Wealth and Fertility (England, 1500-1879)

Source:
The Son Also Rises
Gregory Clark (2014)

How Universal is the Negative Correlation between Education and Fertility?

How Universal is the Negative Correlation between Education and Fertility?
Gerhard Meisenberg (2008)


Abstract

A negative correlation between education and fertility has been described with great regularity in modern societies. The present investigation examines the strength of this relationship with data from the  1990, 1995 and 2000 waves of the World Values Survey covering 78 countries with a combined sample size of up to 181,728 respondents. The negative correlation is present in nearly all countries, is stronger in females than males, is greater for educational level than for length of schooling, and is not mediated by personal wealth. It is strongest at relatively low levels of economic, social and cognitive development and becomes weaker in the most advanced societies. However, it is also less than maximal in the least developed countries. The relationship is strongest in Latin America and the Middle East, where the typical correlations for cohorts with completed fertility are -.31 for females and -.24 for males, and weakest in Protestant Europe, where average correlations are -.10 for females and -.01 for males. The negative relationship persists in the younger generation of advanced societies, who are reproducing under conditions of sub-replacement fertility.

An Association Between the Kinship and Fertility of Human Couples

An Association Between the Kinship and Fertility of Human Couples
Agnar Helgason et al.; 2008


Abstract

Previous studies have reported that related human couples tend to produce more children than unrelated couples but have been unable to determine whether this difference is biological or stems from socioeconomic variables. Our results, drawn from all known couples of the Icelandic population born between 1800 and 1965, show a significant positive association between kinship and fertility, with the greatest reproductive success observed for couples related at the level of third and fourth cousins. Owing to the relative socioeconomic homogeneity of Icelanders, and the observation of highly significant differences in the fertility of couples separated by very fine intervals of kinship, we conclude that this association is likely to have a biological basis.


See also: http://www.sciencemag.org/content/322/5908/1634.2.full.pdf 
(Comment on “An Association Between the Kinship and Fertility of Human Couples” - Rodrigo Labouriau and António Amorim; 2008)



[Thanks @ Tomás]

An Evolutionary Perspective on Human Fertility

An Evolutionary Perspective on Human Fertility
Kevin MacDonald; 1999


Abstract

This paper illustrates evolutionary approaches to population issues. Life history theory is a general theoretical framework that incorporates environmental influences, contextual influences, and heritable variation. In general, physically or psychologically stressful environments delay maturation and the onset of reproductive competence. Perceptions of scarcity also result in lower fertility by delaying reproduction or having fewer children—a phenomenon viewed as an adaptation to ancestral environments. The desire for upward social mobility is viewed as an evolved  motive disposition affecting fertility decisions. The opportunity for upward social mobility typically results in delaying reproduction and lowering fertility in the interest of increasing investment in children. Variation in life history strategies is also influenced by genetic variation, but genetic variation interacts with cultural shifts in the social control of sexual behavior. Finally, I discuss the effects of between-group competition for resources on population issues. Immigration policy and group differences in fertility influence political power within and between societies, often with explosive results. Demographic expansion has often been an instrument of ethnic competition and is an important source of conflict in the contemporary world.

Social Status & Reproductive Success

(full size: click at the image)




[Source: Sex, status, and reproductive success in the contemporary United States; Rosemary L Hopcroft; 2006]

Adult Temperament and Childbearing over the Life Course

Adult Temperament and Childbearing over the Life Course
Markus Jokela et al.; 2010


Abstract

Emerging evidence suggests that temperament may predict childbearing. We examined the association between four temperament traits (novelty seeking, harm avoidance, reward dependence and persistence of the Temperament and Character Inventory) and child-bearing over the life course in the population-based Cardiovascular Risk in Young Finns study (n 1⁄4 1535; 985 women, 550 men). Temperament was assessed when the participants were aged 20–35 and fertility history from adolescence to adulthood was reported by the participants at age 30–45. Discrete-time survival analysis modelling indicated that high childbearing probability was predicted by low novelty seeking (standardized OR 1⁄4 0.92; 95% confidence interval 0.88–0.97), low harm avoidance (OR 1⁄4 0.90; 0.85–0.95), high reward dependence (OR 1⁄4 1.09; 1.03–1.15) and low persistence (OR 1⁄4 0.91; 0.87–0.96) with no sex differences or quadratic effects. These associations grew stronger with increase in numbers of children. The findings were substantially the same in a completely  prospective analysis. Adjusting for education did not influence the associations. Despite its negative association with overall childbearing, high novelty seeking increased the probability of having children in participants who were not living with a partner  (OR 1⁄4 1.29; 1.12–1.49). These data provide novel evidence for the role of temperament in influencing childbearing, and suggest possible weak natural selection of temperament traits in contemporary humans.

