Original articleSex, status, and reproductive success in the contemporary United States
Introduction
In most animal populations, status or social rank is positively related to reproductive success (Ellis, 1995, Low et al., 2002, Strier, 2003, Voland, 1998). There is much evidence that the same relationship between status and reproductive success also holds in preindustrial human populations, especially for males (see Table 1).
In modern human populations, the demographic transition and the availability of effective contraception appear to have severed the link between status and reproductive success, as previous studies suggest that high-status individuals have somewhat fewer offspring than do low-status individuals (Dickemann, 1993, Kaplan et al., 1995, Kaplan et al., 2002, Low et al., 2002, Morgan, 1996, Morgan, 2003, Pérusse, 1993, Potts, 1997, van den Berghe & Whitmeyer, 1990, Vining, 1986). Empirical studies suggest that fewer children, even if they are high quality, mean fewer genetic descendants on average (Kaplan et al., 1995, Mueller, 2001). Many of the criticisms of the use of evolutionary biology in the social sciences take this “central theoretical problem of sociobiology” as the centerpiece of their assertion that evolutionary biology cannot explain the behavior of contemporary humans (Vining, 1986), claiming that human reproductive behavior is a product of social learning alone.
However, demographic studies of fertility use census or other data that only report female fertility or the number of children in a household (Greene & Biddlecom, 2000, Kaplan & Hill, 1986). Other studies use social survey data that do not distinguish between respondents' adopted, step, and biological children. Such studies do not fully measure male fertility, where the variance in reproductive success is predicted to be highest (Trivers, 1972, Trivers & Willard, 1973). There is evidence that male status as measured by wealth (Essock-Vitale, 1984, Vining, 1986) and height (Mueller & Mazur, 2001, Pawlowski et al., 2000) does promote reproductive success. These outcomes occur even given legally mandated monogamy and disproportionate female control over fertility decisions (Beckman et al., 1983, Kohler et al., 1999, Sorenson, 1989) because high-status males can achieve higher reproductive status through a series of marriages and/or families (Forsberg & Tullberg, 1995, Mueller & Mazur, 2001).
Here, I reexamine the relationship between status and reproductive success by measuring fertility as the number of biological children claimed by a probability sample of both men and women. This is the first such analysis for a modern, developed society (other analyses used convenience or snowball samples, e.g., Kaplan et al., 1995, Pawlowski et al., 2000, Pérusse, 1993, Mueller, 2001, Mueller & Mazur, 2001).
Some theorists contend that even if contemporary achieved fertility does not maximize reproductive success, our preferences and behaviors regarding fertility would promote reproductive success if not for contraception (Bongaarts, 1993, Boone & Kessler, 1999, Buss, 1999, Carey & Lopreato, 1995, Cosmides et al., 1992, Kaplan, 1994, Kaplan, 1996, Kaplan et al., 2002, Morgan & King, 2001, Potts, 1997, Rogers, 1995, Turke, 1989). For example, Pérusse (1993) found that although high-status males did not have greater achieved fertility than do low-status males, as measured by the number of children, they did have greater potential for fertility as estimated by copulation frequency (see also Kanazawa, 2003).
Furthermore, there appear to be evolved sex differences in mate preferences (Buss, 1989, Buss & Barnes, 1986, Buss & Schmitt, 1993, Buunk et al., 2001, Gangestad & Simpson, 2000, Oppenheimer, 2000), including a general female preference for equal or higher-status males as mates, and a general male preference for younger mates (Buss, 1989, Buss & Barnes, 1986, Buunk et al., 2001, Ellis, 2001, Kenrick & Keefe, 1992, Wiederman, 1993). The operation of these preferences over time leads to a shrinking pool of possible mates for high-status females and an expanding pool of possible mates for high-status males. In contrast, low-status females should find more available mates than low-status males would (Trivers, 1972, Trivers & Willard, 1973).
To analyze the relationship between status and fertility (both potential and achieved) and the interaction between sex and status in its effect on fertility, I tested the following hypotheses: Hypothesis 1 The relationship between individual status and potential fertility is positive. Hypothesis 2 The relationship between individual status and achieved fertility is positive. Hypothesis 3 Sex and status interact in their effects on potential fertility: The rate of increase of potential fertility with increasing status is greater for males than for females. Hypothesis 4 Sex and status interact in their effects on achieved fertility: The rate of increase of achieved fertility with increasing status is greater for males than for females.
Section snippets
Methods
I test these hypotheses with pooled data from the 1989 through 2000 General Social Surveys (GSS) conducted at the National Opinion Research Center (NORC) at the University of Chicago (Davis & Smith, 1998). Each survey is an independently drawn, multistage probability sample of noninstitutionalized, English-speaking persons age 18 or over, living in the United States. Not all variables are available for all years of the GSS; hence, depending on the variables used, some subset of one or more of
Frequency of sex
Table 3 gives the results of the ordered probit model of reported sex frequency to test Hypotheses 1 and 3. Age and Age2 are controlled. The main effect of sex is significant and positive and should be interpreted as the effect for males with less than a graduate degree (i.e., when grad=0) compared with females with less than a graduate degree. The coefficients on the dummy variables for highest degree attained for high school diploma and junior college diploma are both negative and significant
Discussion
Consistent with previous studies, the results presented here show that social status measured in the traditional ways (occupational prestige, socioeconomic status, and education) has a null or negative effect on both potential and achieved fertility for both men and women in the contemporary United States. These findings replicate previous findings from research on both sexual behavior (see Rushton & Bogaert, 1988) and achieved fertility (Morgan, 1996, Morgan, 2003, Vining, 1986). However, the
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