouns are males, females and things.

— Aristotle, The Technique of Rhetoric III v

The words for this concept are not related to gen- in all Indo-European languages (for example, rod in Slavic languages).

The usage of gender in the context of grammatical distinctions is a specific and technical usage. However, in English, the word became attested more widely in the context of grammar, than in making sexual distinctions.

This was noted in OED1, prompting Henry Watson Fowler to recommend this usage as the primary and preferable meaning of gender in English. "Gender ... is a grammatical term only. To talk of persons ... of the masculine or feminine g[ender], meaning of the male or female sex, is either a jocularity (permissible or not according to context) or a blunder."

The sense of this can be felt by analogy with a modern expression like "persons of the female persuasion." It should be noted, however, that this was a recommendation, neither the Daily News nor Henry James citations (above) are "jocular" nor "blunders." Additionally, patterns of usage of gender have substantially changed since Fowler's day (noun class above, and sexual stereotype below).

As a sexual stereotype

The word sex is sometimes used in the context of social roles of men and women — for example, the British Sex Disqualification (Removal) Act 1919 that ended exclusion of women from various official positions. Such usage was more common before the 1970s, over the course of which the feminist movement took the word gender into their own usage to describe their theory of human nature.

Early in that decade, gender was used in ways consistent with both the history of English and the history of attestation of the root.

However, by the end of the decade consensus was achieved among feminists regarding this theory and its terminology. The theory was that human nature is essentially epicene and social distinctions based on sex are arbitrarily constructed. Matters pertaining to this theoretical process of social construction were labelled matters of gender.

• 1998: Today a return to separate single-sex schools may hasten the revival of separate gender roles. — Wendy Kaminer, 'The Trouble with Single-Sex Schools', The Atlantic Monthly (April).

The American Heritage Dictionary uses the following two sentences to illustrate the difference.

• 2000: The effectiveness of the medication appears to depend on the sex (not gender) of the patient.
• 2000: In peasant societies, gender (not sex) roles are likely to be more clearly defined.

In the last two decades of the 20th century, the use of gender in academia increased greatly, outnumbering uses of sex in the social sciences. Frequently, but not exclusively, this indicates acceptance of the feminist theory of human nature. However, in many instances, the term gender still refers to sexual distinction generally without such an assumption.

• 2004: Among the reasons that working scientists have given me for choosing gender rather than sex in biological contexts are desires to signal sympathy with feminist goals, to use a more academic term, or to avoid the connotation of copulation — David Haig, The Inexorable Rise of Gender and the Decline of Sex.

In fact, the ideological distinction between sex and gender is only fitfully observed. More common is the use of modifiers: biologisches Geschlecht for 'biological sex', Geschlechtsidentität for 'gender identity' and Geschlechtsrolle for 'gender role', and so on. Both German and Dutch use a separate word, :de:Genus, for grammatical gender.

Swedish (clear distinction in nouns — genus and kön)

In Swedish, 'gender' is translated with the linguistically cognate :sv:genus, including sociological contexts, thus: Genusstudier (gender studies) and Genusvetenskap (gender science). 'Sex' in Swedish, however, only signifies sexual relations, and not the proposed English dichotomy, a concept for which :sv:kön (also from PIE gen-) is used. A common distinction is then made between kön (sex) and genus (gender), where the former refers only to biological sex. However, Swedish uses the words sv:könsroll and :sv:könsidentitet (literally 'sex role' and 'sex-identity') for the English terms 'gender role' and 'gender identity'.

Summary

The historical meaning of gender is something like "things we treat differently because of their inherent differences". It has three common applications in contemporary English. Most commonly it is applied to the general differences between men and women, without any assumptions regarding biology or sociology. Sometimes however, the usage is technical or assumes a particular theory of human nature, this is always clear from the context. Finally the same word, gender, is also commonly applied to the independent concept of distinctive word categories in certain languages. Grammatical gender has little or nothing to do with differences between men and women.

Likewise, the word sex has two distinct meanings in English. It can be used to describe whether an individual of a sexually reproducing species is physically male or female. Sex in this sense means of or pertaining to reproduction. Used this way, sex, male and female view humans as Homo sapiens and are impersonal, or dehumanizing, in many contexts.

