Promiscuity is the practice of having casual sex frequently with different partners or being indiscriminate in the choice of sexual partners. The term can carry a moral judgement if viewed in the context of a mainstream social ideal for sexual activity to occur only within exclusive committed relationships. A common example of behavior viewed as promiscuous within the social ideals of many cultures is a one-night stand and (as seen in this 2014 survey) is often the way researchers define a society's promiscuity levels at any given time.
What sexual behavior is considered promiscuous varies between cultures, as does the prevalence of promiscuity, with different standards often being applied to different genders and civil status. Feminists have traditionally argued a significant double standard exists between how men and women are judged for promiscuity. Historically, stereotypes of the promiscuous woman have tended to be negative, such as "the slut" or "the harlot", while male stereotypes have been more varied, some expressing approval, such as "the stud" or "the player", while others imply societal deviance, such as "a womanizer". A scientific study published in 2005 found that promiscuous men and women are judged equally harshly and a recent poll showed that both genders tend to express strong preference for sexually conservative partners. However, later studies show evidence for a double standard.
Promiscuity is common in many animal species. Some species have promiscuous mating systems, ranging from polyandry and polygyny to mating systems with no stable relationships where mating between two individuals is a one-time event. Many species form stable pair bonds, but still mate with other individuals outside the pair. In biology, incidents of promiscuity in species that form pair bonds are usually called extra-pair copulations.
Accurately assessing people's sexual behavior is difficult, since strong social and personal motivations occur, depending on social sanctions and taboos, for either minimizing or exaggerating reported sexual activity.
American experiments in 1978 and 1982 found the great majority of men were willing to have sex with women they did not know, of average attractiveness, who propositioned them. No woman, by contrast, agreed to such propositions from men of average attractiveness. While men were in general comfortable with the requests, regardless of their willingness ("Why do we have to wait until tonight?", "[I'm sorry], I'm married"), women responded with shock and disgust ("You've got to be kidding", "What is wrong with you? Leave me alone").
The number of sexual partners people have had in their lifetimes varies widely within a population. A 2007 nationwide survey in the United States found the median number of female sexual partners reported by men was seven and the median number of male partners reported by women was four. The men possibly exaggerated their reported number of partners, women reported a number lower than the actual number, or a minority of women had a sufficiently larger number than most other women to create a mean significantly higher than the median, or all of the above (see Pareto principle). About 29% of men and 9% of women reported to have had more than 15 sexual partners in their lifetimes. Studies of the spread of sexually transmitted diseases consistently demonstrate a small percentage of the studied population has more partners than the average man or woman, and a smaller number of people have fewer than the statistical average. An important question in the epidemiology of sexually transmitted infections is whether or not these groups copulate mostly at random (with sexual partners from throughout a population) or within their social groups (assortative mixing).
A 2006 systematic review (analyzing data from 59 countries worldwide) found no association between regional sexual behavior tendencies, such as number of sexual partners, and sexual-health status. Much more predictive of sexual-health status are socioeconomic factors like poverty and mobility. Other studies have suggested that people with multiple casual sex partners are more likely to be diagnosed with sexually transmitted infections.
Severe and impulsive promiscuity, along with a compulsive urge to engage in illicit sex with attached individuals is a common symptom of borderline personality disorder, histrionic personality disorder and antisocial personality disorder but most promiscuous individuals do not have these disorders.
In 2008, a U.S. university study of international promiscuity found that Finns have had the largest number of sex partners in the industrialized world, and British people have the largest number among big western industrial nations. The study measured one-night stands, attitudes to casual sex, and number of sexual partners. Within Britain, in 2014 a nationwide survey named Liverpool the most promiscuous city in the UK.
Britain's position on the international index "may be linked to increasing social acceptance of promiscuity among women as well as men". Britain’s ranking was "ascribed to factors such as the decline of religious scruples about extramarital sex, the growth of equal pay and equal rights for women and a highly sexualised popular culture".
The top-10-ranking OECD nations with a population over 10 million on the study's promiscuity index, in descending order, were the United Kingdom, Germany, the Netherlands, the Czech Republic, Australia, the United States, France, Turkey, Mexico, and Canada.
A nonscientific survey conducted in 2007 by condom-maker Durex measured promiscuity by a total number of sexual partners. The survey found Austrian men had the highest number of sex partners of males globally with 29.3 sexual partners on average. New Zealand women had the highest number of sex partners for females in the world with an average of 20.4 sexual partners. In all of the countries surveyed, except New Zealand, men reported more sexual partners than women.
One review found the people from developed Western countries had more sex partners than people from developing countries in general, while the rate of STIs was higher in developing countries.
