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The hypothesis that father absence during childhood, as well as other forms of childhood psychosocial stress, might influence the timing of sexual maturity and adult reproductive behaviors has been the focus of considerable research. However, the majority of studies that have examined this prediction have used samples of women of European descent living in industrialized, low-fertility nations. This paper tests the father-absence hypothesis using the Cape Area Panel Study (CAPS), which samples young adults in Cape Town, South Africa. The sample contains multiple racial groups (blacks, coloureds [mixed race], and whites) and includes both males and females. Dependent variables include age at menarche, age at first sexual intercourse, and age at first pregnancy. Childhood stress is measured by father absence by age six (either never lived with father or lived with father some but not all years) and an index of childhood exposure to violence (measuring threatened or actual verbal or physical abuse). The hypothesis received no support for effect on age at menarche but was supported for age at first sex and first pregnancy. The model showed stronger support for coloureds and whites than blacks and had no predictive power at all for black males.

SummaryTubal ligation is the modal form of family planning among American women aged 30 and older. As the preference for tubal ligation over cheaper, lower risk and more reliable methods, such as vasectomy, has puzzled experts, a theoretical approach that explains this preference would be useful. The present study investigates the high prevalence of voluntary sterilization among American women from the perspective of life history theory, arguing that the trade-offs between investing in current and future offspring will favour tubal ligation when women cannot obtain reliable male commitment to future parental investment. Data came from the National Survey of Fertility Barriers (NSFB), a nationally representative survey of 4712 American women aged 25–45 conducted between 2004 and 2007. Four novel predictions of the prevalence of tubal ligation, drawn from life history theory, were developed and tested: 1) it is most common among unpartnered women with children, and least common among married women with children; 2) it is negatively correlated with age at first birth; 3) it is least common among highly educated women without children, and most common among less educated women with children; and 4) among women with two or more children, it is positively correlated with lifetime number of long-term partners. These predictions were tested using multivariate regression analysis. The first prediction was not supported: women with children were more likely to be sterilized, regardless of their marital status. The other three predictions were all supported by the data. The results suggest that trade-offs influence women’s decisions to undergo voluntary sterilization. Women are most likely to opt for tubal ligation when the costs of an additional child will impinge on their ability to invest in existing offspring, especially in the context of reduced male commitment.

Independent of ecology, subsistence strategy, social complexity, or other aspects of socioecology, the altricial nature of young humans requires mothers to have help raising their offspring. What seems to be context-dependent, however, is who the helpers are, how they invest, and what the impacts of that investment are. In a series of papers that focus on parental and alloparental investment across five populations, this special issue of Human Nature uses evolutionary theory to examine how socioecological context influences modes of direct parental investment among the boat-dwelling Shodagor of Bangladesh (Starkweather), modes of indirect paternal investment in the modern United States (Anderson), and the biological outcome of paternal investment for men in Jamaica (Gray et al.), as well as direct alloparental investment among village Bangladeshis (Perry) and indirect alloparental investment in breastfeeding practices in the United States (Cisco).

The establishment of a legal father for children of unmarried parents reflects both high paternity confidence and male willingness to commit to paternal investment. Whether an unmarried man voluntarily acknowledges paternity after a child is born has important consequences for both the mother and child. This paper brings to bear a life history perspective on paternity establishment, noting that men face trade-offs between mating and parental effort and that women will adjust their investment in children based on expected male investment. I predict that paternity establishment will be more likely when the mother has high socioeconomic status, when maternal health is good, and when the child is male, low parity, or a singleton (versus multiple) birth. I further predict that establishment of paternity will be associated with increased maternal investment in offspring, resulting in healthier babies with higher birthweights who are more likely to be breastfed. These predictions are tested using data on 5.4 million births in the United States from 2009 through 2013. Overall the results are consistent with the hypothesis that the trade-offs men face between reproductive and parental investment influence whether men voluntarily acknowledge paternity when a child is born.