• Person A: We just had our first baby!
• Reply 1: Boy or girl? (personal, suited to a friend)
• Reply 2: Male or female? (impersonal, suited to a doctor — or vet — unsuited to a friend)

The word sex is also used to refer to erotic behaviour between humans, rather more broadly than mating is used of animals. Reproduction is not assumed in reference to human sexual behaviour. Both uses of sex are clearly relevant to the study of differences between men and women.

Biology of gender

The biology of gender became the subject of an expanding number of studies over the course of the late 20th century. One of the earliest areas of interest was what is now called gender identity disorder (GID). Studies in this, and related areas, inform the following summary of the subject by John Money, a pioneer and controversial sex and gender researcher.

Money refers to attempts to distinguish a difference between biological sex and social gender as "scientifically debased", because of our increased knowledge of a continuum of dimorphic features (Money's word is "dipolar"), that link biological and behavioural differences. These extend from the exclusively biological "genetic" and "prenatal hormonal" differences between men and women, to postnatal features, some of which are social, but others have been shown to result from "postpubertal hormonal" effects.

Prior to recent technology that made study of brain differences possible, observable differences in behaviour between men and women could not be adequately explained solely on the basis of the limited observable physical differences between them. Hence the, then plausible, theory that these differences might be explained by arbitrary cultural assignments of roles. However, Money notes concisely that masculine or feminine self-identity is now seen as essentially an expression of dimorphic brain structure (Money's word is "coding"). The new discoveries have an additional advantage over the theory of cultural arbitrariness of gender roles, as they help explain the similarities between these roles in widely divergent cultures (see Steven Pinker on Donald Brown's Human Universals, including romantic love, sexual jealousy, and patriarchy).

Although causation from the biological — genetic and hormonal — to the behavioural has been broadly demonstrated and accepted, Money is careful to also note that understanding of the causal chains from biology to behaviour in sex and gender issues is very far from complete. For example, we have not conclusively identified a "gay gene", but nor have we excluded such a possibility.

The following systematic list (gender taxonomy) illustrates the kinds of diversity that have been studied and reported in medical literature. It is placed in roughly chronological order of biological and social development in the human life cycle. The earlier stages are more purely biological and the latter are more dominantly social. Causation is known to operate from chromosome to gonads, and from gonads to hormones. It is also significant from brain structure to gender identity (see Money quote above). Brain structure and processing (biological) that may explain erotic preference (social), however, is an area of ongoing research. Terminology in some areas changes quite rapidly to accommodate the constantly growing knowledge base. One journal, published since 2002, is specifically devoted to Genes, Brains and Behavior. An interactive, animated display of early development is available online.

Gender taxonomy

• chromosomes: 46xx, 46xy, 47xxy (Klinefelter's syndrome), 45xo (Turner's syndrome), 47xyy, 47xxx, 48xxyy, 46xx/xy mosaic, other mosaic, and others
• gonads: testicles, ovaries, one of each (hermaphrodites), ovotestes, or other gonadal dysgenesis
• hormones: androgens including testosterone; estrogens — including estradiol, estriol, estrone; antiandrogens and others
• genitals: primary sexual characteristics, see diagram for the "six class system"
• secondary sexual characteristics: dimorphic physical characteristics, other than primary characteristics (most prominently breasts or their absence)
• brain structure: special kinds of secondary characteristics, due to their influence on psychology and behaviour
• gender identity: psychological identification with either of the two main sexes
• gender role: social conformity with expectations for either of the two main sexes
• erotic preference: gynophilia, androphilia, bisexuality, asexuality and various paraphilias.

Sex

Sexual reproduction

• Sexual differentiation demands the fusion of gametes which are morphologically different. — Cyril Dean Darlington, Recent Advances in Cytology, 1937.

