Sex
Sex refers to the
male and
female duality of
biology and
reproduction, a process in biological
DNA that dates back 4.6 -
3.5 billion years. DNA links back in an unbroken series of sexual reproduction taking forward information to present day. The somewhat similar term
gender has more to do with
identity than biology. The concept is confined to
organisms that
reproduce sexually.
The female sex is definitely defined as the one which produces the larger
gamete (i.e., reproductive cell) and which typically bears the offspring. The category of
sex reflects the biological reproductive function, rather than sexuality or other behaviors. In some animals, sex may be assigned to specific structures rather than the entire organism as some species, such as
earthworms, are normally
hermaphroditic.
Plants are generally
hermaphrodites, but this terminology is quickly complicated by variations in the degree of sexuality. As with animals, there are only two types of gametes. These are generally called male and female based on their relative sizes and motility. In flowering plants, flowers bear the gametes. In some cases, flowers may contain only one type of gamete, while in others they may contain both.
In other varieties of multicellular life (e.g. the fungi division, Basidiomycota), sexual characteristics can be much more complex, and may involve many more than two sexes. For details on the sexual characteristics of fungi, see:
Hypha and
Plasmogamy.
See Human sexuality for information about sexual activities, sexual sensation, sexual gratification, and sexual intimacy between human beingsIn humans,
sex is conventionally perceived as a dichotomous state or identity for most
biological and
social purposes, such that a person can only be
female or
male. However, when the criteria generally used to define
femaleness and
maleness are examined more closely, it becomes apparent that the assignment or determination of 'sex' occurs at multiple levels. Environmental, biological, social, psychological and other factors are all believed to have some role in this process, and the complex interaction of these factors is expressed in the diversity of biological and psychosocial 'states' or levels found amongst the human population. A significant fraction of the human population simply does not correspond exclusively to either 'female' or 'male' with regard to every level of definition expressed in the following table. This
discordance is discussed in more detail below.
This table outlines the major levels at which society currently recognizes a difference between human females and males. Some criteria are dichotomous and some, such as body size, exhibit
sexual dimorphism (i.e. characteristics which are
statistically more likely to be found in one sex than the other). Some of the levels are more amenable to
scientific study or measurement than others; some are "imputed" or assigned to individuals by the society of which they are members (e.g. whether human males must wear trousers is a result of social
norms); and some seem to be generated within each individual as a subjective identity or drive.
"Primary" sexual characteristics are typically present at birth and directly involved in reproduction.
"Secondary" sexual characteristics typically develop later in life (usually during
puberty) and are not directly involved in reproduction.
| Level of definition | Female | Male | | Biological levels (Sex) |
| Primary sex characteristics (Sex) |
| Usual sex chromosomes | XX in humans | XY in humans |
| Usual gonads | ovaries | testes |
| Usual predominant sex hormones | Estrogen, progesterone | testosterone |
| Usual anatomy of internal genitalia | clitoral crura, vagina, uterus, fallopian tubes | corpora cavernosa, urethra, prostate, seminal vesicles |
| Usual anatomy of external genitalia | glans clitoris, labia, vulva, clitoral hood, perineal urethra | glans penis, scrotum, phallus, foreskin fused perineum |
| Secondary sex characteristics (Sex) |
| Usually | Breasts, menstrual cycle, development of "hourglass" body form (i.e., 8), relatively shorter in height, relatively more body fat | Facial and body hair, development of "triangular" body form (i.e., ▼), relatively taller, relatively less body fat, relatively lower voice |
| Usually both sexes | Pubic hair, underarm hair |
| Psychosocial levels (Gender) |
| Usual Assigned sex | "It's a girl" | "It's a boy" |
| Usual Gender of rearing | "You are a girl" | "You are a boy" |
| Usual Gender identity | "I am a girl/woman" | "I am a boy/man" |
| Usual Gender role | "feminine" social behavior | "masculine" social behavior |
| Usual sexual orientation | androphilic | gynephilic |
The relationship between the various levels of biological sexual differentiation is fairly well understood. Many of the biological levels are said to
cause, or at least shape, the next level. For example, in most people, the presence of a
Y chromosome causes the gonads to become testes, which produce
hormones that cause the internal and external
genitalia to become male, which in turn lead parents to assign 'male' as the sex of their child (
assigned sex), and raise the child as a boy (
gender of rearing). However, the degree to which biological and environmental factors contribute to the psychosocial aspects of sexual differentiation, and even the interrelationships between the various psychosocial aspects of differentiation, is less well understood (see the
nature versus nurture debate).
Discordance
As indicated above, the levels of this
paradigm imply a certain level of 'discordance' amongst the human population, as a result of
diversity amongst humans.
Some discordances are purely biological, such as when the sex of the chromosomes (
genetic sex) does not match the sex of the external genitalia (
anatomic sex). This type of discordance is fairly well understood and is described briefly in the next section, and more fully in the article on
intersex.