According to the 2005 Global Sex Survey by Durex, people have had on average nine sexual partners, the most in Turkey (14.5) and Australia (13.3), and the least in India (3) and China (3.1).
A 1994 study in the United States, which looked at the number of sexual partners in a lifetime, found 20% of heterosexual men had only one partner, 55% had two to 20 partners, and 25% had more than 20 partners. More recent studies have reported similar numbers. Earlier studies found homosexual men were more likely to have very large numbers of sexual partners.
A 1989 study found a very high number of partners (over 100) to be present though rare among homosexual males. General Social Survey data indicates that the distribution of partner numbers among men who have sex exclusively with men and men who have sex exclusively with women is similar, but that differences appear in the proportion of those with very high number of partners, which is larger among gay men, but that in any case makes up a small minority for both groups. OkCupid discovered a similar pattern in the data collected from its vast number of users, published in 2010: the median number of self-reported lifetime sexual partners for both gay and straight men was six; however, a small minority of gay men (2%) were having a disproportionate share of all self-reported gay sex (23%). According to updated OkCupid data published in 2014, gay male users self-reported a lower median of lifetime sex partners than straight male users: four for gay men and five for straight men. A 2007 study reported that two large population surveys found "the majority of gay men had similar numbers of unprotected sexual partners annually as straight men and women."
The words 'womanizer', 'playboy', 'stud', 'player', 'ladies' man', 'lady killer', and 'rake' may be used in reference to a man who has romantic affairs or sexual relations, or both, with women, and who will not marry or commit to a relationship. The names of real and fictional seducers have become eponymous for such promiscuous men. The most famous are Lord Byron, John F. Kennedy, Wilt Chamberlain, Howard Hughes, and the historical Giacomo Casanova (1725–98). Others include Elvis Presley, Frank Sinatra, Dean Martin, and Steve McQueen. Famous fictional seducers include Don Juan, who first appeared in the 17th century, the fictional Vicomte de Valmont from Choderlos de Laclos's 18th-century novel Les Liaisons Dangereuses (Dangerous Liaisons), and Lothario from Nicholas Rowe's 1703 play The Fair Penitent. James Bond, Chuck Bass, James T. Kirk, Tony Stark, Glenn Quagmire, Bruce Wayne, Charlie Harper, Sam Malone, Joey Tribbiani, Popeye Doyle, Donald Draper, Hank Moody, Barney Stinson and Drake Parker are fictional characters who can be considered womanizers.
During the English Restoration period (1660–88), the term 'rake' was used glamorously: the Restoration rake is a carefree, witty, sexually irresistible aristocrat typified by Charles II's courtiers, the Earl of Rochester and the Earl of Dorset, who combined riotous living with intellectual pursuits and patronage of the arts. The Restoration rake is celebrated in the Restoration comedy of the 1660s and the 1670s. After the reign of Charles II, and especially after the Glorious Revolution of 1688, the rake was perceived negatively and became the butt of moralistic tales in which his typical fate was debtor's prison, permanent venereal disease, and, in the case of William Hogarth's A Rake's Progress, syphilis-induced insanity and internment in Bedlam.
In 1994, a study in the United States found almost all married heterosexual women reported having sexual contact only with their husbands, and unmarried women almost always reported having no more than one sexual partner in the past three months. Lesbians who had a long-term partner reported having fewer outside partners than heterosexual women. More recent research, however, contradicts the assertion that heterosexual women are largely monogamous. A 2002 study estimated that 45% to 55% of married heterosexual women engage in sexual relationships outside of their marriage. While the estimates for heterosexual males in the same study were greater (50–60%), the data indicate a significant portion of married heterosexual women have or have had sexual partners other than their spouse, as well.
Since at least 1450, the word 'slut' has been used, often pejoratively, to describe a sexually promiscuous woman. In and before the Elizabethan and Jacobean eras, terms like "strumpet" and "whore" were used to describe women deemed promiscuous, as seen, for example, in John Webster's 1612 play The White Devil. In some tribes of Sierra Leone, "A woman who is a Paramount Chief may have sexual intercourse with as many men as she pleases." That is however an exception, see Polygamy in Sierra Leone, where polygyny is much more prevalent.
It has been found that women are much more likely to sexually fantasize about and be attracted to extra-pair men during the fertile phase of the menstrual cycle than the luteal phase. Whereas attraction to the primary partner does not change depending on the menstrual cycle. 
Evolutionary psychologists propose that a conditional human tendency for promiscuity is inherited from hunter-gatherer ancestors. Promiscuity increases the likelihood of having children, thus "evolutionary" fitness. According to them, female promiscuity is advantageous in that it allows females to choose fathers for their children who have better genes than their mates, to ensure better care for their offspring, have more children, and as a form of fertility insurance. Male promiscuity was likely advantageous because it allowed males to father more children.
