Collection of sex toys

Vending machine selling a range of sex toys

A sex toy is an object or device that is primarily used to facilitate human sexual pleasure. Many popular sex toys are designed to resemble human genitals and may be vibrating or non-vibrating. The term can also include BDSM apparatus and sex furniture such as slings, however it is not applied to items such as birth control, pornography, or condoms.

Alternative expressions include adult toy and marital aid, although "marital aid" has a broader sense and is applied to drugs and herbs marketed to supposedly enhance or prolong sex.

Types of sex toys[link]

Vibrators[link]

Jigsaw Squirting

Vibrators are vibrating devices intended to stimulate the body. Vibrators come in a range of shapes and sizes, for internal or external use. Some vibrators intended for internal use are phallic in shape. Small vibrators may have a stretchy loop attachment for use as a finger toy or cock ring.

• Penetrative vibrators usually measure twelve to eighteen cm (five to seven inches) in length and two to five cm (one to two inches) wide often to mimic the size of the average penis.^[1]
• Anal vibrators are designed to be inserted into the rectum, which may stimulate the prostate in men. The safest ones have a flared base which remains outside the body, that prevents the toy from becoming irretrievable.
• G-spot vibrators are curved at one end to facilitate stimulation of the female G-spot.
• Bullet vibrators are small, bullet-shaped vibrators that can be used for direct stimulation or inserted into other sex toys to increase stimulation. Some are sold with stretchy loops for attachment as a finger toy or cock ring.
• Vibrator wands, such as the Hitachi Magic Wand, are large vibrators that generally plug into an electrical outlet (versus operating on battery power) and are often marketed as back massagers. They are able to produce far more powerful vibration than most battery-powered vibrators. Various attachments made of silicone or a rubber material allow the toy to be used penetratively, or give the toy more interesting texture.
• The rabbit vibrator, of which there are several variations, is a popular female sex toy popularized by the television series Sex and the City.^[2] It comprises an insertable shaft which often has additional functionality, such as rotation and internal beads or a thrusting action. Attached to the shaft is a vibrating clitoral stimulator. For most rabbit vibrators this comes in the form of "bunny ears" which sit each side of the clitoris.
• Luxury vibrators have an increased focus on design and the use of expensive materials that appeal to a more upscale fashion market.

Penile toys[link]

A penis sleeve

• "Artificial vaginas", also known as "pocket pussies" or "masturbators", are modelled to accept a penis for simulated intercourse. They can be shaped like vaginas, anuses, or anything with a hole for penetration. Some are equipped with sex-machine options that work similar to milking machines.^[3]
• A fifi (also fifi towel or fifi bag) is a slang term for an improvised vagina, often made of cloth or fabric.^[4][5]
• Cock rings prolong male erection by holding blood inside the penis. A man may wear a cock-ring to combat erectile difficulties, or for the sensation of tightness and engorgement that wearing one provides. Some models include a protruding clitoral stimulator, designed to stimulate the clitoris during sex. Others vibrate, either vibrating the ring itself, or in a popular 'Dolphin' variant by using two removable bullet vibrators to provide stimulation to both the testicles and clitoris. Some cock rings also have vibrators attached which can be worn to stimulate a partner during sexual intercourse, especially in the scrotum or perineum.
• A triple crown is a special cock-ring that has additional rings for restraining the testicles. In orgasm, the testicles usually retract toward the body before ejaculation. A triple crown changes and intensifies the sensation of orgasm by forcing the testicles to stay away from the body.
• A cock harness is a more elaborate harness designed to be worn around the penis and scrotum. Its function is similar to that of a cock ring. These devices are often associated with BDSM activities such as cock and ball torture. An Arab strap is one such form of harness, purported to be a device used for maintaining an erection.
• A ball lock is an ordinary padlock fastened around the male scrotum, separating the testicles away from the penis and not removable except by key or combination.
• A penis sleeve is a cylindrical device that is placed on the shaft of the penis, with the aim of increasing stimulation for the person being penetrated. They often have soft bumps intended to provide further stimulation.

A glass dildo

• A penis extension is a partially hollow device like a very short dildo, with the hollow end placed on the end of the penis, intended to increase the effective length of the penis, again for the benefit of the person being penetrated. These are generally worn with condoms to prevent them from falling off during use.
• A docking sleeve is a cylindrical device similar to a penis sleeve, but is open at both ends, so that two men can dock, a form of mutual masturbation.

Glass sex toys[link]

Glass sex toys are commonly made from clear medical grade borosilicate glass ("hard glass"), which is non-toxic and will withstand extreme temperatures as well as physical shock without compromising its structural integrity. The choice of this material provides safety in use and the option to heat or chill the toys. It is also non-porous and can be sterilized to help prevent infection with reuse. Apart from their practical qualities, a main selling point of glass sex toys is their visual appeal.

