Sex and The Pareto Principle

September 14, 2010

Do 20% of the men get 80% of the women? I’ve come across this claim repeatedly, though the application of the 80/20 rule varies. Sometimes it’s stated that 20% of the men get 80% of the sex, which is actually a very different claim.

I felt the need to understand exactly what the data says, if anything, in support of the Pareto Principle as it applies to the distributution of sex. Are we talking about 80% of all women? Sexually active women? Women in their 20s, when they are at their peak of fertility and beauty? Or, as in Hollenhund’s version, is it just a question of the frequency of sex, even with one partner? In that case, how to incorporate the male preference for sexual variety?

Are 20% of the guys getting all the nookie?

The Origin of the Claim

I. The Pareto Principle

The Pareto Principle (also known as the 80/20 Rule) states that, for many events, roughly 80% of the effects come from 20% of the causes. Business management thinker Joseph M. Juran suggested the principle and named it after Italian economist Vilfredo Pareto, who observed in 1906 that 80% of the land in Italy was owned by 20% of the population; he developed the principle by observing that 20% of the pea pods in his garden contained 80% of the peas. It is a common rule of thumb in business; e.g., “80% of your sales come from 20% of your clients.” The Pareto Principle is an observation, not a law of nature, but it holds roughly true in many areas of life.

II. The Fallout of the Sexual Revolution

The anonymous essay There is No Longer Someone for Everyone lays out succinctly why the 80/20 Rule applies to the sexual marketplace. It is this explanation that I found so intuitively obvious when I first encountered it. Excerpted from the essay:

The Attractiveness Hierarchy

In the monogamous marriage system of the past, the majority of men and women found mates and got married. In that system, singles knew roughly where they were ranked in overall attractiveness and married a mate of roughly equal rank as soon as they could, usually by their early 20’s.

In today’s society, birth control [means that women] can have sex without marriage, engaging in temporary physical relationships…while they wait and hope for Mr. Right. Men have a greater evolved desire for unfettered sex, and generally prefer more sex partners rather than a commitment to marriage and raising children. Because women are willing to have premarital sex, the attractive men who have ready access to many new sex partners have little incentive to pursue marriage at all. They generally prefer to circulate among women rather than settle down.

Circulating around the Pool

The promiscuous system allows very attractive men to avoid commitment and be continually available for sex. Because these men can have more sex, women have sexual access to more attractive men than they would have been able to attract as marriage partners under the monogamous system. For most men, [this] means that the [most] desirable men…can monopolize many of the women. By having many relationships, many sex partners and even multiple wives in serially monogamous fashion, the most attractive men can consume the prime reproductive years of multiple women…When some men consume more than their share of women, there will necessarily be other men, lower on the attractiveness hierarchy, who will have no suitable women available for marriage at all. This also means that all of the men who are not at the top of the hierarchy must lower their standards.

Women who are accustomed to having sex with highly attractive men don’t want to “settle” and marry the kind of less sexy man that would be willing to marry. Men don’t want to to be settled for, either. This means that both men and women remain circulating in the dating pool for long periods without settling into marriage…As promiscuity increases, marriage declines and fewer singles can find lifelong partners.

It’s a rather grim tale, and one that I continue to find compelling. It works from an economics standpoint. What is not clear is how severe this disequilibrium is. Even a slight imbalance – say 45% of the men getting 55% of the women, would wreak havoc in the SMP, explaining great frustration on the part of many men. And what of the frustration of women? If the 80/20 Rule holds up, then the vast majority of women can be assumed to be getting what they want – short-term sexual liaisons when they’re at their physical peak. However, it also means that they’re acting against their own best interests if marriage is their long-term goal. If the Pareto Principle doesn’t apply here, then we’re talking about a very different distribution of sex, one in which a much smaller group of promiscuous women is having sex with a roughly equivalent sized pool of promiscuous men.

Furthermore, if we define the 80/20 Rule to mean that 20% of the men are getting 80% of the intercourse, we may be describing the sexual advantage inherent in committed sexual relationships, rather than a string of casual hookups, each one of which requires some investment of time and energy, even for the most attractive men.