Primitive promiscuity (or original promiscuity) was the (largely discredited) 19th-century hypothesis that humans originally lived in a state of promiscuity or "hetaerism" prior to the advent of society as we understand it.
Many animal species, such as bonobos and chimpanzees, are promiscuous as a rule; they do not form pair bonds. Although social monogamy occurs in about 90% of avian species and about 3% of mammalian species, an estimated 90% of socially monogamous species exhibit individual promiscuity in the form of extra-pair copulations (copulation outside the pair bond).
In the animal world, some species, including birds such as swans and fish such as Neolamprologus pulcher, once believed monogamous, are now known to engage in extra-pair copulations. One example of extra-pair fertilization (EPF) in birds is the black-throated blue warblers. Though it is a socially monogamous species, both males and females engage in EPF.
- Female promiscuity
- Sexual addiction
- Sociosexual orientation
- Sperm competition
- "Promiscuous - definition of promiscuous by the Free Online Dictionary". The Free Dictionary. Retrieved 21 September 2013.
- "UK’s most promiscuous city in ‘one night stand’ poll revealed". Metro.co.uk. Associated Newspapers Limited.
- Marks, Michael; Fraley, R. (2005). "The Sexual Double Standard: Fact or Fiction?". Sex Roles 52 (3-4): 175–186. doi:10.1007/s11199-005-1293-5.
- ""Would You Go To Bed With Me Tonight?": Stigma and the Sexual Double Standard - - - Science of Relationships". scienceofrelationships.com.
- "Motives for the Sexual Double Standard: A Test of Female Control Theory". SPSP.
- Lipton, Judith Eve; Barash, David P. (2001). The Myth of Monogamy: Fidelity and Infidelity in Animals and People. San Francisco: W.H. Freeman and Company. ISBN 0-7167-4004-4.
- Clark, Russell D. III; Hatfield, Elaine (1989). "Gender Differences in Receptivity to Sexual Offers" (PDF). Journal of Psychology & Human Sexuality 2 (1): 39–55. doi:10.1300/J056v02n01_04.
- "Average man sleeps with 7 women - Health - Sexual health - NBC News". msnbc.com.
- Wellings K, Collumbien M, Slaymaker E, et al. (2006). "Sexual behaviour in context: a global perspective" (PDF). Lancet 368 (9548): 1706–28. doi:10.1016/S0140-6736(06)69479-8. PMID 17098090. Lay summary – BBC (1 November 2006).
- Garcia JR, Seibold-Simpson SM, Massey SG, Merriwether AM (2015). "Casual Sex: Integrating Social, Behavioral, and Sexual Health Research". In DeLamater J, Plante RF. Handbook of the Sociology of Sexualities. Springer. p. 215. doi:10.1007/978-3-319-17341-2_12.
- Hull, J. W.; Clarkin, J. F.; Yeomans, F. (1993). "Borderline personality disorder and impulsive sexual behavior". Psychiatric Services 44 (10): 1000–1001. doi:10.1176/ps.44.10.1000.
- Waite, Roger (2008-11-30). "Britain on top in casual sex league". The Times (London). Retrieved 2010-05-22.
- Beckford, Martin; Jamieson, Alastair (2008-11-30). "Britain is among casual sex capitals of the Western world, research claims". The Daily Telegraph (London). Retrieved 2010-05-22.
- "British top promiscuity study". UPI.
- "Liverpool named UK’s most promiscuous city". themetro.co.uk. Mark Molloy.
- New Zealand women most promiscuous The Sydney Morning Herald
- http://www.data360.org/pdf/20070416064139.Global%20Sex%20Survey.pdf , page 6
- Seidman, S. N.; Rieder, R. O. (1994). "A review of sexual behavior in the United States". Am J Psychiatry 151: 330–341. doi:10.1176/ajp.151.3.330.
- Lehmiller, J. J. (2012). "What’s Your Number?". The Psychology of Human Sexuality.
- Friedman, Richard C.; Downey, Jennifer I. (October 6, 1994). "Homosexuality". New England Journal of Medicine (Massachusetts Medical Society) 331 (14): 923–930. doi:10.1056/NEJM199410063311407. PMID 8078554.
- Tim Fisher (November 1, 2006). A Response to David Glesne, Regarding Promiscuity Statisticsin the context of his book, Understanding Homosexuality (Report).
- Christian Rudder (October 12, 2010). "Gay Sex vs. Straight Sex". OkCupid.