Although the vulnerability of young people to HIV/AIDS continues to be a serious concern in South Africa, no research has used a representative sample of South African youth to examine whether individual HIV risk perceptions change over time and, if they do, what factors are associated with change. Using data from the Cape Area Panel Study, a multi-racial, longitudinal study of youth and their households, this study examined whether youth change their HIV risk perceptions over a four-year period and whether sexual behaviors, knowing someone with HIV, gender and race are associated with any change. Overall, changes in HIV risk perceptions tend to be small. As predicted, sexual activity is associated with increases in risk perceptions. Contrary to predictions, condom use at last sex is associated with increases in risk perceptions and knowing someone with HIV is associated with decreases in risk perceptions. In addition, there is variation by gender and by race in the factors associated with change in risk perceptions. This study serves as an initial examination of change in the HIV risk perceptions of South African youth; further investigation of their HIV risk perceptions over time is needed.Keywords: HIV/AIDS, Risk Perceptions, First Sex1. INTRODUCTIONIn recent years, hopeful signs regarding the HIV/AIDS epidemic among young people in South Africa have emerged. HIV prevalence among young people in South Africa appears to be stabilizing. For 15- 24 year-olds, national HIV prevalence rates were estimated at 9.3% in 2002, 10.3% in 2005 and 8.7% in 2008, the most recent year for which national HIV prevalence data are available (Shisana and Simbayi, 2002; Shisana, 2009). HIV incidence appears to have declined in recent years among teenage males and females and 20-24 year-old females (Fraser-Hurt et al., 2011), which has been attributed to increases in condom use among young people (Shisana, 2009).In spite of these encouraging trends, the vulnerability of young people to HIV/AIDS continues to be a serious concern in South Africa. HIV transmission largely occurs through heterosexual intercourse in South Africa and portions of the youth population continue to engage in sexual behaviors that place them at risk of HIV infection (Shisana, 2009; Fraser-Hurt et al., 2011). Risk perceptions are a central component of many models of health behavior (for a recent review, Aiken et al., 2012). These models give rise to the behavior motivation hypothesis, or the prediction that individuals who perceive themselves to be at risk of a disease will engage in behaviors known to prevent the disease (Brewer et al., 2004). Numerous studies of disease have tested the behavior motivation hypothesis; fewer studies have tested the risk reappraisal hypothesis, or the prediction that taking an action believed to reduce risk of a disease will lower self-perceived risk for the disease (Brewer et al., 2004). Research to date (to the best of our knowledge) has not specifically considered whether the HIV risk perceptions of South African youth change over time and if they do, what factors are associated with change. This study uses data from the Cape Area Panel Study (CAPS), a longitudinal study of youth and their households from Cape Town, South Africa, to examine whether HIV risk perceptions change over a four-year period and whether sexual behaviors, knowing someone with HIV, race and gender are associated with any change.1.1. HIV Risk PerceptionsA number of studies have found that young South Africans often perceive their risk of HIV infection to be low, even if they engage in sexual risk behaviors (Macintyre et al., 2004; Anderson et al., 2007; Kenyon et al., 2010a; Fraser-Hurt et al., 2011), which may reflect youthful optimism and feelings of invulnerability (Moore and Rosenthal, 1991; Macintyre et al., 2004). (For studies finding that young South Africans have at least moderate levels of knowledge about the sexual transmission of HIV, (Anderson and Beutel, 2007; Shisana, 2009; Fraser- Hurt et al. …

Objectives To examine the relationships between prepregnancy diabetes mellitus (DM), gestational diabetes mellitus (GDM), and prepregnancy body mass index, with several adverse birth outcomes: preterm delivery (PTB), low birthweight (LBW), and macrosomia, comparing American Indians and Alaska Natives (AI/AN) with other race/ethnic groups. Methods The sample includes 5,193,386 singleton US first births from 2009-2013. Logistic regression is used to calculate adjusted odds ratios controlling for calendar year, maternal age, education, marital status, Kotelchuck prenatal care index, and child's sex. Results AI/AN have higher rates of diabetes than all other groups, and higher rates of overweight and obesity than whites or Hispanics. Neither overweight nor obesity predict PTB for AI/AN, in contrast to other groups, while diabetes predicts increased odds of PTB for all groups. Being overweight predicts reduced odds of LBW for all groups, but obesity is not predictive of LBW for AI/AN. Diabetes status also does not predict LBW for AI/AN; for other groups, LBW is more likely for women with DM or GDM. Overweight, obesity, DM, and GDM all predict higher odds of macrosomia for all race/ethnic groups. Conclusions for Practice Controlling diabetes in pregnancy, as well as prepregnancy weight gain, may help decrease preterm birth and macrosomia among AI/AN.

