Cross‐Sectional and Longitudinal Associations between Body Mass Index and Marriage‐Related Factors

Objective: To assess the relationship between marriage and obesity. Research Methods and Procedures: Cross‐sectional and longitudinal associations were examined between participant body mass index (BMI), spouse BMI, and participant diet and exercise habits. Results: Spouse and participant BMI and BMI changes over 2 years were significantly associated. Participant BMI was associated with higher consumption of calorie‐dense foods and lower frequency of physical activity. Participants’ eating and exercise habits were only weakly related to spouse BMI. BMI did not predict the likelihood of marriage or divorce. However, marriage was associated with a significant 2‐year weight gain and divorce with a significant 2‐year weight loss. Discussion: The results suggest that spouse similarity in BMI is at least partly due to shared environment. The observed effects of marriage and divorce on weight may be due to the influence of marriage on inducements to eat (e.g., shared meals) or on motivation for weight control.     

Marriage,gender and obesity in later life

A large body of literature argues that marriage promotes health and increases longevity. But do these benefits extend to maintaining a healthy body weight, as the economic theory of health investment suggests they should? They do not. Using the Health and Retirement Study (HRS), I find that entry into marriage among both men and women aged 51–70 is associated with weight gain and exit from marriage with weight loss. I evaluate three additional theories with respect to the cross-sectional and longitudinal variation in the data. First, it may be that a broader set of shared risk factors (such as social obligations regarding meals) raises body mass for married couples. However, the shared risk factor model predicts that the intra-couple correlation should increase with respect to marital duration. Instead, it declines. Second, scholars have recently promoted a “crisis” model of marriage in which marital transitions, not marital status, determine differences in body mass. The crisis model is consistent with short-term effects seen for divorce, but not for the persistent weight gains associated with marriage or the persistent weight loss following widowhood. And transition models, in general, cannot explain significant cross-sectional differences across marital states in a population that is no longer experiencing many transitions, nor can it account for the prominent gender differences (in late middle-age, the heaviest group is unmarried women and the lightest are unmarried men). Third, I argue that pressures of the marriage market, in combination with gendered preferences regarding partner BMI, can account for all the longitudinal and cross-sectional patterns found in the data.     

Marriage: an evolutionary perspective

Marriage is universal, and pair bonding is found in other species too with highly dependent young. So marriage functions as a reproductive social arrangement that traditionally involved the extended family. The sexes are not identical in their biological contributions to children's survival, so they seek somewhat different attributes in a mate. Men seek a young, attractive, sexually faithful bride. Women seek a man who is older, taller, and (as in many other species) socially dominant. Both sexes prefer a kind, healthy, attractive, similar mate who is emotionally attached to them. A spouse who fails to maintain sufficiently high mate value is vulnerable to divorce. Infertility and sexual dissatisfaction predict divorce, as does death of a child, but the more children, the stabler the marriage. Cross-cultural data suggest that cruel or subdominant men (e.g., poor providers) and unfaithful women are prone to divorce. Marriages in which the wife dominates the husband in economic contributions, nonverbal behavior, and decision making tend to be less satisfying. In societies in which wives are economically independent of husbands, divorce rates are high. As women's economic power has risen with industrialization, divorce rates have climbed. Economic and fitness considerations also help explain cultural differences in polygyny, age at marriage, arranged marriage, concern with the bride's sexual chastity, and marriage ceremonies. Other factors also affect marital dynamics, such as state subsidies to families, the sex ratio, and influence of the couple's parents.     

Social stimuli cause changes of plasma oxytocin and behavior in guinea pigs

The neuropeptide oxytocin (OXT) is a key factor in the initiation and regulation of sociosexual behavior. The present study analyzes the effects of cohabitation and social challenge on plasma OXT concentration rates in guinea pig pairs in relation to male sociosexual behavior. The cohabitation phase lasted 3 days. On day 4, the pair was socially challenged by introducing an unfamiliar male. Displayed male sexual behavior varied significantly during cohabitation, with peaks on day 1. Sociopositive behavior, i.e., side-by-side contact, was increased on days 3 and 4. Cohabitation per se led to elevated plasma OXT concentrations only in males. In contrast, both sexes reacted with increased plasma OXT concentrations to the social challenge (day 4). At that time, male OXT was significantly correlated with sexual behavior and female OXT with sociosexual behavior received from the partner. Additionally, pairs were synchronized in their OXT release during days 3 and 4. We conclude that cohabitation causes sexually dimorphic plasma OXT concentration patterns in guinea pigs. Secondly, the conformity of OXT release in both sexes may represent an endocrine marker for long-term cohabitation, which is reflected behaviorally by increased spatial proximity.     

