The Jay Buddy Effect

Some years ago, Jay Buddy made the following conjecture:

The Jay Buddy Effect: Men born towards the tail end of the Baby Boom face intense competition finding a wife.

Jay Buddy’s reasoning was that since women tend to prefer older men, it follows inexorably that men born towards the tail end of the Baby Boom are competing for a smaller cohort of women born after the Boom.

On closer examination, Jay Buddy’s thesis seems based on three assumptions (have I left any out?):

  1. Women preferentially marry older men.
  2. Within an age cohort, approximately equal numbers of males and females are born, with perhaps a slight preponderance of males (see below).
  3. Between 1946 and 1964, there was a baby boom. The U.S. Census Bureau considers someone born between 1946 and 1964 to be a Baby Boomer.

Let’s examine each of these in greater detail.

Male-female age asymmetry at time of marriage. Women tend to marry older men; equivalently, men tend to marry younger women. This isn’t a normative statement, but merely a fact. Certainly there are exceptions here and there (exceptions that prove the general rule), but I’m talking about population distributions, the central tendency.

There may be evolutionary reasons for this. For example, in a 2007 article entitled Fertile Times for May-December Couples, science journalist John Bohannon summarizes a study of 10,000 Swedish baby boomers, both men and women, born between 1945 and 1955. The study found that choosing a younger wife or an older husband paid off in terms of children born: couples in which the husband was about 5 years older produced approximately 5% more children than same-age couples. On a population-wide scale, that’s a big difference.

Sex ratio at birth. Back in medical school, I heard a statistic that about 51 boys are born for every 50 girls. (Upon hearing this I toyed with the idea of adopting the sobriquet The 51st Guy.) This seems to be approximately true, as confirmed by this 2005 C.D.C. report (here’s the corresponding Fact Sheet), although the ratio may be decreasing. (Conjecture: young males probably have a higher death rate due to hypertestosteronemia and general machismo, so the ratio may balance out.) Even if the ratio were equal, it seems to me that Jay Buddy’s conjecture would still hold

The Baby Boom. During the decades immediately following World War II, there was a baby boom. The U.S. Census Bureau considers someone born between 1946 and 1964 to be a Baby Boomer. Here’s a public domain graphic from Wikipedia illustrating the Baby Boom:

Number of births in the United States, 1934 to present

Number of births in the United States, 1934 to present

Now, Jay Buddy wasn’t a professional demographer or social scientist; he came up with this conjecture on his own! And it appears that he may have been on to something. For example, in the book Sexuality across the Life Course (1994), anthropologist Jane B. Lancaster writes:

Guttentag and Secord (1983) pointed to less sweeping historic trends when they evaluated the shorter-term effect on marraige forms and sex roles of demographic fluctuations such as the baby boom and its effect on the supply of mates given the strong preference of women to marry men of older age (proven prospects) or superior status (James 1989). Women born early in the baby-boom generation found themselves in oversupply; men born at the end of the period find themselves either competing intensely for a much smaller cohort of younger women or else compromising their reproductive interests by marrying older women with reduced reproductive potential.

Dr. Lancaster references a 1983 book by University of Houston social scientists Marcia Guttentag and Paul Secord entitled Too Many Women?: The Sex Ratio Question. If I understand correctly, the thesis of the book is that imbalances in the sex ratio can result in large-scale social consequences. The book also gives evidence that in 1970 there were only two eligible males for every three eligible women (cf. p. 175, and Table 7.1). In other words, there were “too many women” at the beginning tail of the Baby Boomer generation. The Jay Buddy Effect is the converse; there are “too many men” at the tail end.

Consider this excerpt from a 2001 TIME article entitled Welcome, America, to the Baby Bust:

Marriage prospects should improve for women in the baby-bust generation. Women tend to marry men a few years older than themselves, and younger women will find larger numbers of potential spouses among the baby boomers.

The author doesn’t consider the obvious flip side, which is that men born at the trailing end of the Baby Boom face increased competition among themselves for those younger women in the baby-bust generation: the Jay Buddy Effect.

And, in a 1996 interview, David Buss, author of The Evolution of Desire, said:

When the baby boomers reach sexual maturity, since women desire men who are older, the pool of men they desire is much smaller, and so for these men who were born just before the baby boom, there’s a surplus of women. So you’d expect to see a lot more short-term mating going on in that group. And that coincides with what happened in the sexual revolution of the late sixties and early seventies – a surplus of women reaching sexual maturity. At the tail end of the baby boom you get just the opposite effect – women born at the end of the baby boom have many more older men to choose from.

And finally, here’s an excerpt from a 1988 New York Times article entitled Coming Soon: More Men than Women:

For two decades [keep in mind this is a 1988 article — Markov] there has been a shortage of eligible males largely due to the baby boom – the 75 million Americans born between 1947 and 1964. The reason is that first- time bridegrooms tend to marry women who are two to three years younger. This trend has remained constant for decades. And since each year of the baby boom until 1957 saw a larger number of births than the previous year, each age group of older males sought partners among a younger and larger group of females. This meant that the number of older men was too small for the larger group of younger women. But once the largest group of baby boomers passed through its 20’s – which happened in 1987 – then the younger, remaining baby boom males had to begin looking for their female companions from among a smaller group of females from the post 1957 ”baby bust” generation. For these men, finding wives two to three years younger will not be as easy as it was in the past.

The N.Y.T. article then mentions Guttentag and Secord’s hypothesis that during a time of a relative surplus of women, you get an era of relaxed sexual mores, as women have to compete for scarce men: the Era of Free Love. But during a time of a relative surplus of men, one might expect that

… a protective morality develops that favors monogamy for women, limits their interactions with men, and shapes female roles in traditional domestic directions.

In summary, for men of a certain age, the Jay Buddy Effect presents a daunting problem. Perhaps the solution is for men born at the trailing end of the Baby Boomer generation to pair off with women born at the beginning of the Boom!


In recent years, it has been reported that there is now a huge preponderance of boys relative to girls in China and India due to female infanticide. For example, in 2005 the ratio was 118 males born for every 100 females in China. What will be the effects on these societies?


As a final note, Russia apparently has a reverse sex ratio problem. In 2005, there were 875 men for every 1000 women in Russia (Glenn E. Curtis, ed., Russia: A Country Study. Washington: GPO for the Library of Congress, 1996).

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Published in: on 20 January 2009 at 11:30 am  Leave a Comment  
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