Due to tradeoffs between mating and parental effort, men who pay child support to children from previous unions should be less likely to have subsequent children or to remarry than men who do not pay child support. I evaluate this prediction using data from the Panel Study of Income Dynamics (PSID), a nationally representative sample of American households. As predicted, child support payment is associated with lower probability of subsequent birth. However, the prediction was not met for marriage: men who paid child support were more, rather than less, likely to remarry. One interpretation of this result is that child support payment is an honest signal of men's willingness to commit to parental investment: by continuing to pay child support, men signal to prospective mates that they are good investors. Child support may thus function to some extent as mating effort, by attracting subsequent long-term mates.

Life history theory predicts that greater extrinsic mortality will lead to earlier and higher fertility. To test this prediction, I examine the relationship between life expectancy at birth and several proxies for life history traits (ages at first sex and first marriage, total fertility rate, and ideal number of children), measured for both men and women. Data on sexual behaviors come from the Demographic and Health Surveys (DHS). Two separate samples are analyzed: a cross-sectional sample of 62 countries and a panel sample that includes multiple cross-sectional panels from 48 countries. Multivariate regression analysis is used to control for potential confounding variables. The results provide only partial support for the predictions, with greater support among women than men. However, the prediction is not supported in sub-Saharan African countries, most likely owing to the nonequilibrium conditions observed in sub-Saharan Africa with respect to life expectancy. The applicability of the model to understanding HIV/AIDS risk behaviors is discussed.

There is high demand for care among the Hispanic population in states along the U.S.-Mexico border. The objective is to describe the standard of care received by people living with HIV/AIDS (PLWH/A) at enrollment into one of five Special Projects of National Significance (SPNS) Sites located along the U.S.-Mexico border. This cross-sectional study describes the presence of opportunistic infections (OIs), AIDS status and two types of standard of care received by 707 PLWH/A participating in SPNS. Patients receiving care through SPNS in one of the five sites between June 1, 2002 and December 31, 2003 were invited to participate to the medical chart review component of the study. The association between sociodemographic variables and the prevalence of OIs and AIDS at enrollment was estimated using multivariate hierarchical logistic models. More than one quarter of the 707 participants had at least one OI recorded and 58% of new and 60% of existing patients had AIDS at enrollment in SPNS. The association between being Hispanic and having higher prevalence of OI and AIDS at entry varied by SPNS site. Standard of care was well followed overall. This is the first study describing HIV stage and OI prevalences and standard of care in PLWH/A in all U.S.-Mexico bordering states. Being of Hispanic ethnicity may not fully explain discrepancy in access to care along the border.

South Africa, a country that is highly stratified by race, is an important location for studying the relationship between race and educational expectations. Using a longitudinal data set, we examine the educational expectations of black (African), colored (mixed race), and white (European ancestry) parents and children in Cape Town, South Africa. We find that parents and children have high educational expectations regardless of race, but black parents and children have higher educational expectations than coloreds and whites once socioeconomic and other factors are controlled. We also find that parents' and children's expectations tend to agree more and are more closely correlated among coloreds and whites than blacks. We test two explanations for the educational expectations of parents and children, finding more support for the status attainment perspective among coloreds and whites than blacks and support for the family social capital perspective among blacks and coloreds only.