Sexual reproduction is a popular system of producing new individuals within various species. Individuals of sexually reproducing species produce special kinds of cells called gametes, whose function is specifically to fuse with one unlike gamete and hence form a new individual. This fusion of two unlike gametes is called fertilization. By convention, where one type of gamete cell is physically larger than the other, it is associated with female sex. Thus an individual that produces exclusively large gametes (ova in humans) is said to be female, and one that produces exclusively small gametes (spermatozoa in humans) is said to be male. An individual that produces both types of gametes is called hermaphrodite (a name applicable also to people with one testis and one ovary). In some species hermaphrodites can self-fertilize, in others they can achieve fertilization with females, males or both. Some species, like the Japanese Ash, Fraxinus lanuginosa, only have males and hermaphrodites, a rare reproductive system called androdioecy.

What is considered defining of sexual reproduction is the difference between the gametes and the binary nature of fertilization. Multiplicity of gamete types within a species would still be considered a form of sexual reproduction. However, of more than 1.5 million living species, recorded up to about the year 2000, "no third sex cell — and so no third sex — has appeared in multicellular animals." Why sexual reproduction has an exclusively binary gamete system is not yet known. A few rare species that push the boundaries of the definitions are the subject of active research for light they may shed on the mechanisms of the evolution of sex. For example, the most toxic insect, the harvester ant Pogonomyrmex, has two kinds of female and two kinds of male. One hypothesis is that the species is a hybrid, evolved from two closely related preceding species.

Fossil records indicate that sexual reproduction has been occurring for at least one billion years. However, the reason for the initial evolution of sex, and the reason it has survived to the present are still matters of debate, there are many plausible theories. It appears that the ability to reproduce sexually has evolved independently in various species on many occasions. There are cases where it has also been lost. The flatworm, Dugesia tigrina, and a few other species can reproduce either sexually or asexually depending on various conditions.

Sexual differentiation

Although sexual reproduction is defined at the cellular level, key features of sexual reproduction operate within the structures of the gamete cells themselves. Notably, gametes carry very long molecules called DNA that the biological processes of reproduction can "read" like a book of instructions. In fact, there are typically many of these "books", called chromosomes. Human gametes usually have 23 chromosomes, 22 of which are common to both sexes. The final chromosomes in the two human gametes are called sex chromosomes because of their role in sex determination. Ova always have the same sex chromosome, labelled X. About half of spermatozoa also have this same X chromosome, the rest have a Y chromosome. At fertilization the gametes fuse to form a cell, usually with 46 chromosomes, and either XX female or XY male, depending on whether the sperm carried an X or a Y chromosome. Some of the other possibilities are listed above.

In humans, the "default" processes of reproduction result in an individual with female characteristics. An intact Y chromosome contains what is needed to "reprogram" the processes sufficiently to produce male characteristics, leading to sexual differentiation (see also Sexual dimorphism). Part of the Y chromosome, the Sex-determining Region Y (SRY), causes what would normally become ovaries to become testes. These, in turn, produce male hormones called androgens. However, several points in the processes have been identified where variations can result in people with atypical characteristics, including atypical sexual characteristics. Terminology for atypical sexual characteristics has not stabilized. Disorder of sexual development (DSD) is used by some in preference to intersex, which is used by others in preference to pseudohermaphroditism.

Androgen insensitivity syndrome (AIS) is an example of a DSD that also illustrates that female development is the default for humans. Although having one X and one Y chromosome, some people are biologically insensitive to the androgens produced by their testes. As a result they follow the normal human processes which result in a person of female sex. Women who are XY report identifying as a woman — feeling and thinking like a woman — and, where their biology is completely insensitive to masculinizing factors, externally they look identical to other women. Unlike other women, however, they cannot produce ova, because they do not have ovaries.

The human XY system is not the only sex determination system. Birds typically have a reverse, ZW system — males are ZZ and females ZW. Whether male or female birds influence the sex of offspring is not known for all species. Several species of butterfly are known to have female parent sex determination. The platypus has a complex hybrid system, the male has ten sex chromosomes, half X and half Y.

Genes, Brains and Behaviour

Genes

Chromosomes were likened to books (above), also like books they have been studied at more detailed levels. They contain "sentences" called genes. In fact, many of these sentences are common to multiple species. Sometimes they are organized in the same order, other times they have been "edited" — deleted, copied, changed, moved, even relocated to another "book", as species evolve. Genes are a particularly important part of understanding biological processes because they are directly associated with observable objects, outside chromosomes, called proteins, whose influence on cell chemistry can be measured. In some cases genes can also be directly associated with differences clear to the naked eye, like eye-colour itself. Some of these differences are sex specific, like hairy ears. The "hairy ear" gene is on the Y chromosome which is why only men have it. However, sex-limited genes on any chromosome can "say" for example, "if you are in a male body do X, otherwise don't." The same principle explains why chimpanzees and humans are distinct, despite sharing nearly all their genes.

