Human variability, or human variation, refers to the range of possible values for any measurable characteristic, physical or mental, of human beings. Differences can be trivial or important, transient or permanent, voluntary or involuntary, congenital or acquired, genetic or environmental. This article discusses variabilities that characterize a person for all or much of his or her lifetime, and are perceived as not purely learned or readily changed (such as religion, language, customs, or tastes). Each person being different is so essential a part of human experience that it is difficult to even imagine a human existence in which other people are identical. Furthermore, the social value put on these differences by the society in which one lives affects every aspect of a person's life.

Sources of human variability

• biological inheritance, shaped by
  • mutations, allelic differences
  • genetic drift
  • natural selection
  • prenatal environment and fetal "programming"
  • disease
  • artificial or cultural selection
  • nutrition and malnutrition
  • quality of life and health care
  • pollution and toxin exposure and other stressors
  • education
  • cultural environment
  • social environment
  • family environment and upbringing (especially before age 5)
    • child abuse and neglect
  • accidental or intentional injury, mutilation, or change of the body

While nearly all of the variables listed above are at least partially determined or affected by genetic factors, few of them are controlled by simple Mendelian inheritance. Most are polygenic or are determined by a complex combination of genes and early environment. Essentially, genes provide proclivities and potentialities continuously involving feedback mechanisms with the environment throughout life, but especially during prenatal and early childhood. Biological inheritance is the process by which an offspring cell or organism acquires or becomes predisposed to characteristics of its parent cell or organism. ... It has been suggested that mutant be merged into this article or section. ... For the hard rock band, see Allele (band). ... In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the success of alleles (variants of a gene). ... Darwins illustrations of beak variation in the finches of the Galápagos Islands, which hold 13 closely related species that differ most markedly in the shape of their beaks. ... The term disease refers to an abnormal condition of an organism that impairs function. ... The updated USDA food pyramid, published in 2005, is a general nutrition guide for recommended food consumption. ... Percentage of population affected by malnutrition by country, according to United Nations statistics. ... The well-being or quality of life of a population is an important concern in economics and political science. ... Health care or healthcare is the prevention, treatment, and management of illness and the preservation of mental and physical well-being through the services offered by the medical, nursing, and allied health professions. ... It has been suggested that Pollutant be merged into this article or section. ... The venom of the black widow spider is a potent latrotoxin. ... Culture (from the Latin cultura stemming from colere, meaning to cultivate), generally refers to patterns of human activity and the symbolic structures that give such activity significance. ... The social environment is the direct influence of a group of individuals and their contributions to this environment, as both groups and individuals who are in frequent communication with each other within their cultural or socio-economical strata, which create role identity(-ies) and guide the individuals self (sociology... A family in Ouagadougou, Burkina Faso in 1997 A family consists of a domestic group of people (or a number of domestic groups), typically affiliated by birth or marriage, or by analogous or comparable relationships — including domestic partnership, cohabitation, adoption, surname and (in some cases) ownership (as occurred in the... Child abuse is the physical or psychological maltreatment of a child, often synonymous with the terms child maltreatment and child abuse and neglect. ... It has been suggested that this article or section be merged into Disfigurement. ... Mendelian inheritance (or Mendelian genetics or Mendelism) is a set of primary tenets relating to the transmission of hereditary characteristics from parent organisms to their children; it underlies much of genetics. ... A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ... It has been suggested that this article or section be merged with Feedback loop. ... “Children” redirects here. ...

Many genetic differences (polymorphisms) have little effect on health or reproductive success, but serve to statistically distinguish one population from another. Researchers in the field of population genetics have been using these to elucidate ancient migrations and relationships between population groups. In biology, polymorphism can be defined as the occurrence in the same habitat of two or more forms of a trait in such frequencies that the rarer cannot be maintained by recurrent mutation alone. ... Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ...