Educational expectations, in particular the relationship between race/ ethnicity and educational expectations, have been understudied in less developed countries. We use data from the Cape Area Panel Study (CAPS) to examine the educational expectations of black (African), coloured (mixed race), and white (European ancestry) youth in Cape Town, South Africa. The educational expectations of all three racial groups are high, although coloured youth are less likely than black and white youth to expect to complete postsecondary or postgraduate schooling. Supporting research on educational expectations in the United States and other more developed countries, our findings indicate that socioeconomic status and academic performance matter for educational expectations in South Africa, although their importance varies by racial group. In contrast to U.S. studies that have found effects of family composition for whites only, we found virtually no effects of family composition on the educational expectations of whites or nonwhites. Our findings suggest possible similarities and differences across social contexts in the processes shaping the educational expectations of youth from disadvantaged groups. Because of their potential to influence educational outcomes, educational expectations have been of considerable interest to sociologists. A great deal of research has examined educational expectations in the United States and other more developed countries (e.g., Buchmann and Dalton 2002; Cheng and Starks 2002; Hao and Bonstead-Bruns 1998; Hauser, Tsai, and Sewell 1983; Looker and Pineo 1983; Marjoribanks 2002; Sewell, Haller, and Portes 1969). Relatively few studies have investigated educational expectations in less developed countries (e.g., Adams, Wasikhongo, and Nahemow 1987; Forste, Heaton, and Haas 2004; Moller 1995; Post 1990), particularly the relationship between race/ethnicity and educational expectations. How educational expectations are formed in parts of the world with social structures that may differ from those in the United States and other more developed countries is not well understood. South Africa presents an ideal location for considering how context may influence educational expectations, as a number of social and economic features distinguish it from the United States and other more developed countries. One is the tremendous economic stratification of the country. Wage inequality in South Africa is among the highest in the world, and unemployment rates are as high as 40% (Burger and Woolard 2005; Kingdon and Knight 2001; Klasen 1997; Leibbrandt, Woolard, and Woolard 2000). As a result, there is tremendous variation in access to educational capital, which may influence educational expectations. second is the nature of racial stratification in South Africa: under apartheid (the policy of extreme racial segregation practiced until the early 1990s), individuals were placed into one of three groups on the basis of race-an advantaged group composed of whites (those of European ancestry), a moderately disadvantaged group consisting of both coloureds (those of mixed race) and Asians (mostly from India), and a severely disadvantaged group made up of blacks (Africans) (e.g., Klasen 1997; Mwabu and Schultz 1996; Thomas 1996). Although de jure discrimination ended with the dismantling of apartheid, racial inequality persists in South Africa (e.g., Burgard and Treiman 2006; Burger and Woolard 2005; Charasse-Pouele" and Fournier 2006; Lestrade-Jefferis 2002). By studying educational expectations in a country with a clearly defined racial status hierarchy, we may improve our understanding of the relationship between race and educational expectations. Third, South Africa provides a different schooling context in which to examine educational expectations. For example, school fees (tuition) are generally charged for school enrollment, even for primary and secondary education. Last, dramatic social changes have occurred in South Africa over the past fifteen years. …

HIV/AIDS knowledge is an important component of HIV/AIDS risk prevention strategies that may influence engagement in high risk behavior. This paper examines HIV/AIDS prevention knowledge among a representative sample of 4,174 youth living in Cape Town, South Africa. Data come from the Cape Area Panel Study (CAPS), and include black, coloured, and white respondents ages 14-22. Using an open-ended question, respondents were asked to name ways people can protect themselves from HIV/AIDS infection. Nearly everyone could name at least one method of preventing HIV infection, and respondents named two methods on average. Condoms, abstinence, and limiting the number of sexual partners/having only one sexual partner were the most frequently named prevention methods. Multivariate analysis was used to analyze correlates of specific forms of HIV/AIDS prevention, as well as the total number of prevention methods named by each respondent. Having had sex, highest grade completed, and race were the most commonly significant correlates across models. Race interaction terms were also significant, suggesting that the significance of HIV/AIDS knowledge correlates varies across racial groups. Overall, the results suggest that more depth of knowledge about HIV/AIDS is needed among South African youth to ensure proper protection from the disease, and that HIV/AIDS education might be more successful if tailored to specific racial/ethnic groups.