Nipple toys[link]

Anal beads in practice

• A nipple clamp is a clamp used to stimulate the nipples by applying varying degrees of pressure.
• Suction devices are generally either rubber or glass, fit around the nipple, and cause nipples to become more sensitive due to engorgement. Glass suction devices may use either heat or a pump to create suction.

Anal toys[link]

• Butt plugs are often shorter dildos intended for anal insertion. They tend to have a flared base to prevent the device from becoming lodged in the rectum.

Two butt plugs

Butt plugs should not be shared with other people, due to the risk of blood-borne diseases, including HIV that can arise from the transfer of body fluids from one person to another. They should be used only for anal play and not inserted into any other orifice, to avoid the transfer of harmful bacteria to other parts of the body. These bacteria may persist through cleaning.

• Prostate massagers are devices designed to stimulate a man's prostate for health and pleasure.
• Anal beads

General penetrative toys[link]

• A dildo is a non-vibrating device which is used for sexual stimulation of the vagina and/or anus. Dildos are generally made of silicone rubber, but can be made of other materials such as metals or glass. They are often made to resemble a penis.
• A double penetration dildo is a long, usually flexible dildo with both ends designed for penetration. It allows for mutual penetration between two persons (or for double penetration of a single female, both anally and vaginally).
• Ben Wa balls are hollow metal balls inserted vaginally which can be worn inside the vagina for extended periods of time. The internal rolling is claimed to enhance orgasms.

A type of Ben-Wa balls

• Kegel exerciser, also known as vaginal barbells or jugglers are designed to improve muscle tone in the pelvic floor, and can be used for sexual pleasure as well as enhancing vaginal response.
• A horseshoe is a non-vibrating sex toy which is shaped similar to a horseshoe, which is put into the vagina and anus at the same time. It is made with softer plastics.
• A sex-machine is a motor-driven device that combines penetration with rotational and/or reciprocal movement.^[6]

Erotic furniture[link]

Erotic furniture is furniture specially shaped for comfort, penetration levels, and stimulation.

Improvised Sex Toys[link]

A significant interest has grown up in improvised sex toys and object penetration. Items used include fruit, vegetables, bottles, vases, and baseball bats.

Flesh-like materials used in sex toys[link]

• Silicone is soft and lifelike, it is hypoallergenic, warms up quickly to body temperature, non-porous and so is easy to clean (with mild soap and water, or boiled for sterilization). Unlike jelly rubber and other porous materials, silicone can be sterilized in temperatures up to 300 °C (572 °F). In addition, it can be bleached in a 10% bleach solution. When using lubricants with silicone sex toys it is important that silicone or silicone-based lubricants are not used to avoid damage to the toy.
• CyberSkin is a thermal plastic elastomer and is a close emulation of real skin. CyberSkin is made from ingredients on FDA approved lists and it does not contain phthalates, polyvinyl chloride (PVC), heavy metals or latex. It is easy to clean and maintain by washing it with soap and water, patting dry. Water based lubricants are best and they should be stored in a dry place.

• Latex rubber, also called jelly rubber, is commonly used for sex toys; it is a flexible and inexpensive material allowing the user more options in size and look. While latex is commonly used and less expensive than materials such as silicone, glass and CyberSkin, it can be allergenic to some people with latex allergy. Latex is porous and should be cleaned thoroughly with an antibacterial soap and water and not shared with other people. Some rubber toys contain phthalates which are used to soften rubber, but carry serious risks. Studies have been done that showed adverse reproductive effects in animal and human subjects. Further research is ongoing but phthalates have a known detrimental effect on multiple facets of human health and their use in sex toys is strongly discouraged. It is recommended by many experts that one use a condom with each use for protection against bacterial infection or sexually transmitted diseases if one is sharing sex toys. Water and silicone-based lubricants can be used with latex toys, but oil-based lubricants and petroleum jelly should not be used with latex as these may adversely affect the toy.

Health and safety concerns[link]

Danish retailers report that they often lack information about the composition of sex toys that they sell.^[7] A recent (2006) study conducted by the Greenpeace Netherlands office found high level of phthalates in seven out of eight plastic sex toys tested.^[8]

Studies on rodents have revealed that when exposed to very large doses, phthalates can cause damage to the liver, lungs, kidneys, testes and can cause hormonal disruption. The latest research indicates that exposure to these substances can upset the body's ability to regulate hormone production, damage reproduction, and can cause liver and kidney defects. They can also possibly cause cancer.^[9]

Sex toys are currently classified as novelties, despite their sexual nature. This is because sex toy manufacturers find the FDA (Food and Drug Administration) to have extensive testing and financial requirements for sex toys to be classified as medical devices. Therefore, sex toy manufacturers more often choose the less complex production by labelling them a novelty. Due to the novelty classification, sex toys are permitted to contain known toxins in them such as Phthalates (some of which have been banned in children’s toys by the CPSC) and in some cases lead paint.

