34 S C I E N T I F I C A M E R I C A N O C T O B E R 2 0 0 5

SCANnews

One of the most underappreciated forc-es affecting life in the U.S. is the sex ratio. Generally defi ned as the number

of males per 100 females, it has a profound bearing on several issues, not least of which is the status of women.

Before World War I, immigrants, who tended to be predominantly male, kept the ratio high. Restrictive legislation in the 1920s and the Great Depression of the 1930s reduced the infl ux to a trickle. Begin-ning in the 1940s, lung cancer and cardio-vascular disease, both of which affected men far more than women, resulted in an increasing proportion of females. The rise in the ratio since 1970 has resulted from a greater reduction in mortality among males than females. Increasing illegal immigra-tion, which brings in more males than fe-males, has apparently offset the effect of legal immigration, which now tends to in-volve more females than males.

The falling ratios between 1920 and 1970 led to delayed marriage [see “A Surplus of Women,” By the Numbers, April 2004]. More important has been the effect on gen-der relations, according to two social psy-chologists, the late Marcia Guttentag of Harvard University and Paul F. Secord of the University of Houston. They see the decline in the sex ratio during this period as one of the key contributors to modern feminism.

Until well past the middle of the 20th century, men dominated women because of

their control of government, religion and business. They maintained a superior legal position and imposed traditional notions of patrimony. Women generally held sway only in the brief time before marriage, when they could choose among suitors.

With the decline in the number of mar-riageable men beginning about 1920, wom-en were at a double disadvantage, because men could be more choosy while retaining many of the advantages of a more patriarchal era. The reaction of many women to their growing disadvantage was, according to Guttentag and Secord, to redefi ne their rela-tionship to men and to strive for indepen-dence. These developments came to a head in the feminist movement of the 1960s.

The rising sex ratios of the past few de-cades means that American women of mat-ing age are becoming, for the second time in U.S. history, a scarce commodity in the marriage market, although over the foresee-able future they will not be as rare as in ear-lier times. Women’s advantageous sex ratio, together with greater legal protections than ever before and their growing superiority in educational achievement, could lead, argu-ably, to an unprecedented situation in which they become the dominant sex.

Next month: Sex ratio and crime.

Rodger Doyle can be reached at rodgerpdoyle@verizon.net

More Boys Than GirlsSKEWED RATIO MAY LEAD TO THE NEXT SEXUAL REVOLUTION BY RODGER DOYLE

BY

THE

NU

MB

ER

S

Too Many Women? The Sex Ratio Question. Marcia

Guttentag and Paul F. Secord. Sage Publications, 1983.

Consequences of Imbalanced Sex Ratios: Evidence from

America’s Second Generation. Josh Angrist. National Bureau of

Economic Research, Working Paper No. 8042, December 2000.

Available at www.nber.org/papers/W8042

The Human Dichotomy: The Changing Numbers of Males

and Females. John I. Clark. Oxford University Press, 2000.

FURTHER READING

1860 1880 1920 1960 2000 2040

110

108

106

104

102

100

98

96

94

921900 1940

YearSOURCE: U.S. Census Bureau

Num

ber o

f Men

per

100

Wom

en in

the

U.S.

1980 2020 2060

Ages 20–44

Ages 20–44, projected

All ages

All ages, projectedEven sex ratio

RO

DG

ER

DO

YL

E