The study of genetics is particularly inter-disciplinary. It is relevant to almost every biological science. It is investigated in detail by molecular level sciences, and itself contributes details to high level abstractions like evolutionary theory.

Brain

"It is well established that men have a larger cerebrum than women by about 8–10% (Filipek et al., 1994; Nopoulos et al., 2000; Passe et al., 1997a,b; Rabinowicz et al., 1999; Witelson et al., 1995). However, what is functionally relevant are differences in composition and "wiring", some of these differences are very pronounced. Richard J. Haier and colleagues at the universities of New Mexico and California (Irvine) found, using brain mapping, that men have more than six times the amount of grey matter related to general intelligence than women, and women have nearly ten times the amount of white matter related to intelligence than men.

Gray matter is used for information processing, while white matter consists of the connections between processing centers. Other differences are measurable but less pronounced. Most of these differences are known to be produced by the activity of hormones, hence ultimately derived from the Y chromosome and sexual differentiation. However, differences arising from the activity of genes directly have also been observed. It has also been demonstrated that brain processing responds to the external environment. Learning, both of ideas and behaviours, appears to be coded in brain processes. It also appears that in several simplified cases this coding operates differently, but in some ways equivalently, in the brains of men and women. For example, both men and women learn and use language; however, bio-chemically, they appear to process it differently. Differences in male and female use of language are likely reflections both of biological preferences and aptitudes, and of learned patterns.

Two of the main fields that study brain structure, biological (and other causes) and behavioural (and other results) are brain neurology and biological psychology. Cognitive science is another important discipline in the field of brain research.

Behaviour

Some behaviours are so simple that biological explanation may be sufficient. Blinking, yawning and stretching are more reflexes than behaviours. However, etiquette and protocol are complicated behaviours, presumably influenced by many environmental factors, including social (man-made) ones. A large area of research in behavioural psychology collates evidence in an effort to discover correlations between behaviour and various possible antecedents such as genetics, culture, gender, physical or social development, or physical or social environments.

A core research area within sociology is the way human behaviour operates on itself, in other words, how the behaviour of one group or individual influences the behaviour of other groups or individuals. Starting in the late 20th century, the feminist movement has contributed extensive study of gender and theories about it, notably within sociology but not restricted to it.

Social categories

Sociology

Sexologist John Money coined the term gender role in 1955. "The term gender role is used to signify all those things that a person says or does to disclose himself or herself as having the status of boy or man, girl or woman, respectively. It includes, but is not restricted to, sexuality in the sense of eroticism." Elements of such a role include clothing, speech patterns, movement, occupations and other factors not limited to biological sex. Because social aspects of gender can normally be presumed to be the ones of interest in sociology and closely related disciplines, gender role is often abbreviated to gender in their literature, without leading to ambiguity in that context.

Most societies have only two distinct, broad classes of gender roles — male and female — and these correspond with biological sex. However, some societies explicitly incorporate people who adopt the gender role opposite to their biological sex, for example the Two-Spirit people of some indigenous American peoples. Other societies include well-developed roles that are explicitly considered more or less distinct from archetypal male and female roles in those societies. In the language of the sociology of gender they comprise a third gender, more or less distinct from biological sex (sometimes the basis for the role does include intersexuality or incorporates eunuchs). One such gender role is that adopted by the hijras of India and Pakistan. The Bugis people of Sulawesi, Indonesia have a tradition incorporating all of the features above. Joan Roughgarden argues that in some non-human animal species, there can also be said to be more than two genders, in that there might be multiple templates for behavior available to individual organisms with a given biological sex.

Throughout history social theorists have sought to determine the specific nature of gender in relation to biological sex and sexuality, with the result being that culturally established gender and sex have become interchangeable identifications which signify the allocation of a specific ‘biological’ sex within a categorical gender.