Another purely genetic set of individual differences are the blood types and immune types we all carry. While some may carry mild advantages or disadvantages in terms of risks of particular diseases, the primary life-or-death significance comes when we attempt to transfer blood or organs from one person to another. Our immune system is designed to recognize these human differences with great sensitivity and enforce our individuality. Blood type (or blood group) is determined, in part, by the ABO blood group antigens present on red blood cells. ... A scanning electron microscope image of a single neutrophil (yellow), engulfing anthrax bacteria (orange). ...

Social significance and valuation of human variability

Human beings rarely give all possible values for a given parameter the same value, though not all people agree on the values or relative rankings. Examples of differences which may be given different values in different societies include darker/lighter skin color or thinness/fatness. Local valuation may affect social standing, reproductive opportunities, or even survival.

Possession of above average amounts of some abilities is valued by most societies: ability to learn; musical aptitude; strength, endurance, agility; resilience.

Each individual's distinctive differences, even the negatively valued ones, are usually considered an essential part of self-identity. Membership or status in a social group may depend on having specific values for certain attributes. It is not unusual for people to deliberately try to amplify or exaggerate differences, or to conceal or minimize them, for a variety of reasons. Examples of practices designed to minimize differences include hair straightening or skin bleaching, plastic surgery, orthodontia, and growth hormone treatment for extreme shortness. Conversely, male-female differences are enhanced and exaggerated in most societies. “Facial reconstruction” redirects here. ... POOP (or orthodontia) is a specialty of dentistry that is concerned with the study and treatment of malocclusions, which may be a result of tooth irregularity, disproportionate jaw relationships, or both. ... Growth hormone (GH) is a protein hormone secreted by the pituitary gland which stimulates growth and cell reproduction. ...

These differences may vary or be distributed in various ways. Some, like height for a given sex, vary in close to a "normal" or Gaussian distribution. Some characteristics (e.g., skin color) vary continuously in a population, but the continuum may be socially divided into a small number of distinct categories. Some characteristics vary bimodally (sexual orientation, handedness), with fewer people in intermediate categories. The normal distribution, also called Gaussian distribution by scientists (named after Carl Friedrich Gauss due to his rigorous application of the distribution to astronomical data (Havil, 2003)) is a probability distribution of great importance in many fields. ... Sexual orientation refers to the direction of an individuals sexuality, normally conceived of as falling into several significant categories based around the sex or gender that the individual finds attractive. ... Handedness is an attribute of human beings defined by their unequal distribution of fine motor skill between the left and right hands. ...

Different human societies may assign different values to various differences. The obvious examples are race and sex, while handedness has a much weaker value difference, but nearly all human differences will have social value dimension. In some societies, such as the United States, circumcision is practiced on a majority of males, as well as sex reassignment of intersex infants, with substantial emphasis on cultural norms. This article is about male circumcision. ... Sex assignment refers to the assigning of sex at the birth of a baby. ... An intersexual is a person (or individual of any unisexual species) who is born with genitalia and/or secondary sexual characteristics of indeterminate sex, or which combine features of both sexes. ...

Much social controversy surrounds the assigning or distinguishing of some categories, with variation between groups in a society or between societies as to the degree to which a difference is part of a person's "essential" nature or is partly a socially constructed attribution. For example, in the United States and Europe there has been a centuries-long debate over whether sexual orientation is an essential part of one's nature (the "essentialist" position), or a result of mutually reinforcing social perceptions and behavioral choices (the "constructivist" perspective). Other cultures may not even understand the controversy. Nature is innate behavior (behavior not learned or influenced by the environment), character or essence, especially of a human. ...

Controversy also surrounds the boundaries of "wellness", "wholeness," or "normality." In some cultures, physical imperfections can exclude one from religious service. In western culture there has been large-scale renegotiation of the social significance of variations which reduce the ability of a person to do one or more functions. Laws have been passed to alleviate the reduction of social opportunity available to those with disabilities. The concept of "differently abled" has been pushed by those persuading society to see limited incapacities as a human difference of less negative value. Wellness is generally used to mean a healthy balance of the mind-body and spirit that results in an overall feeling of well-being. ... Normal may refer to: Normality in behavior Normal (mathematics) — disambiguation page for mathematics. ... Look up disability in Wiktionary, the free dictionary. ...