In 2000, the development toward safe and nontoxic sex toys in the United States began with sexual health pioneers such as Lisa S. Lawless, Ph.D. who founded one of the first retail sex toy stores (Holistic Wisdom) to carry only nontoxic sex toys. Her articles, radio and magazine interviews have been a major influence in the public eye; allowing consumers to become more aware of health concerns regarding sex toy safety. Lawless also began a movement toward safer sex toys through the National Association for the Advancement of Science & Art in Sexuality (NAASAS). This trade organization works with professionals in the field of sexuality and the adult industry to self regulate the safety of sex toys.

Legal issues[link]

The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. Please improve this article and discuss the issue on the talk page. (September 2010)

Several countries have enacted laws to ban or curb the use of sex toys.

United States[link]

Sex toys and lubricants have become increasingly available in major commercial outlets in the United States. On-shelf displays tend to be more discreet than the offerings on web sites. These items tend to be displayed in the "sexual health" sections of stores.^[10]

Until recently, many Southern and some Great Plains states banned the sale of sex toys completely, either directly or through laws regulating "obscene devices."^[11] In 1999, William H. Pryor, Jr., an assistant attorney general in Alabama commenting on a case involving sex toys and discussing to what end the devices are used, was quoted as saying there is no "fundamental right for a person to buy a device to produce orgasm". A federal appeals court upheld Alabama's law prohibiting the sale of sex toys on Valentine's Day, 2007.^[12]

In February 2008, a federal appeals court overturned a Texas statute banning the sales of sex toys, deeming such a statute as violating the Constitution's 14th Amendment on the right to privacy.^[13] The appeals court cited Lawrence v. Texas, where the U.S. Supreme Court in 2003 struck down bans on consensual sex between gay couples, as unconstitutionally aiming at "enforcing a public moral code by restricting private intimate conduct." Similar statutes have been struck down in Kansas and Colorado.

India[link]

Sex toys are illegal in India^[14] Selling sex toys is a punishable offense under section 292 of Indian penal code, with up to two years in prison.^[15] Pornography in India is not punishable

South Africa[link]

Section 18A of the Sexual Offences Act, 1957, inserted by the Immorality Amendment Act, 1969, prohibited the manufacture or sale of any item "intended to be used to perform an unnatural sexual act". The term "unnatural sexual act" referred to any sex other than vaginal heterosexual sex, and this prohibition was ostensibly aimed at preventing the use of dildos by lesbians.^[16] No longer enforced, the section was repealed by the Criminal Law (Sexual Offences and Related Matters) Amendment Act, 2007.

Ethical issues[link]

Some Conservative Christians believe that the use of sex toys is immoral and prohibited by the Bible.^{[says who?]} An American Baptist preacher, Dan Ireland, has been an outspoken critic of such devices and has fought to ban them on religious and ethical grounds. According to Ireland, "Sometimes you have to protect the public against themselves....These devices should be outlawed because they are conducive to promiscuity, because they promote loose morals and because they entice improper and potentially deadly behaviors."^[17] Ireland believes that "there is no moral way to use one of these devices."^[17]

Dr. Marty Klein, author of America's War on Sex and an advocate for the moral value of sex toys, has written of sex toy bans that this "extraordinary erosion of personal liberty, coupled with the massive disrespect of and fear of sexuality is no joke" and that the "Supreme Court [of the United States] has declared our orgasms a battlefield, and sex toys another casualty."^[18]

Industry[link]

Globally, the sex toy industry is valued at USD 15 billion, with a growth rate of 30%.^[19] 70% of sex toys are manufactured in China.^[19]

See also[link]

• Anti-Obscenity Enforcement Act
• BDSM
• Erotic furniture
• Fleshlight
• Genital jewellery
• Masturbation aids
• Sex doll
• Sex Machines
• Sex Machines Museum
• Sex toy party
• Sybian
• Venus 2000
• Teledildonics
• Tenga (masturbation toy)

References[link]

Further reading[link]

• Timothy Archibald. Sex Machines: Photographs and Interviews. Process, 2005. ISBN 0-9760822-3-3.
• Karlyn Lotney. The Ultimate Guide to Strap-On Sex: A Complete Resource for Women and Men Cleis Press, 2000. ISBN 1-57344-085-X.

External links[link]

Wikimedia Commons has media related to: Sex toys

• BBC page about c1700s sex toys sold at auction
• Homemade sex toys

The male gamete (sperm) fertilizing the female gamete (egg cell)

In biology, sexual reproduction is a process of combining and mixing genetic traits, often resulting in the specialization of organisms into a male or female variety, each known as a sex. Sexual reproduction involves combining specialized cells (gametes) to form offspring that inherit traits from both parents. Gametes can be identical in form and function (known as isogametes), but in many cases an asymmetry has evolved such that two sex-specific types of gametes (heterogametes) exist: male gametes are small, motile, and optimized to transport their genetic information over a distance, while female gametes are large, non-motile and contain the nutrients necessary for the early development of the young organism.