Association of adolescent obesity and lifetime nulliparity

Association of adolescent obesity and lifetime nulliparity – SWAN, the study of women's health across the nation

Alex J Polotzky et al., 2011

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2891509/


Abstract

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Objective

To evaluate whether adolescent obesity is associated with difficulties for becoming pregnant later in life.

Design

Cross-sectional analysis of baseline data from a longitudinal cohort

Setting

Multiethnic, community-based observational study of US women

Patient(s)

3154 midlife women

Main Outcome Measure(s)

Lifetime nulliparity and lifetime nulligravidity

Result(s)

527 women (16.7%) women had never delivered a baby. Participants were categorized by self-reported high school body mass index (BMI): underweight (< 18.5 kg/m²), normal (18.5 to 24.9 kg/m²), overweight (25-29.9 kg/m²), and obese (> 30 kg/m²). The prevalence of lifetime nulliparity increased progressively across the high school BMI categories: 12.7%, 16.7%, 19.2%, and 30.9%, respectively (p<0.001). Multivariable logistic regression analysis confirmed that women who were obese adolescents had significantly higher odds of remaining childless as compared to normal weight women (odds ratio [OR] 2.84, 95% confidence intervals [CI] 1.59 to 5.10) after adjusting for adult BMI, history of non-gestational amenorrhea, marital status, ethnicity, study site, and measures of socioeconomic status. Furthermore, adolescent obesity was associated with lifetime nulligravidity (OR 3.93, 95% CI 2.12 to 7.26).

Conclusion(s)

Adolescent obesity is associated with lifetime nulliparity and nulligravidity in midlife U.S. women.

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[There seems to be a connection between high sugar diets and obesity. Maybe these diets also cause a lowered fertility in women.] 

Do Siblings’ Fertility Decisions Influence Each Other?

Do Siblings’ Fertility Decisions Influence Each Other?

Alexia Prskawetz; 2010
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000038/


Abstract

Individuals’ fertility decisions are shaped not only by their own characteristics and life course paths but also by social interaction with others. However, in practice, it is difficult to disentangle the role of social interaction from other factors, such as individual and family background variables. We measure social interaction through the cross-sibling influences on fertility. Continuous-time hazard models are estimated separately for women’s first and second births. In addition to individual socioeconomic variables, demographic variables, and an unobserved factor specific to each sibling pair, siblings’ birth events and their timing enter as time-varying covariates. We use data from longitudinal population-wide Norwegian administrative registers. The data cover more than 110,000 sibling pairs and include the siblings’ fertility, education, income, and marital histories. Our results indicate that cross-sibling influences are relatively strong for the respondents’ first births but weak for the second parity transition.

Fertility and aging: do reproductive-aged Canadian women know what they need to know?

Fertility and aging: do reproductive-aged Canadian women know what they need to know? 

Karla L Bretherick et al.; 2010

Objective

Female fertility declines with age; however, women are increasingly delaying childbearing until later in their reproductive years. One of the factors that may contribute to this trend is a general lack of knowledge about the decline in fertility with age.

Result(s)

Although most women were aware that fertility declines with age, they significantly overestimated the chance of pregnancy at all ages and were not conscious of the steep rate of fertility decline.  [!!!] Surprisingly, women overestimated the chance of pregnancy loss at all ages, but did not generally identify a woman's age as the strongest risk factor for miscarriage.

Conclusion(s)

Education regarding the rate at which reproductive capacity declines with age is necessary to avoid unintended childlessness among female academics and professionals.

[A very important question: No they don't! ... and nobody cares.]