Using a sample of men living in Albuquerque, NM, we examined the relationship between paternity confidence and men's investment in children. In humans, men may reduce their investment in a child in two ways: indirectly, by ending their relationship with the child's mother and ceasing to cohabit with the child (e.g., divorce), and directly, by allocating less time and fewer resources to the child. In this article, we tested two hypotheses regarding the effect of paternity confidence on investment in children: (1) men will be more likely to divorce women if they suspect or are sure that they are not the father of their wife's child, and (2) controlling for divorce, men will reduce direct investments in low paternity confidence children relative to high paternity confidence children. The first hypothesis was supported by the data. The second hypothesis was supported for two out of three measures of paternal investment we examined; low paternity confidence reduces the time men spend with a child in a group with other children or adults, and it reduces extensive involvement with the child's educational progress; there was no effect of paternity confidence on the amount of time men spend with children in one-on-one interactions. We also examined the effects of unstated paternity confidence (e.g., when men decline to answer the question) on divorce and paternal investment. Overall, the results suggested that paternity confidence plays an important role in shaping men's relationships with women and with their putative genetic children.

The purpose of this study is to provide a description of personal lifestyles and demographic characteristics of 1,200 HIV seropositive individuals who volunteered to participate in a Health Resources and Services Administration (HRSA), Special Projects of National Significance (SPNS) Initiative conducted in five U.S. demonstration projects located along the U.S.-Mexico border between 2001 and 2004. The results show that HIV/AIDS patients receiving care along the U.S.-Mexico border are predominantly Hispanics (81%) and men who have sex with men (56%). In general, SPNS participants appear to be sociodemographically similar to the general HIV/AIDS population in the U.S. with a few noted exceptions such as age, labor force participation, and variations in mode of transmission by age and gender.

Investment in children is examined using a nationally representative sample of 11,211 black (African) households in South Africa. I randomly selected one child from each household in the sample and calculated the average genetic relatedness of the other household members to the focal child. Using multivariate statistical analysis to control for background variables such as age and sex of child, household size, and socioeconomic status, I examine whether the coefficient of relatedness predicts greater household expenditures on food, on health care, and on children's clothing. I also test whether relatedness is associated with health and schooling outcomes. The results are consistent with an inclusive fitness model: Households invest more in children who are more closely related. Two exceptions were found: in rural areas, genetic relatedness was negatively associated with money spent on food and on health care. Explanations for these results are discussed.

The stepfather relationship provides a source of potential conflict in remarriage families, because the mother and partner may have different interests in the well-being of children from a prior union. Using three different theoretical perspectives—biology, sociology, and selection—this paper examines the engagement, availability, participation, and warmth of residential fathers in married biological parent, unmarried biological parent, married stepparent, and cohabiting father families. The data come from 2,531 children and their parents who were interviewed during the 1997 wave of the Child Development Supplement to the Panel Study of Income Dynamics. Biology explains less of father involvement than anticipated once differences between fathers are controlled. Marriage continues to differentiate paternal investment levels, as do age of child and financial responsibility to nonresidential children.

This paper provides an overview of evidence on education in South Africa provided by household survey data, with a particular focus on large national surveys such as the 1993 South African Living Standards Survey and the annual October Household Survey. These surveys indicate that racial gaps in schooling persist in South Africa, although they have declined steadily over time. There is essentially no gender gap in schooling, however, with almost identical schooling outcomes for men and women in all racial groups. The racial gap in schooling can be largely attributed to a high rate of grade repetition for Africans, with only small differences in enrollment rates across racial groups. School quality has an important effect on both grade attainment and adult economic outcomes, and is clearly an important component of the racial gap in schooling. Survey data clearly demonstrate a large effect of schooling on earnings beginning in late primary years, with a higher rate of return to schooling for Africans than for whites. Datasets Used October Household Survey (OHS): South Africa, 1995 Schooling outcomes in South Africa

This paper presents an analysis of the characteristics of men who become stepfathers, and their subsequent fertility patterns and lifetime reproductive success. Because women who already have children are ranked lower in the marriage market than women without children, men who marry women with children (e.g., stepfathers) are likely to have lower rankings in the marriage market as well. Using retrospective fertility and marital histories from the Panel Study of Income Dynamics (PSID), I show that men who become stepfathers have lower levels of education, less income, and are more likely to have been divorced before and to already have children, all characteristics that lower their rankings in the marriage market. Men with one or two stepchildren are just as likely to have children within a marriage as non-stepfathers, although men with three stepchildren show decreased fertility. Among men age 45 and older, stepfathers have lower lifetime fertility than non-stepfathers, although the difference disappears when men's age at first marriage is controlled for. Additionally, stepfathers have significantly higher fertility than men who never marry. The results suggest that some men become stepfathers to procure mates and fertility benefits that they would otherwise have been unlikely to obtain; for these men, raising other men's children serves as a form of mating effort.