Discordances between the biological and psychosocial levels, such as when the
gender identity does not match the anatomic sex, or between the various psychosocial levels, such as when the
gender role does not match the
gender identity, are even more common, but less well understood, generally speaking. These levels of definition and discordance are described below and in individual articles.
Understanding of discordance is important for several reasons. We can learn much about the processes of sexual differentiation, both biological and psychosocial, from people with biological discordances. Some of the levels of discordance have enormous significance to the lives of those affected and their relationships with society. In some cases, the causes of the discordances have acquired controversial political significance. Societies vary on the values placed on some discordances. In the last several decades, the public consensus of many Western societies has come to view some discordances as less undesirable and more tolerable than much of the rest of the world, although this view may exhibit a certain level of
cultural imperialism.
Biological varieties of discordance
Human variability occurs in all the levels by which sex and gender are defined. Discordance at the biological levels is often referred to as an
intersex condition. For example, some women may have an XY
karyotype (chromosomal constellation); these women usually have a condition known as
Complete Androgen Insensitivity Syndrome. Some boys may have a rudimentary
uterus, or an extra X chromosome (
Klinefelter's syndrome). In a small subset of boys and girls with intersex conditions, the external genitalia may be undervirilized or overvirilized. If the degree of
virilization is "in-between", the genitalia are described as "
ambiguous". Many people with intersex conditions do not have ambiguous genitalia. However, for these people, the relationships between biological factors (such as hormones i.e. progesterone, estrogen, and testosterone), environmental factors, and the psychosocial levels of sexual identity, such as
gender identity and
sexual orientation, have proven to be complex, with numerous exceptions to proposed theoretical systems. For example, there have been cases of people with male genetic/chromosomal sex, but with female external
Psychological, behavioral, and cultural varieties of discordance
In contrast to the small percentage of people with biological discordances of sex, a fairly large proportion of human beings may be "discordant" in one or more behavioral or psychological dimensions. The vast majority of these people who are discordant in some aspect of psyche or behavior do not have any detectable biological intersex condition, although some recent studies point towards biological factors in at least some of those conditions. Human societies respond to, or accommodate, these behavioral and psychological discordances in many different ways, ranging from suppression and denial of difference to acknowledging various forms of "third sex".
It may be significant that some societies identify youths with atypical behavioral characteristics and, instead of giving them corrective therapy or punishing them, socialize them in such a way that their individual characteristics let them provide a needed and/or useful function for the society in a recognized and respected role (e.g. individuals who take on the role or customs of
shaman,
medicine man or
tong-ki).
Pictograms of men and women are often used to indicate the respective
toilets designated for each sex. An example of this in the article
pictogram shows the man with broader shoulders (
sex dimorphism) and the woman in
clothing that is, in the western world, rarely worn by men, and which functions as a gender signal. (Presumably these "male human" and "female human" pictograms are not used in countries where men wear dress-like clothing.) In many current societies, it is considered improper for a person of one sex to misrepresent himself or herself as a member of the opposite sex by donning gender-specific clothing of that sex, thereby practicing
transvestism or
cross-dressing. Such behavior receives severe social and/or legal sanctions in some cultures, whilst being tolerated or even celebrated in others.
See also
berdache,
hijra,
xanith and
transgender.
Such complex situations have led some scientists to argue that the two sexes are cultural constructions. Some people have sought to define their sexuality and sexual identity in non-polar terms, in the belief that the simple division of all humans into "males" and "females" does not fit their individual conditions. A proponent of this movement away from polar oppositions,
Anne Fausto-Sterling, once suggested we recognize five sexes: male, female, merm (male
pseudohermaphrodite), ferm (female
pseudohermaphrodite) and herm (
true hermaphrodite). Although this theory was quickly rejected by many as a bizarre flouting of human nature and social reality, inimical to the interests of those whom she was attempting to champion, it expresses the difficulty and imperfection of the current social responses to these variations.
Social and legal considerations
Forms of legal or social distinction or
discrimination based on sex include
sex segregation and
sexism. Notably, some businesses, public institutions, and laws may provide privileges and services for one sex and not another, or they may require different sexes to be physically separated. Recently, western societies have moved towards greater sexual equality.
In
gender theory, the term "
heteronormativity" refers to the idea that human beings fall into two distinct and complementary categories, male and female; that sexual and marital relations are normal only when between two people of different genders; and that each gender has certain natural roles in life.
*
Evolution of sex*
Human sexuality*
List of gender names*
Mammalian gestation*
Sexual differentiation*
Sex ratio*
Were Bacteria the First Forms of Life on Earth having sex?*
Francoeur, Robert T. (ed.),
The International Encyclopedia of Sexuality [full text]
* Janssen, D. F.,
Growing Up Sexually. Volume I. World Reference Atlas [full text]
* Raymond J. Noonan, Robert T. Francoeur, and Martha Cornog,
"Continuum Complete International Encyclopedia of Sexuality". Continuum, August 2003, ISBN 0826414885
*
Human Sexual Differentiation by P. C. Sizonenko
*
New Scientist article on Sex chromosomes in the platypus*
Human Sexuality Info by University of California Santa Barbara