An organism's sex is defined by the gametes it produces: males produce male gametes (spermatozoa, or sperm) while females produce female gametes (ova, or egg cells); individual organisms which produce both male and female gametes are termed hermaphroditic. Frequently, physical differences are associated with the different sexes of an organism; these sexual dimorphisms can reflect the different reproductive pressures the sexes experience.

Evolution[link]

It is considered that sexual reproduction first appeared about a billion years ago, evolved within ancestral single-celled eukaryotes.^[1] The reason for the initial evolution of sex, and the reason(s) it has survived to the present, are still matters of debate. Some of the many plausible theories include: that sex creates variation among offspring, sex helps in the spread of advantageous traits, and that sex helps in the removal of disadvantageous traits.

Sexual reproduction is a process specific to eukaryotes, organisms whose cells contain a nucleus and mitochondria. In addition to animals, plants, and fungi, other eukaryotes (e.g. the malaria parasite) also engage in sexual reproduction. Some bacteria use conjugation to transfer genetic material between cells; while not the same as sexual reproduction, this also results in the mixture of genetic traits.

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, no third gamete is known in multicellular animals.^[2][3][4]

While the evolution of sex itself dates to the eukaryote stage, the origin of chromosomal sex determination is younger. The ZW sex-determination system is shared by birds, some fish and some crustaceans. Most mammals, but also some insects (Drosophila) and plants (Ginkgo) use XY sex-determination. X0 sex-determination is found in certain insects.

No genes are shared between the avian ZW and mammal XY chromosomes,^[5] and from a comparison between chicken and human, the Z chromosome appeared similar to the autosomal chromosome 9 in human, rather than X or Y, suggesting that the ZW and XY sex-determination systems do not share an origin, but that the sex chromosomes are derived from autosomal chromosomes of the common ancestor of birds and mammals. A paper from 2004 compared the chicken Z chromosome with platypus X chromosomes and suggested that the two systems are related.^[6]

Sexual reproduction[link]

The life cycle of sexually reproducing organisms cycles through haploid and diploid stages.

Sexual reproduction is a process where organisms form offspring that combine genetic traits from both parents. Chromosomes are passed on from one generation to the next in this process. Each cell in the offspring has half the chromosomes of the mother and half of the father.^[7] Genetic traits are contained within the deoxyribonucleic acid (DNA) of chromosomes – by combining one of each type of chromosomes from each parent, an organism is formed containing a doubled set of chromosomes. This double-chromosome stage is called "diploid", while the single-chromosome stage is "haploid". Diploid organisms can, in turn, form haploid cells (gametes) that randomly contain one of each of the chromosome pairs, via a process called meiosis.^[8] Meiosis also involves a stage of chromosomal crossover, in which regions of DNA are exchanged between matched types of chromosomes, to form a new pair of mixed chromosomes. Crossing over and fertilization (the recombining of single sets of chromosomes to make a new diploid) result in the new organism containing a different set of genetic traits from either parent.

In many organisms, the haploid stage has been reduced to just gametes specialized to recombine and form a new diploid organism; in others, the gametes are capable of undergoing cell division to produce multicellular haploid organisms. In either case, gametes may be externally similar, particularly in size (isogamy), or may have evolved an asymmetry such that the gametes are different in size and other aspects (anisogamy).^[9] By convention, the larger gamete (called an ovum, or egg cell) is considered female, while the smaller gamete (called a spermatozoon, or sperm cell) is considered male. An individual that produces exclusively large gametes is female, and one that produces exclusively small gametes is male. An individual that produces both types of gametes is a hermaphrodite; in some cases hermaphrodites are able to self-fertilize and produce offspring on their own, without a second organism.^[10]

Animals[link]

Hoverflies engaging in sexual intercourse

Most sexually reproducing animals spend their lives as diploid organisms, with the haploid stage reduced to single cell gametes.^[11] The gametes of animals have male and female forms—spermatozoa and egg cells. These gametes combine to form embryos which develop into a new organism.

The male gamete, a spermatozoon (produced within a testicle), is a small cell containing a single long flagellum which propels it.^[12] Spermatozoa are extremely reduced cells, lacking many cellular components that would be necessary for embryonic development. They are specialized for motility, seeking out an egg cell and fusing with it in a process called fertilization.

Female gametes are egg cells (produced within ovaries), large immobile cells that contain the nutrients and cellular components necessary for a developing embryo.^[13] Egg cells are often associated with other cells which support the development of the embryo, forming an egg. In mammals, the fertilized embryo instead develops within the female, receiving nutrition directly from its mother.