In this article we present a biosocial model of human male parental care that allows relationship (mating) effort to influence male parental allocations. The model recognizes four classes of relationships between men and the children they parent: genetic offspring of current mates (combined relationship and parental effort), genetic offspring of previous mates (parental effort solely), step offspring of current mates (relationship effort solely), and stepchildren of previous mates (essentially no expected investment). We test the model using data on parental investment collected from 340 Xhosa high school students in Cape Town, South Africa. Six measures of paternal investment are examined: the amount of money men spent on students for school, clothing, and miscellaneous expenditures, respectively, and how often men spent time with children, helped them with their homework, or spoke English with them. The tests provide support for the roles of both parental and relationship effort in influencing parental care: men invest significantly more in their genetic offspring and in the children of their current mates. We also examine several proximate influences on parental care, specifically the age and sex of the child, and the percentage of the child's life the father figure coresided with him or her.

We present a biosocial model of human male parental care that allows male parental allocations to be influenced not only by changes in the fitness (welfare) of the recipient offspring, but also by their effects on the man's relationship with the child's mother. The model recognizes four classes of relationships between males and the children they parent: genetic offspring of current mates (combined relationship and parental effort), genetic offspring of previous mates (parental effort solely), step offspring of current mates (relationship effort solely), and stepchildren of previous mates (essentially no expected investment). We test the model using data on parental investments collected from adult males living in Albuquerque, New Mexico, U.S.A. Four measures of paternal investment are examined: the probability that a child attends college (2,191 offspring), the probability that a child who attends college receives money for it ( N = 1,212), current financial expenditures on children ( N = 635), and the amount of time per week that men spend with children ages 5 to 12 years ( N = 2,589). The tests are consistent with a role for relationship effort in parental care: men invest more in the children of their current mates, even when coresidence with offspring is not a confounder.

HIV prevalence is high among South African youth. Health behavior models posit that the perceived level of risk of HIV infection is associated with the level of HIV risk behavior; however, there has been limited research in Sub-Saharan Africa on factors associated with perceived risk or on the relationship between perceived risk and risk behaviors.Longitudinal data collected in 2002 and 2005 from 3,017 black, colored and white youth in Cape Town, South Africa, were analyzed using multivariate regression to examine whether a reciprocal relationship exists between sexual experience and perceived HIV risk. Independent variables taken from the 2002 survey were used to predict dependent variables taken from the 2005 survey.In 2005, most youth (82% of males and 83% of females) viewed themselves as being at no or small risk of HIV infection. A reciprocal relationship in which higher perceived HIV risk was associated with a delay in sexual debut (odds ratio, 0.8) and sexual experience was associated with higher perceived risk (1.4) was found for females, but not for males. Knowing someone who had died of AIDS was associated with sexual debut and with an elevated perceived HIV risk among females (1.7 and 1.3, respectively). The associations between race and perceived risk of HIV infection varied by gender.HIV/AIDS education and prevention programs should consider more carefully how gender and race may intersect to influence risk perceptions and risk behaviors. In addition, possible reciprocal relationships between risk behaviors and risk perceptions should be considered in education and intervention programs.