When an inherited difference of body structure or function is severe enough, it is termed a genetic disease, but even this classification has fuzzy edges. There are many instances in which the degree of negative value of a human difference depends completely on the social or physical environment. For example, in a society with a large proportion of deaf people (as Martha's Vineyard in the 19th century), it was possible to deny that deafness is a disability. Another example of social renegotiation of the value assigned to a difference is reflected in the controversy over management of ambiguous genitalia, especially whether abnormal genital structure has enough negative consequences to warrant surgical correction. A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ... The word deaf can have very different meanings depending on the background of the person speaking or the context in which the word is used. ... Map of Marthas Vineyard. ... An intersexual is a person (or individual of any unisexual species) who is born with genitalia and/or secondary sexual characteristics of indeterminate sex, or which combine features of both sexes. ...

Furthermore, many genetic traits may be advantageous in certain circumstances and disadvantageous in others. Being a heterozygote or asymptomatic carrier of the sickle-cell disease gene confers some protection against malaria, apparently enough to maintain the gene in populations of malarial areas. In a homozygous dose it is a significant disability. An organism is a heterozygote or heterozygous for a gene or trait if it has different alleles at the genes locus for each homologous chromosome. ... An asymptomatic carrier (or just carrier), is a person who is infected with an infectious disease or carries the abnormal gene of a recessive genetic disorder, but displays no symptoms. ... Sickle-cell disease is a group of genetic disorders caused by sickle hemoglobin (Hgb S or Hb S). ...

The extreme exercise of social valuation of human difference is in the definition of "human." What difference is great enough to assign an individual "nonhuman" status, in the sense of withholding our identification, charity, and social participation? This can change enormously between cultures and over time. For example, nineteenth century European and American ideas of race and eugenics culminated in the attempts of the Nazi-led German society of the 1930s to deny not just reproduction, but life itself to a variety of people with "differences" attributed in part to biologic characteristics. Western society's revulsion to this contributed to a considerable readjustment of valuation of differences. Eugenics is the self-direction of human evolution: Logo from the Second International Congress of Eugenics, 1921, depicting it as a tree which unites a variety of different fields. ... National Socialism redirects here. ...

Contemporary controversy continues over "what kind of human" is a fetus or child with a significant disability. On one end are people who would argue that Down's syndrome is not a disability but a mere "difference," and on the other those who consider such a calamity as to assume that such a child is better off "not born". In India and China, being female is widely considered such a negatively valued human difference that similar decisions are made by the hundreds of thousands. An abortion is the removal or expulsion of an embryo or fetus from the uterus, resulting in or caused by its death. ...

Acknowledgement and study of human differences does have a wide range of uses, such as tailoring the size and shape of manufactured items. See Ergonomics. Ergonomics (or human factors) is the application of scientific information concerning humans to the design of objects, systems and environment for human use. ...

Common human variations

• Sex
  • Male, female, see also intersex
  • those identifying with neither or other than their physical sex, see transgender
  • Sexual orientation, heterosexual, homosexual, bisexual, pansexual, asexual
  • Monogamy, serial monogamy, polygamy, polyamory, "swinging"
• Race
• Body shape and size
  • Height
    • Shortness, dwarfism, Little people
    • Tallness, gigantism
  • Body type/Somatotype, thinness, obesity
• Motor skills, handedness, dexterity
• Physical disabilities
  • Amputation, loss of limbs or limb function
  • Blindness, color blindness
  • Deafness, tone deafness
  • Diseases and defects of other organ systems
• Other aspects of human physical appearance, attractiveness (highly subjective, variable, and impermanent)
  • Skin or eye coloring, complexion
  • Hair color, baldness, hirsutism
  • Supernumerary body part (such as Polydactylism, Supernumerary nipples, Hyperdontia) or missing body parts (such as Hypogenesis)
  • Cleft lip and Cleft palate
• Reproductive attributes and experience
  • Genital modification and mutilation
  • Virginity, fertility, parity, parenthood
• Psychological and personality traits
  • Intelligence, spatial aptitude
  • Temperament, introversion, extroversion, impulsiveness, risk-taking
  • Developmental disability, cognitive disability, social disability
  • Emotional stability, mental illness
• Musical ability