Surprisingly, I cannot find a single study addressing this question. However, there is data available, most notably from the CDC:

The Data

CDC (2007)

1. Partners in the Last Year

%M (20-59)15.467.916.710.4

* (age 15-44)

2. Lifetime Sexual Partners

% All Males16.633.820.728.96.8
% All Females25.044.421.29.43.7

3.  Partners in the Last Year by Age

012 or more
20-29 M15.753.231.1
20-29 F15.166.019.0
30-39 M15.669.614.8
30-39 F9.479.611.0

4. Lifetime Sexual Partners by Race

Mexican American M23.838.
Mexican American F45.
Non-Hispanic White M16.634.821.327.46.2
Non-Hispanic White F24.
Non-Hispanic Black M6.422.
Non-Hispanic Black F13.047.227.312.55.0

5. Age First Had Sex

% F96413016

6. Total Number of Sex Partners ABC News Poll (2004)

“Overall, women report an average of six sex partners in their lifetimes; men, 20. But a better gauge of sexual activity for most people is the median, the midpoint between the high and low: Women report a median of three sex partners; men, a median of eight.

The averages are higher because a small number of individuals — especially men — report a very large number of partners. Five percent of the men in this sample reported having had 99 or more sex partners, including four who reported 200, three who reported 300 and one who reported 400. Among women, one percent reported 99 or more partners; the high was 100 (reported by two women).”


7. Married Sex vs. Single Sex (ABC Poll)

“Older singles (age 30 and up) are much less likely to be involved in a sexual relationship (29 percent) and much less satisfied with their sex lives.”

Married < 3 yrs.Married > 10 yrs.
% Have sex at least several times a week7232
% Sex life very exciting5829
% Enjoy sex a great deal8770

8. Frequency of Sex During Previous Year (ABC Poll)

NeverFew Times Past YearFew Times Past Month2-3 Xs/week4+ Xs/week
% Unmarried M232526197
% Unmarried F322324155
% Married M11343367
% Married F31247324

What Can We Conclude From the Data?

1. 90% of women have 0-1 partners within a given year, compared to 83% of men. Defining promiscuous as 3+ partners per year, only 10% of men and 7% of women aged 15-44 fit the criterion. (1)

2. About half of all men will have 7+ sexual partners in their lifetime, compared with less than a third of women. (2)

3. In a Pareto Principle distribution, the male median for lifetimes sexual partners should be lower than the female median. In this case the reverse is true. (2)

Female: Negative Skew

4. About 29% of men will have 15+ partners in their lifetime, compared with about 9% of women. This is a considerably higher number than the 80/20 rule would suggest, assuming that one defines men with 15+ partners as sexually successful. (2)

5. Nearly a third of men in their 20s have 2+ partners a year, compared with half that for men in their 30s, most likely reflecting a shift in marital status. The same pattern is true for women, dropping from 19% to 11% in the same age period. Proportionally, women curtail the number of partners more than men do from their 20s to 30s, probably reflecting the younger average age at marriage for women. (3)

6. Only 16% of men in their 20s have gone without sex in the last year, and that number stays steady in the 30s. This belies the notion that a large majority of males has zero access to sex. Conversely, only 19% of women in their 20s have had more than one partner in the last year, and two thirds had one partner. This belies the notion that the majority of women are “riding the cock carousel” while in their prime. (3)

7. Race is a strong predictor of the number of sexual partners. Breaking down stats by race tells a very different story than the composite by sex alone. (4)

Note: It is unclear whether the forces are cultural, religious, or based on the marriage rate. Comparing three economic strata (poverty level, 1-2 x’s poverty level and 2+ x’s poverty level) did not materially affect results.

  • Mexican American women are significantly more chaste than other women, with a full 45% claiming 0-1 partners, compared to 24% of white women and 13% of black women.
  • The intraracial median ratio is .36 for Mexican Americans, .60 for whites, and .40 for blacks. This suggests that white women are the most promiscuous relative to their same-race counterparts, though they have fewer overall sexual partners than black women do.
  • The median number of sexual partners for black males is double that for white males, and 2.7 times greater than for Mexican American males.
  • The median for black females is 1.4 that of white females, and 2.9 times the rate of Mexican American females.

8. The average age of the loss of virginity is very similar for both men and women, with women skewing slightly older. The number of lifetime virgins is the same for both sexes: 4%. (5)

9. The mean and median number of sex partners for men are more than triple the number for women. (6)

10. Marrieds have far more sex than singles. Only 29% of unmarried people over 30 are involved in a sexual relationship. A third of married men have sex 2-3 times per week, compared to a fifth of unmarried men. Only 7% of men have sex four or more times per week, whether married or unmarried. Not surprisingly, 87% of people married less than three years enjoy sex a great deal, compared with 70% who feel the same way after 10 years of marriage. (6,7)

11. A third of unmarried women have not had sex in the past year, compared with less about a quarter of the men. About 20% of single women have sex two or more times per week. (7)


What are the limitations of the Data?