Animals are usually mobile and seek out a partner of the opposite sex for mating. Animals which live in the water can mate using external fertilization, where the eggs and sperm are released into and combine within the surrounding water.^[14] Most animals that live outside of water, however, must transfer sperm from male to female to achieve internal fertilization.

In most birds, both excretion and reproduction is done through a single posterior opening, called the cloaca—male and female birds touch cloaca to transfer sperm, a process called "cloacal kissing".^[15] In many other terrestrial animals, males use specialized sex organs to assist the transport of sperm—these male sex organs are called intromittent organs. In humans and other mammals this male organ is the penis, which enters the female reproductive tract (called the vagina) to achieve insemination—a process called sexual intercourse. The penis contains a tube through which semen (a fluid containing sperm) travels. In female mammals the vagina connects with the uterus, an organ which directly supports the development of a fertilized embryo within (a process called gestation).

Because of their motility, animal sexual behavior can involve coercive sex. Traumatic insemination, for example, is used by some insect species to inseminate females through a wound in the abdominal cavity – a process detrimental to the female's health.

Plants[link]

Flowers are the sexual organs of flowering plants, usually containing both male and female parts.

Like animals, plants have developed specialized male and female gametes.^[16] Within most familiar plants, male gametes are contained within hard coats, forming pollen. The female gametes of plants are contained within ovules; once fertilized by pollen these form seeds which, like eggs, contain the nutrients necessary for the development of the embryonic plant.

Female (left) and male (right) cones are the sex organs of pines and other conifers.

Many plants have flowers and these are the sexual organs of those plants. Flowers are usually hermaphroditic, producing both male and female gametes. The female parts, in the center of a flower, are the carpels—one or more of these may be merged to form a single pistil. Within carpels are ovules which develop into seeds after fertilization. The male parts of the flower are the stamens: these long filamentous organs are arranged between the pistil and the petals and produce pollen at their tips. When a pollen grain lands upon the top of a carpel, the tissues of the plant react to transport the grain down into the carpel to merge with an ovule, eventually forming seeds.

In pines and other conifers the sex organs are conifer cones and have male and female forms. The more familiar female cones are typically more durable, containing ovules within them. Male cones are smaller and produce pollen which is transported by wind to land in female cones. As with flowers, seeds form within the female cone after pollination.

Because plants are immobile, they depend upon passive methods for transporting pollen grains to other plants. Many plants, including conifers and grasses, produce lightweight pollen which is carried by wind to neighboring plants. Other plants have heavier, sticky pollen that is specialized for transportation by insects. The plants attract these insects with nectar-containing flowers. Insects transport the pollen as they move to other flowers, which also contain female reproductive organs, resulting in pollination.

Fungi[link]

Mushrooms are produced as part of fungal sexual reproduction

Most fungi reproduce sexually, having both a haploid and diploid stage in their life cycles. These fungi are typically isogamous, lacking male and female specialization: haploid fungi grow into contact with each other and then fuse their cells. In some of these cases the fusion is asymmetric, and the cell which donates only a nucleus (and not accompanying cellular material) could arguably be considered "male".^[17]

Some fungi, including baker's yeast, have mating types that create a duality similar to male and female roles. Yeast with the same mating type will not fuse with each other to form diploid cells, only with yeast carrying the other mating type.^[18]

Fungi produce mushrooms as part of their sexual reproduction. Within the mushroom diploid cells are formed, later dividing into haploid spores—the height of the mushroom aids the dispersal of these sexually produced offspring.

Sex helps the spread of advantageous traits through recombination. The diagrams compare evolution of allele frequency in a sexual population (top) and an asexual population (bottom). The vertical axis shows frequency and the horizontal axis shows time. The alleles a/A and b/B occur at random. The advantageous alleles A and B, arising independently, can be rapidly combined by sexual reproduction into the most advantageous combination AB. Asexual reproduction takes longer to achieve this combination, because it can only produce AB if A arises in an individual which already has B, or vice versa.

Sex determination[link]

The most basic sexual system is one in which all organisms are hermaphrodites, producing both male and female gametes—this is true of some animals (e.g. snails) and the majority of flowering plants.^[19] In many cases, however, specialization of sex has evolved such that some organisms produce only male or only female gametes. The biological cause for an organism developing into one sex or the other is called sex determination.

In the majority of species with sex specialization, organisms are either male (producing only male gametes) or female (producing only female gametes). Exceptions are common—for example, in the roundworm C. elegans the two sexes are hermaphrodite and male (a system called androdioecy).

Sometimes an organism's development is intermediate between male and female, a condition called intersex. Sometimes intersex individuals are called "hermaphrodite"; but, unlike biological hermaphrodites, intersex individuals are unusual cases and are not typically fertile in both male and female aspects.