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see also: http://digressionality.blogspot.co.at/2012/01/effect-of-age-on-female-fertility.html

Socioeconomic Status, Education, and Reproduction in Modern Women: An Evolutionary Perspective

Socioeconomic Status, Education, and Reproduction in Modern Women: An Evolutionary Perspective
Susanne Huber et al., 2010
http://131.130.59.105:8080/3/anthro1/people/mfieder/publications/pdfs/4HUBERBOOKSTEINFIEDER_2010.pdf


Abstract

Although associations between status or resources and reproduction are positive in premodern societies and also in men in modern societies, in modern women the associations are typically negative. We investigated how the association between socioeconomic status and reproductive output varies with the source of status and resources, the woman’s education, and her age at reproductive onset (proxied by age at marriage). By using a large sample of US women, we examined the association between a woman’s reproductive output and her own and her husband’s income and education. Education, income, and age at marriage are negatively associated with a woman’s number of children and increase her chances of childlessness. Among the most highly educated two-thirds of the sample of women, husband’s income predicts the number of children. The association between a woman’s number of children and her husband’s income turns from positive to negative when her education and age at marriage is low (even though her mean offspring number rises at the same time). The association between a woman’s own income and her number of children is negative, regardless of education. Rather than maximizing the offspring number, these modern women seem to adjust investment in children based on their family size and resource availability. Striving for resources seems to be part of a modern female reproductive strategy—but, owing to costs of resource acquisition, especially higher education, it may lead to lower birthrates: a possible evolutionary explanation of the demographic transition, and a complement to the human capital theory of net reproductive output.

Physical attractiveness and reproductive success in humans: Evidence from the late 20th century United States

Physical attractiveness and reproductive success in humans: Evidence from the late 20^th century United States

Markus Jokela, 2009
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000557/

Abstract

Physical attractiveness has been associated with mating behavior, but its role in reproductive success of contemporary humans has received surprisingly little attention. In the Wisconsin Longitudinal Study (1244 women, 997 men born between 1937 and 1940) we examined whether attractiveness assessed from photographs taken at age ~18 predicted the number of biological children at age 53–56. In women, attractiveness predicted higher reproductive success in a nonlinear fashion, so that attractive (second highest quartile) women had 16% and very attractive (highest quartile) women 6% more children than their less attractive counterparts. In men, there was a threshold effect so that men in the lowest attractiveness quartile had 13% fewer children than others who did not differ from each other in the average number of children. These associations were partly but not completely accounted for by attractive participants’ increased marriage probability. A linear regression analysis indicated relatively weak directional selection gradient for attractiveness (β=0.06 in women, β=0.07 in men). These findings indicate that physical attractiveness may be associated with reproductive success in humans living in industrialized settings.

Serial monogamy increases reproductive success in men but not in women

Serial monogamy increases reproductive success in men but not in women

Markus Jokela et al., 2010

http://beheco.oxfordjournals.org/content/21/5/906.full

Abstract

Evolutionary theory predicts that males seek more sexual partners than females because of their higher fitness benefits from such a reproductive strategy. Accordingly, variance in numbers of partners and offspring is expected to be greater and association between mating and reproductive success to be stronger in males. Studies testing key predictions of this hypothesis in humans are lacking. Using data of 3700 men and 4010 women living in contemporary United States, we examined sex differences in the variance of number of spouses and offspring and in the association between spouse number and number of offspring. The results suggested a stronger selective advantage of serial monogamy in men than in women. Variance in spouse and offspring number was, respectively, 5% and 10% higher in men. In addition, the association between mating and reproductive success was stronger in men, so that men with 3 or more consecutive spouses had 19% more children than men with only spouse, whereas spouse number beyond the first partner was not associated with number of children in women. When the sample was stratified by ethnic group, the sex differences were stronger among Black and Hispanic participants than among White participants.

Birth-Cohort Effects in the Association Between Personality and Fertility:

Birth-Cohort Effects in the Association Between Personality and Fertility
Markus Jokela, 2012


Abstract

The present study investigated whether associations between individuals’ personality traits and whether they have children have been modified by birth-cohort effects in the 20th-century United States. Participants were from the Midlife Development in the United States study (n = 6,259) and the Wisconsin Longitudinal Study (n = 3,994) and were born between 1914 and 1974. Data on personality traits of the Five Factor model and fertility history were collected in adulthood. Higher levels of openness to experience in both sexes and higher levels of conscientiousness in women were associated with lower fertility, and these associations strengthened linearly as birth cohorts became younger. In the total sample, high extraversion, low neuroticism, and women’s high agreeableness were associated with high fertility rate, but there were no systematic cohort effects. The fertility decisions of people with certain personality traits may be influenced by prevailing societal and cultural circumstances.
[It would be interesting to know how strong these correlations and cohort effects are. ]