1. Interpretation of the data will depend on how you define sexual success for males. However, we may say that even if 14 partners in a lifetime represents abject failure in the sexual marketplace, 29% are successful in surpassing that number. Obviously, the definition of success will vary by age, sex drive, moral values and personality.

For example, in a recent post, Roissy claimed that 10% of men aged 15-44 having had three or more partners in the last year was evidence 90% of women are eagerly riding the cock carousel in a frenzy of unrestrained hypergamy. Commenter MQ questioned Roissy’s interpretation of the data, suggesting that if anything it proved the reverse, especially in light of the fact that less than 7% of women had that many partners.

Roissy’s reponse:

Nice strawman, gaywad. Maybe in your beta world, action means monogamous pairings, but in normal man world, action means having sexual access to lots of  babes.

2. The data is factual, but should be considered in context relative to the history of the SMP. From the NYXs Tierney Lab blog, Roy Baumeister, evo psych god, in 2007:

While it’s true that about half of all the people who ever lived were men, the typical male was much more likely than the typical woman to die without reproducing. Citing recent DNA research, Dr. Baumeister explained that today’s human population is descended from twice as many women as men. Maybe 80 percent of women reproduced, whereas only 40 percent of men did.

This suggests that the number of men practicing involuntary abstinence will never drop to zero. It may even be true that more men have greater access to sex today than they did in previous eras.

3. There is no consistent definition of sex (Kinsey):

There is wide variability in what people consider included in “having sex”. In a recent study at The Kinsey Institute, nearly 45% of participants considered performing manual-genital stimulation to be “having sex,” 71% considered performing oral sex to be “sex,” 80.8% for anal-genital intercourse. Considerations of “sex” also varied depending on whether or not a condom was used, female or male orgasm, and if the respondent was performing or receiving the stimulation.

With participants ranging from 18 to 96 years, the oldest and youngest groups of men were less likely to consider some behaviors as “sex”.

4. People lie when they answer questions about their sex lives. This is true for all studies pertaining to sex, whether anonymous or not. It taints the data, but its effect is impossible to gauge exactly.

5. The data does not speak to motivation or intent for either sex. One commenter at Roissy’s suggested that the numbers represent sexual access for men, and sexual willingness for women. That is, the system of rewards and punishments is different for each sex, creating different incentives, which are not addressed in the data.

6. There is little evidence quantifying the sexual behaviors of college students as a discrete population. One 2001 study found that 39% of women enter college as virgins, and a third of those (13% total) graduate as virgins. A study by Kathleen Bogle, author of Hooking Up: Sex, Dating, and Relationships on Campus, found that the number of sexual partners per year for male students dropped from 2.1 in 2000 to 1.6 in 2006, though the cause was not determined.


I. The numbers do not support the claim that most women have casual sex with impunity through their 20s, then seek a sexually inexperienced male to settle down with. Rather, the data supports the idea that the numbers of promiscuous men and women are similar, though there are more promiscuous men than women. Most likely, this population is sexually active with one another. For the vast majority of Americans who do not have a high number of partners either lifetime, or within the last year, the numbers are also similar, though again, men are more promiscuous.

II. The data does not refute or confirm the concept of female hypergamy, which is the desire of the female to pair with a male of equal or higher status than herself. Within the ranks of promiscuous males and females we may still conclude based on anecdotal observation that some women are more willing to have sex with the attractive men they would otherwise not have access to as a way of increasing their social status. However, that number is a minority, though perhaps higher than the 6.8% for all women aged 20-29 who had 3+ partners in the last year.

III. A relatively small number of promiscuous men is having sex with a relatively small number of promiscuous women.


52 million unmarried American males (45%), 63.5 million married American males (55%)

Weighted formula using Table 7, Frequency of Sex During Previous Year

  • Never = 0 acts of intercourse
  • Few times past year = 6 acts
  • Few times past month = 72 acts/year
  • 2-3 times per week = 120 acts/year
  • r4+ times per week = 208 acts/year

Result: 2,994,160,000 acts unmarried intercourse per year in U.S. (35%) 5,683,250,000 acts married intercourse per year in U.S. (65%)

The demonstrated applications of the Pareto Principle to the sexual marketplace suggest that marriage is the most effective way of getting regular access to frequent sex. It also confirms that the vast majority of American women and men are conservative in their sexual habits.

The population is effectively divided into two groups:

  • A promiscuous minority of both men and women.

  • A majority of both men and women having sex with a small number of people during their lifetimes.


Whether you consider this good or bad news depends on your sex and your appeal to its opposite.