Genetic[link]

Like humans and other mammals, the common fruit fly has an XY sex-determination system.

In genetic sex-determination systems, an organism's sex is determined by the genome it inherits. Genetic sex-determination usually depends on asymmetrically inherited sex chromosomes which carry genetic features that influence development; sex may be determined either by the presence of a sex chromosome or by how many the organism has. Genetic sex-determination, because it is determined by chromosome assortment, usually results in a 1:1 ratio of male and female offspring.

Humans and other mammals have an XY sex-determination system: the Y chromosome carries factors responsible for triggering male development. The default sex, in the absence of a Y chromosome, is female. Thus, XX mammals are female and XY are male. XY sex determination is found in other organisms, including the common fruit fly and some plants.^[19] In some cases, including in the fruit fly, it is the number of X chromosomes that determines sex rather than the presence of a Y chromosome (see below).

In birds, which have a ZW sex-determination system, the opposite is true: the W chromosome carries factors responsible for female development, and default development is male.^[20] In this case ZZ individuals are male and ZW are female. The majority of butterflies and moths also have a ZW sex-determination system. In both XY and ZW sex determination systems, the sex chromosome carrying the critical factors is often significantly smaller, carrying little more than the genes necessary for triggering the development of a given sex.^[21]

Many insects use a sex determination system based on the number of sex chromosomes. This is called X0 sex-determination—the 0 indicates the absence of the sex chromosome. All other chromosomes in these organisms are diploid, but organisms may inherit one or two X chromosomes. In field crickets, for example, insects with a single X chromosome develop as male, while those with two develop as female.^[22] In the nematode C. elegans most worms are self-fertilizing XX hermaphrodites, but occasionally abnormalities in chromosome inheritance regularly give rise to individuals with only one X chromosome—these X0 individuals are fertile males (and half their offspring are male).^[23]

Other insects, including honey bees and ants, use a haplodiploid sex-determination system.^[24] In this case diploid individuals are generally female, and haploid individuals (which develop from unfertilized eggs) are male. This sex-determination system results in highly biased sex ratios, as the sex of offspring is determined by fertilization rather than the assortment of chromosomes during meiosis.

Clownfish are initially male; the largest fish in a group becomes female.

Nongenetic[link]

For many species sex is not determined by inherited traits, but instead by environmental factors experienced during development or later in life. Many reptiles have temperature-dependent sex determination: the temperature embryos experience during their development determines the sex of the organism. In some turtles, for example, males are produced at lower incubation temperatures than females; this difference in critical temperatures can be as little as 1–2°C.

Many fish change sex over the course of their lifespan, a phenomenon called sequential hermaphroditism. In clownfish, smaller fish are male, and the dominant and largest fish in a group becomes female. In many wrasses the opposite is true—most fish are initially female and become male when they reach a certain size. Sequential hermaphrodites may produce both types of gametes over the course of their lifetime, but at any given point they are either female or male.

In some ferns the default sex is hermaphrodite, but ferns which grow in soil that has previously supported hermaphrodites are influenced by residual hormones to instead develop as male.^[25]

Sexual dimorphism[link]

Common Pheasants are sexually dimorphic in both size and appearance.

Many animals have differences between the male and female sexes in size and appearance, a phenomenon called sexual dimorphism. Sexual dimorphisms are often associated with sexual selection – the competition between individuals of one sex to mate with the opposite sex.^[26] Antlers in male deer, for example, are used in combat between males to win reproductive access to female deer. In many cases the male of a species is larger in size; in mammals species with high sexual size dimorphism tend to have highly polygynous mating systems—presumably due to selection for success in competition with other males.

Other animals, including most insects and many fish, have larger females. This may be associated with the cost of producing egg cells, which requires more nutrition than producing sperm—larger females are able to produce more eggs.^[27] Occasionally this dimorphism is extreme, with males reduced to living as parasites dependent on the female.

In birds, males often have a more colourful appearance and may have features (like the long tail of male peacocks) that would seem to put the organism at a disadvantage (e.g. bright colors would seem to make a bird more visible to predators). One proposed explanation for this is the handicap principle.^[28] This hypothesis says that, by demonstrating he can survive with such handicaps, the male is advertising his genetic fitness to females—traits that will benefit daughters as well, who will not be encumbered with such handicaps.

Sex differences in humans include, generally, a larger size and more body hair in men; women have breasts, wider hips, and a higher body fat percentage.

References[link]

Further reading[link]

External links[link]

Find more about Sex on Wikipedia's sister projects:
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	Source texts from Wikisource
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	Book: Sex
Wikipedia books are collections of articles that can be downloaded or ordered in print.