This article or section does not cite its references or sources. ... The shield and spear of the Roman God Mars are often used to represent the male sex In heterogamous species, male is the sex of an organism, or of a part of an organism, which typically produces smaller, mobile gametes (spermatozoa) that are able to fertilise female gametes (ova). ... Look up Female in Wiktionary, the free dictionary. ... An intersexual is a person (or individual of any unisexual species) who is born with genitalia and/or secondary sexual characteristics of indeterminate sex, or which combine features of both sexes. ... Transgender (IPA: , from trans (Latin) and gender (English) ) is a general term applied to a variety of individuals, behaviors, and groups involving tendencies that diverge from the normative gender role (woman or man) commonly, but not always, assigned at birth, as well as the role traditionally held by society. ... Sexual orientation refers to the direction of an individuals sexuality, normally conceived of as falling into several significant categories based around the sex or gender that the individual finds attractive. ... Heterosexuality is a sexual orientation characterized by esthetic attraction, romantic love or sexual desire exclusively for members of the opposite sex or gender, contrasted with homosexuality and distinguished from bisexuality and asexuality. ... Since its coinage, the word homosexuality has acquired multiple meanings. ... This article does not cite its references or sources. ... The adjective pansexual refers to equal acceptance of all of the major human sexual orientations and identities, including heterosexuality, homosexuality, bisexuality, as well as transgender, transsexual and intersex people. ... This article is about human asexuality; asexual reproduction is a separate topic. ... Faithfulness redirects here. ... Serial polygamy is a form of marriage in which participants have more than one sexual partner in their lifetime (hence polygamy), but not at the same time (hence serial). ... The term polygamy (many marriages in late Greek) is used in related ways in social anthropology and sociobiology and sociology. ... Start of polyamory contingent at San Francisco Pride 2004. ... Swinging, sometimes referred to in North America as the swinging lifestyle, is non-monogamous sexual activity, treated much like any other social activity, that can be experienced as a couple. ... The term race describes populations or groups of people distinguished by different sets of characteristics, and beliefs about common ancestry. ... Illustration from The Speaking Portrait (Pearsons Magazine, Vol XI, January to June 1901) demonstrating the principles of Bertillons anthropometry. ... Stature redirects here. ... People who are shorter have short stature. ... see dwarf, and for insular dwarfism and other meanings see Dwarf (disambiguation). ... Little people have been part of the folklore of many cultures in human history, including Ireland, the Philippines, the Hawaiian Islands, Flores Island, Indonesia, and Native Americans. ... Anna Haining Bates with her parents Gigantism or giantism, (from Greek gigas, gigantas giant) is a condition characterized by excessive height growth. ... Body type has several meanings A description of any kind of human body shape: slim, fat, tall, petite, wide-shouldered, pear shaped etcetera. ... The three somatotypes -- endomorphic, mesomorphic, and ectomorphic -- are basic classifications of animal body types according to the prominence of different basic tissues types, roughly: digestive, muscular, and nervous tissues. ... A motor skill is a skill that regards the ability of an organism to utilise skeletal muscles effectively. ... Handedness is an attribute of human beings defined by their unequal distribution of fine motor skill between the left and right hands. ... A little dexterity is helpful in working with knitting needles Look up