We examine the demographic correlates of paternity confidence, or men's assessment of the likelihood that they are the genetic father of a particular child. Evolutionary theory predicts that men will provide less parental investment for putative genetic offspring who are unlikely to be their actual offspring, but confidence of paternity has not been as extensively examined as its importance would merit. Using self-reported data on paternity confidence in 3,360 pregnancies reported by men living in Albuquerque, New Mexico, we find that low paternity confidence is more common among unmarried couples and for unplanned pregnancies. We also find that men are more likely not to state paternity confidence (i.e., they refuse to answer the question) if a pregnancy is unplanned. We additionally examine the pregnancy outcomes associated with confidence of paternity. We find that low paternity confidence pregnancies are significantly more likely to be aborted, and pregnancies for which paternity confidence is unstated are more likely to be aborted or to miscarry. Both abortion and miscarriage are associated with unmarried couples, with unplanned pregnancies, and with couples who have fewer children together.

Life history theory postulates tradeoffs of current versus future reproduction; in both developed and developing nations today, women face evolutionarily novel versions of these tradeoffs. Here we use a nonlinear dynamic model to explore: [1] the general issues of tradeoffs of education, work, and current fertility; [2] some specific examples (e.g., what increase in fertility will compensate for particular delays of age at first birth under given conditions). Finally, we model a largely unrecognized issue. Demographic transitions of the past have been characterized by decreases in fertility accompanied by (sometimes quite large) increases in per capita investment in offspring. The Rio Conference and its followup highlighted the conflicts between low-fertility, high-consumption, versus highfertility, lower consumption strategies — yet we have few ways to make testable predictions about future conflicts. We explore outcomes when impending resource constraints differentially affect short-generation-time-strategists, versus delayed-reproduction-resource-acquirers. The conditions favoring delayed fertility with resource accumulation are highly constrained; under almost all conditions reproduction in the early 20s leads to the greatest lineage success for women in the models.

This paper draws on evolutionary life history theory to examine nonmarital births in the context of women’s ability to secure male parental investment for their offspring. While nonmarital births are usually defined with respect to marital status the day of parturition, we adopt a more nuanced approach that corresponds to men’s willingness to commit to family obligations. Our approach distinguishes between marriages preceding pregnancy, marriages occurring between pregnancy and birth, marriages immediately following birth, and births that are not followed by marriage to the child’s father. Using retrospective marital and reproductive histories from the Panel Study of Income Dynamics (PSID), we observe a range in women’s life history outcomes (fertility and marital measure) corresponding to this range in male commitment around the time of first birth. Self-selection biases are not examined in this analysis, although their implications are discussed.

Life history theory postulates tradeoffs of current versus future reproduction; today women face evolutionarily novel versions of these tradeoffs. Optimal age at first birth is the result of tradeoffs in fertility and mortality; ceteris paribus, early reproduction is advantageous. Yet modern women in developed nations experience relatively late first births; they appear to be trading off socioeconomic status and the paths to raised SES, education and work, against early fertility. Here, [1] using delineating parameter values drawn from data in the literature, we model these tradeoffs to determine how much socioeconomic advantage will compensate for delayed first births and lower lifetime fertility; and [2] we examine the effects of work and education on women's lifetime and age-specific fertility using data from seven cohorts in the Panel Study of Income Dynamics (PSID).

The large human brain, the long period of juvenile dependence, long life span, and male support of reproduction are the co-evolutionary result of the human niche based on skill-in- tensive techniques of resource accrual. The regulation of fertility under traditional conditions is based upon a co-evolved psychology and physiology where adjustments of investment in offspring depend upon the returns to skill and mortality hazards. When all wealth is somatic, the hormonal system controlling ovulation and implantation translates income into genetic descendants. In modern society the existence of extra-somatic wealth is a critical condition to which our evolved proximate physio- logical mechanisms do not respond. However, psychological mechanisms regulating parental in- vestment in offspring quality may lead to greater and greater investment in own and offspring education, a smaller desired family size, a delay in the onset of reproduction, and a reduction in the total numbers of offspring produced. This delay in reproduction can cause many individuals to pro- duce fewer children than desired because fecundity falls during the reproductive part of the life course. As more individuals in a society follow this pattern, more will fail to reach their desired family size. At the same time the effective use of birth control decreases the numbers of families producing more children than desired. Below replacement fertility can result. Predictions from this model were tested using data from the National Survey of Families and Households and the Albuquerque Men study. Am. J. Hum. Biol. 14:233-256, 2002. 2002 Wiley-Liss, Inc