• Human Sexual Differentiation by P. C. Sizonenko
• New Scientist article on Sex chromosomes in the platypus

A hoop rolling game

A toy is any object that can be used to play. Toys are associated commonly with children and pets. Playing with toys is often thought to be an enjoyable means of training the young for life in human society. Different materials are used to make toys enjoyable and cuddly to both young and old. Many items are designed to serve as toys, but goods produced for other purposes can also be used. For instance, a small child may pick up a household item and "fly" it through the air as to pretend that it is an airplane. Another consideration is interactive digital entertainment, such as a video game. Some toys are produced primarily as collector's items and are intended for display only.

The origin of toys is prehistoric; dolls representing infants, animals, and soldiers, as well as representations of tools used by adults are readily found at archaeological sites. The origin of the word "toy" is unknown, but it is believed that it was first used in the 14th century.^[1]

Toys, and play in general, are important when it comes to growing up and learning about the world around us. The young use toys and play to discover their identity, help their bodies grow strong, learn cause and effect, explore relationships, and practice skills they will need as adults. Adults use toys and play to form and strengthen social bonds, teach, remember and reinforce lessons from their youth, discover their identity, exercise their minds and bodies, explore relationships, practice skills, and decorate their living spaces.

Geometric Tiles of FroebelSet, Allow the child to use his/her creativity to create mosaics, patters, architectural buildings ^[2]

History[link]

Little horse on wheels, Ancient Greek child's toy. From a tomb dating 950-900 BCE, Kerameikos Archaeological Museum, Athens

A boy with a hoop. Hoops have long been a popular toy across a variety of cultures.

Most young humans have been said to play with whatever they can find, such as pine cones and rocks. Toys and games have been unearthed from the sites of ancient civilizations. They have been written about in some of our oldest literature. Toys excavated from the Indus valley civilization (3000-1500 BCE) include small carts, whistles shaped like birds, and toy monkeys which could slide down a string.^[3]

The earliest toys were made from materials found in nature, such as rocks, sticks, and clay. Thousands of years ago, Egyptian children played with dolls that had wigs and movable limbs which were made from stone, pottery, and wood.^[4] In Ancient Greece and Ancient Rome, children played with dolls made of wax or terracotta, sticks, bows and arrows, and yo-yos. When Greek children, especially girls, came of age it was customary for them to sacrifice the toys of their childhood to the gods. On the eve of their wedding, young girls around fourteen would offer their dolls in a temple as a rite of passage into adulthood.^[5][6]

A display of Roman toys, including several that would be familiar to children today: a doll, dice, rattles, and toy dishes for playing house

As technology changed and civilization progressed, toys also changed. Where as ancient toys were made from materials found in nature like stone, wood, and grass, modern toys are often made from plastic, cloth, and synthetic materials, oftentimes powered by batteries. Ancient toys were often made by the parents and family of the children who used them, or by the children themselves. Modern toys, in contrast, are often mass-produced and sold in stores.

This change in the nature of toys is exemplified by the changes that have taken place in one of the oldest and most universal of human toys; dolls. The earliest and most primitive dolls were simple wooden carvings and bundles of grass. Egyptian dolls were sometimes jointed so that their limbs could move realistically. By the early 20th century there were dolls that could say "mama".^[7] Today there are computerized dolls that can recognize and identify objects, the voice of their owner, and choose among hundreds of pre-programmed phrases with which to respond.^[8] The materials that toys are made from have changed, what toys can do has changed, but the fact that children play with toys has not changed.

Child development[link]

A rubber duck is a popular bathtime toy for small children.

Toys, like play itself, serve multiple purposes in both humans and animals. They provide entertainment while fulfilling an educational role. Toys enhance cognitive behavior and stimulate creativity. They aid in the development of physical and mental skills which are necessary in later life.

One of the simplest toys, a set of simple wooden blocks is also one of the best toys for developing minds. Andrew Witkin, director of marketing for Mega Brands told Investor's Business Daily that, "They help develop hand-eye coordination, math and science skills and also let kids be creative."^[9] Other toys like Marbles, jackstones, and balls serve similar functions in child development, allowing children to use their minds and bodies to learn about spatial relationships, cause and effect, and a wide range of other skills as well as those mentioned by Mr. Witkin.

Two children playing with paddle balls, a painting by the Chinese artist Su Hanchen (苏汉臣, active 1130s-1160s AD), Song Dynasty

One example of the dramatic ways that toys can influence child development involves clay sculpting toys such as Play-Doh and Silly Putty and their home-made counterparts. Mary Ucci, Educational Director of the Child Study Center of Wellesley College, demonstrates how such toys positively impact the physical development, cognitive development, emotional development, and social development of children.^[10]

Toys for infants often make use of distinctive sounds, bright colors, and unique textures. Through play with toys infants begin to recognize shapes and colors. Repetition reinforces memory. Play-Doh, Silly Putty and other hands-on materials allow the child to make toys of their own.