- Christian Rudder (2014). Dataclysm: Who We Are (When We Think No One's Looking). Crown. p. 180. ISBN 978-0385347372.
The number of reported lifetime sex partners among all four groups is essentially the same. The median for gay men and straight women is four; for lesbians and straight men, it's five, but just barely...
- Sexual Behavior Does Not Explain Varying HIV Rates Among Gay And Straight Men
- Goodreau SM, Golden MR (October 2007). "Biological and demographic causes of high HIV and sexually transmitted disease prevalence in men who have sex with men". Sex Transm Infect 83 (6): 458–62. doi:10.1136/sti.2007.025627. PMC 2598698. PMID 17855487.
- Julie Coleman (1999). Love, Sex and Marriage: A Historical Thesaurus. Rodopi. ISBN 90-420-0433-9.
- Atwood, Joan D.; Limor Schwartz (2002). "Cyber-Sex The New Affair Treatment Considerations". Journal of Couple & Relationship Therapy: Innovations in Clinical and Educational Interventions 1 (3): 37–56. doi:10.1300/J398v01n03_03.
- Harper, Douglas. "slut". Online Etymology Dictionary.
- Vergette : Certain Marriage Customs of some of the Tribes in Sierra Leone, p. 10. quoted in Edward Westermarck : The History of Human Marriage. Allerton Book Co., New York, 1922. vol. 3, p. 153
- Thornhill, Randy; Gangestad, Steven W. (2008). The evolutionary biology of human female sexuality. New York: Oxford University Press. pp. 244–245. ISBN 978-0-19-534098-3.
- Anthony Browne Women are promiscuous, naturally. Some Scientists now believe infidelity is a genetic mechanism for creation of healthy children. The Observer, September 3, 2000.
- Westermarck, chap. 3 p. 103-4
- Bachofen, Das Mutterrecht, pp. xix-xx, 10
- Bachofen, Antiquarische Briefe pp.20-
- McLennan, Morgan, Lord Avebury, Giraud-Teulon, Lippert, Kohler, Post, Wilken, Kropotkin, Wilutzky
- Bloch, Iwan Sexual Life of Our Time, pp. 188-194
- de Waal, Frans B. M. (March 1995). "Bonobo Sex and Society" (PDF). Scientific American 272 (3): 58–64. Bibcode:1995SciAm.272c..82W. doi:10.1038/scientificamerican0395-82. PMID 7871411. Retrieved 21 December 2011.
- Reichard, U.H. (2002). "Monogamy—A variable relationship" (PDF). Max Planck Research 3: 62–7. Retrieved 24 April 2013.
- Research conducted by Patricia Adair Gowaty. Reported by Morell, V. (1998). "Evolution of sex: A new look at monogamy". Science 281 (5385): 1982–1983. doi:10.1126/science.281.5385.1982. PMID 9767050.
- Chuang, H.C.; Webster, M.S.; Holmes, R.T. (1999). "Extrapair Paternity and Local Synchrony in the Black-Throated Blue Warbler". The Auk. 3 116 (3): 726–736. doi:10.2307/4089333.
- Chakov, Kelly Nineteen Century Social Evolutionism
- Fortes, Meyer (2005) Kinship and the Social Order: The Legacy of Lewis Henry Morgan ISBN 0-202-30802-2 pp. 7–8
- Lehrman, Sally The Virtues of Promiscuity (2002)
- Lerner, Gerda (1986) Women and History vol. 1: The Creation of Patriarchy  ISBN 978-0-19-503996-2
- Lerner, Gerda The Origin of Prostitution in Ancient Mesopotamia Signs, Vol. 11, No. 2 (Winter, 1986), pp. 236–254
- Schmitt, David P. Sociosexuality from Argentina to Zimbabwe: A 48-nation study of sex, culture, and strategies of human mating Behavioral and Brain Sciences (2005) 28, 247-311
- Miller, Gerrit S. Jr. (1931) The Primate Basis of Human Sexual Behavior The Quarterly Review of Biology, Vol. 6, No. 4 (Dec., 1931), pp. 379–410
- Westermarck, Edward  (2003) History of Human Marriage Part 1 Kessinger Publishing ISBN 0-7661-4618-9
- Weston, Kath (1998) Long Slow Burn: Sexuality and Social Science ISBN 0-415-92043-4
- Woock, Randy (2002) Promiscuous Women Should Be Praised
- Rinaldi, Robin, The Wild Oats Project: One Woman's Midlife Quest for Passion at Any Cost, Sarah Crichton Books (March 17, 2015), hardcover, 304 pages ISBN 0374290210 ISBN 978-0374290214