dexterity in Wiktionary, the free dictionary. ... Disabilities are limitations in activity and/or functioning that are attributable to permanent medical conditions in physical, mental, emotional, and/or sensory domains and, significantly, are also due to societal responses to those limitations. ... Partial hand amputation For the song Amputations by Death Cab for Cutie, see You Can Play These Songs with Chords Amputation is the removal of a body extremity by trauma (also referred to as avulsion) or surgery. ... Blindness is the condition of lacking visual perception due to physiological or psychological factors. ... Color blindness in humans is the inability to perceive differences between some or all colors that other people can distinguish. ... The word deaf can have very different meanings depending on the background of the person speaking or the context in which the word is used. ... The term disease refers to an abnormal condition of an organism that impairs function. ... Variation in the physical appearance of humans is believed by anthropologists to be an important factor in the development of personality and social relations in particular physical attractiveness. ... Physical attractiveness is a measure of an individuals power to attract, arouse interest, or instill pleasure. ... Historical data for native populations collected by R. Biasutti prior to 1940. ... Eye color is a polygenic trait and is determined primarily by the amount and type of pigments present in the eyes iris. ... Complexion describes ones physical appearance. ... This article or section does not adequately cite its references or sources. ... This article or section does not adequately cite its references or sources. ... Hirsutism is defined as excessive and increased hair growth in women in locations where the occurrence of terminal hair normally is minimal or absent. ... An x-ray of a hand with a supernumerary digit (polydactyly). ... Polydactyly, or polydactylism, also known as hyperdactyly is the anatomical variant consisting of more than the usual number of digits on the hands and/or feet. ... Supernumerary nipples. ... In dentistry, hyperdontia is the condition of having supernumerary teeth, teeth which appear in addition to the regular number of teeth. ... Genital modification and genital mutilation both can refer to permanent or temporary changes to the human genitals. ... This article does not cite its references or sources. ... Fertility is a measure of reproduction: the number of children born per couple, person or population. ... A parent is a father or mother; one who begets or one who gives birth to or nurtures and raises a child; a relative who plays the role of guardian // Mother This article or section does not cite its references or sources. ... Psychology is an academic or applied discipline involving the scientific study of mental processes such as perception, cognition, emotion, personality, behavior, and interpersonal relationships. ... In biology, a trait or character is a genetically inherited feature of an organism. ... Intelligence is the mental capacity to reason, plan, solve problems, think abstractly, comprehend ideas and language, and learn. ... In psychology, temperament is the innate aspect of an individuals personality, such as introversion or extroversion. ... The terms Introvert and Extrovert (spelled Extravert by Carl Jung), were originally employed by Sigmund Freud and given significant amplification later by Jung. ... The terms Introvert and Extrovert (originally spelled Extravert by Carl Jung, who invented the terms) are referred to as attitudes and show how a person orients and receives their energy. ... Developmental disability is a term used to describe life-long disabilities attributable to mental and/or physical or combination of mental and physical impairments, manifested prior to age twenty-two. ... This article does not cite its references or sources. ...