Educational toys for school age children of often contain a puzzle, problem-solving technique, or mathematical proposition. Often toys designed for older audiences, such as teenagers or adults demonstrate advanced concepts. Newton's cradle, a desk toy designed by Simon Prebble, demonstrates the conservation of momentum and energy.

Not all toys are appropriate for all ages of children. Some toys which are marketed for a specific age range can even harm the development of children in that range.^{[citation needed]}

Gender[link]

A toy tank with a remote control. Such toys are generally thought of as boys' toys.

Certain toys, such as Barbie dolls and toy soldiers, are often perceived as being more acceptable for one gender than the other. It has been noted by researchers that, "Children as young as 18 months display sex-stereotyped toy choices".^[11]

Playing with toys stereotyped for the opposite gender sometimes results in negative consequences from parents or fellow children. In recent years^{[citation needed]}, mainly in western countries^{[citation needed]}, it has been looked down upon for males to play with toys that were originally stereotyped as being girls' games and toys. However, it is generally not as looked down upon for females to play with toys designed "for boys", an activity which has also become more common in recent years.^[12]

Economics[link]

Toys "R" Us operates over 1,500 stores in 30 countries and has an annual revenue of US$13.6 billion

With toys comprising such a large and important part of human existence, it makes sense that the toy industry would have a substantial economic impact. Sales of toys often increase around holidays where gift-giving is a tradition. Some of these holidays include Christmas, Easter, Saint Nicholas Day and Three Kings Day.

In 2005, toy sales in the United States totaled about $22.9 billion.^[9] Money spent on children between the ages of 8 and twelve alone totals approximately $221 million annually in the U.S.^[13]

Toy makers change and adapt their toys to meet the changing demands of children thereby gaining a larger share of the substantial market. In recent years many toys have become more complicated with flashing lights and sounds in an effort to appeal to children raised around television and the internet. According to Mattel's president, Neil Friedman, "Innovation is key in the toy industry and to succeed one must create a 'wow' moment for kids by designing toys that have fun, innovative features and include new technologies and engaging content."

In an effort to reduce costs, many mass-producers of toys locate their factories in areas where wages are lower. 75% of all toys sold in the U.S., for example, are manufactured in China.^[9] Issues and events such as power outages, supply of raw materials, supply of labor, and raising wages that impact areas where factories are located often have an enormous impact on the toy industry in importing countries.

Many traditional toy makers have been losing sales to video game makers for years. Because of this, some traditional toy makers have entered the field of electronic games and are enhancing the brands that they have by introducing interactive extensions or internet connectivity to their current toys.^[14]

Types[link]

Construction sets[link]

Lincoln Logs have been a popular construction type toy in the U.S. since 1920s.

The Greek philosopher Plato wrote that the future architect should play at building houses as a child.^[15] A construction set is a collection of separate pieces that can be joined together to create models. Popular models to make include cars, spaceships, and houses. The things that are built are sometimes used as toys once completed, but generally speaking, the object is to build things of one's own design, and old models often are broken up and the pieces reused in new models.

The oldest and, perhaps most common construction toy is a set of simple wooden blocks, which are often painted in bright colors and given to babies and toddlers. Construction sets such as Lego bricks and Lincoln Logs are designed for slightly older children and have been quite popular in the last century. Construction sets appeal to children (and adults) who like to work with their hands, puzzle solvers, and imaginative sorts.

Some other examples include Bayko, Konstruk-Tubes, K'NEX, Erector Sets, Tinkertoys, and Meccano, and generic construction toys such as Neodymium magnet toys.

Dolls, animals, and miniatures[link]

A girl and her doll in the 1900s.

A doll is a model of a human (often a baby), a humanoid (like Bert and Ernie), or an animal. Modern dolls are often made of cloth or plastic. Other materials that are, or have been, used in the manufacture of dolls include cornhusks, bone, stone, wood, porcelain (sometimes called china), bisque, celluloid, wax, and even apples. Often people will make dolls out of whatever materials are available to them.

Sometimes intended as decorations, keepsakes, or collectibles for older children and adults, most dolls are intended as toys for children, usually girls, to play with. Dolls have been found in Egyptian tombs which date to as early as 2000 BC.^[4]

Dolls are usually miniatures, but baby dolls may be of true size and weight. A doll or stuffed animal of soft material is sometimes called a plush toy or plushie. A popular toy of this type is the Teddy Bear.

A distinction is often made between dolls and action figures, which are generally of plastic or semi-metallic construction and poseable to some extent, and often are merchandising from television shows or films which feature the characters. Modern action figures, such as Action Man, are often marketed towards boys, whereas dolls are often marketed towards girls.

Toy soldiers, perhaps a precursor to modern action figures, have been a popular toy for centuries. They allow children to act out battles, often with toy military equipment and a castle or fort. Miniature animal figures are also widespread, with children perhaps acting out farm activities with animals and equipment centered around a toy farm.

Vehicles[link]