See also

• Ableism / disablism
• Adultism
• Ageism
• Auxology
• Anthropometry
• Biphobia
• Body modification
• Classism
• Diversity
• Ergonomics
• Ethnocentrism
• Genetic disease
• Heightism
• Human physical appearance
• Homophobia
• Immunogenetics
• Imprinting
• Individualism
• Intolerance
• Nationalism / Jingoism
• Prejudice
• Population genetics
• Racism
• Religious intolerance
• Sexism
• Transphobia
• Xenophobia

Ableism is a term used to describe discrimination against people with disabilities in favor of people who are able-bodied. ... Disablism is discriminatory, oppressive, or abusive behaviour arising from the belief that people with disabilities are inferior to others. ... Manifestations Slavery · Racial profiling · Lynching Hate speech · Hate crime · Hate groups Genocide · Holocaust · Pogrom Ethnocide · Ethnic cleansing · Race war Religious persecution · Gay bashing Pedophobia · Ephebiphobia Movements Discriminatory Aryanism · Neo-Nazism · Supremacism Kahanism Anti-discriminatory Abolitionism · Civil rights · Gay rights Womens/Universal suffrage · Mens rights Childrens rights · Youth... Manifestations Slavery · Racial profiling · Lynching Hate speech · Hate crime · Hate groups Genocide · Holocaust · Pogrom Ethnocide · Ethnic cleansing · Race war Religious persecution · Gay bashing Pedophobia · Ephebiphobia Movements Discriminatory Aryanism · Neo-Nazism · Supremacism Kahanism Anti-discriminatory Abolitionism · Civil rights Gays/Transsexes/Intersexes rights Womens/Universal suffrage · Feminism Mens/Fathers rights... Auxology is a meta-term covering the study of all aspects of human physical growth; though it is also a fundamental of biology generally. ... Illustration from The Speaking Portrait (Pearsons Magazine, Vol XI, January to June 1901) demonstrating the principles of Bertillons anthropometry. ... Biphobia is the fear of, discrimination against, or hatred of bisexuals (although in practice it extends to pansexual people too). ... This article or section does not cite its references or sources. ... Classism (a term formed by analogy with racism) is any form of prejudice or oppression against people who are in, or who are perceived as being like those who are in, a lower social class (especially in the form of lower or higher socioeconomic status) within a class society. ... Diversity is the presence of a wide range of variation in the qualities or attributes under discussion. ... Ergonomics (or human factors) is the application of scientific information concerning humans to the design of objects, systems and environment for human use. ... Ethnocentrism is the tendency to look at the world primarily from the perspective of ones own culture. ... A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ... Heightism is a form of discrimination based on height. ... Variation in the physical appearance of humans is believed by anthropologists to be an important factor in the development of personality and social relations in particular physical attractiveness. ... Homophobia is the fear of, aversion to, or discrimination against homosexuality or homosexuals. ... Immunogenetics is the branch of medical research that explores the relationship between the immune system and genetics. ... Imprinting has different meanings in: Genetics: see imprinting (genetics) Psychology and ethology: see imprinting (psychology) In addition, the term imprint is used in publishing. ... Individualism is a term used to describe a moral, political, or social outlook that stresses human independence and the importance of individual self-reliance and liberty. ... Intolerance is the lack of ability or willingness to tolerate something. ... Eugène Delacroixs Liberty Leading the People, symbolising French nationalism during the July Revolution. ... Jingoism is a term describing chauvinistic patriotism, usually with a hawkish political stance. ... For with(out) prejudice in law, see Prejudice (law). ... Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ... Manifestations Slavery · Racial profiling · Lynching Hate speech · Hate crime · Hate groups Genocide · Holocaust · Pogrom Ethnocide · Ethnic cleansing · Race war Religious persecution · Gay bashing Pedophobia · Ephebiphobia Movements Discriminatory Aryanism · Neo-Nazism · Supremacism Kahanism Anti-discriminatory Abolitionism · Civil rights Gays/Transsexes/Intersexes rights Womens/Universal suffrage · Feminism Mens/Fathers rights... Religious intolerance is either intolerance motivated by ones own religious beliefs or intolerance against anothers religious beliefs or practices. ... Manifestations Slavery · Racial profiling · Lynching Hate speech · Hate crime · Hate groups Genocide · Holocaust · Pogrom Ethnocide · Ethnic cleansing · Race war Religious persecution · Gay bashing Pedophobia · Ephebiphobia Movements Discriminatory Aryanism · Neo-Nazism · Supremacism Kahanism Anti-discriminatory Abolitionism · Civil rights LGBT rights Womens/Universal suffrage · Feminism Mens/Fathers rights · Masculinism Children... Transphobia refers to various kinds of aversions towards transsexuality and transsexual or transgendered people, often taking the form of refusal to accept a persons expression of their internal gender identity (See Phobia - terms indicating prejudice or class discrimination). ... Look up xenophobia in Wiktionary, the free dictionary. ...

External Links

• Human Variability: A Brief Introduction