Divorce in the early years of marriage in England and Wales: results from a prospective study using linked records

A representative sample of over 1000 couples who married during 1979 in England and Wales was followed from the date of marriage until mid-1984 to investigate the characteristics of couples who divorce soon after marriage. Results of this 5 year study show that couples who apparently lived together before marriage had a below average chance of early divorce, whereas couples where the addresses of the partners before marriage were very close had a significantly high rate of early breakdown. The chance of early divorce was significantly above average for spouses marrying in their teens and for both husbands and wives who, at their marriage, belonged to social class 5 (work in unskilled manual occupations). Couples who married with a civil ceremony had an above average (and those marrying with a religious ceremony a below average) risk of early divorce, but such differences were found to be negligible on analyzing the results from a matched case-control study in which each "case" marriage (one which did end in early divorce) was matched with a "control" marriage (one which did not end in early divorce). There is substantial evidence that age at marriage and previous marital status of the marriage partners have a decided influence upon the propensity to divorce. 2 conclusions concerning fertility are more likely than the average married couple to have had a pre-maritally conceived child, and 2) that couples who divorce relatively quickly tend on average to have larger family sizes, even if children who were pre-martitally conceived are exluded.     

A two-sex demographic model with single-dependent divorce rate

Divorce appears to be one of the least studied demographic processes, both empirically and in two-sex demographic models. In this paper, we study mathematical as well as biological implications of the assumption that the divorce rate is positively affected by the amount of single (i.e., unmarried/unpaired) individuals in the population. We do that by modifying the classical exponential two-sex model accounting for pair formation and separation. We model the divorce rate as an increasing function of the single population size and show that the single population pressure on the established couples alters the exponential behavior of the classical model in which the divorce rate is assumed constant. In particular, the total population size becomes bounded and a unique positive equilibrium exists. In addition, a Hopf bifurcation analysis around the positive equilibrium shows that the modified model may exhibit sustained oscillations.     

Children's health and their mothers’ risk of divorce or separation

Abstract

The purpose of this study is to determine how children's health conditions are related to their mothers’ risk of divorce or separation. The study is based on data from over 7,000 children born to once‐married mothers identified in the 1988 Child Health Supplement to the National Health Interview Survey. The effects of 15 childhood health conditions on the mothers’ risk of divorce are estimated with Cox's proportional hazard models. Controlling for demographic, marital, and reproductive measures, we find that mothers’ prospects for divorce are affected both positively or negatively by their children's health status, depending on the type of childhood condition and, in the case of low birth weight children, timing within the marriage. Women whose children have congenital heart disease, cerebral palsy, are blind, or had low birth weight appear to have higher risks of marital disruption than mothers of healthy children. In contrast, mothers whose children have migraines, learning disabilities, respiratory allergies, missing/deformed digits or limbs, or asthma have somewhat lower rates of divorce.     

Explaining Marital Patterns and Trends in Namibia: A Regression Analysis of 1992, 2000 and 2006 Demographic and Survey Data

Background

Marriage is a significant event in life-course of individuals, and creates a system that characterizes societal and economic structures. Marital patterns and dynamics over the years have changed a lot, with decreasing proportions of marriage, increased levels of divorce and co-habitation in developing countries. Although, such changes have been reported in African societies including Namibia, they have largely remained unexplained.

Objectives and Methods

In this paper, we examined trends and patterns of marital status of women of marriageable age: 15 to 49 years, in Namibia using the 1992, 2000 and 2006 Demographic and Health Survey (DHS) data. Trends were established for selected demographic variables. Two binary logistic regression models for ever-married versus never married, and cohabitation versus married were fitted to establish factors associated with such nuptial systems. Further a multinomial logistic regression models, adjusted for bio-demographic and socio-economic variables, were fitted separately for each year, to establish determinants of type of union (never married, married and cohabitation).

Results and Conclusions

Findings indicate a general change away from marriage, with a shift in singulate mean age at marriage. Cohabitation was prevalent among those less than 30 years of age, the odds were higher in urban areas and increased since 1992. Be as it may marriage remained a persistent nuptiality pattern, and common among the less educated and employed, but lower odds in urban areas. Results from multinomial model suggest that marital status was associated with age at marriage, total children born, region, place of residence, education level and religion. We conclude that marital patterns have undergone significant transformation over the past two decades in Namibia, with a coexistence of traditional marriage framework with co-habitation, and sizeable proportion remaining unmarried to the late 30s. A shift in the singulate mean age is becoming distinctive in the Namibian society.     

Within-season divorce in Blue Tits (Cyanistes caeruleus)

Divorce between breeding seasons, i.e. mate change while the old breeding partner is still alive, has been well-studied in several bird species. It can be viewed either as the result of reproductive decisions of individuals to maximize their own fitness or as the outcome of intra-sexual competition for mating opportunities. In contrast, divorce within a breeding season—also referred to as rapid mate switching—has received much less attention. Within-season divorce may occur after sudden changes in environmental conditions, such as those causing the disappearance or devaluation of nesting sites or territories, or when better breeding partners become available. Within-season divorce can be initiated by a member of the pair, or it can be the result of a take-over by an unpaired individual that competes for access to the resource. During a field experiment investigating the effects of limiting nesting sites on reproductive behaviour in Blue Tits, we recorded several cases of within-season divorce. The rate of divorce was not related to the experimental nest-site limitation, and pairs that changed their partner suffered reduced reproductive success compared to faithful pairs. Although there were no differences in the timing of breeding, clutch size or hatching success, pairs with a new partner also suffered a reduced fledging success, which was partly explained by complete brood failures. This study highlights that the pair bond prior to egg laying can be unstable when conditions force individuals to compete for a new partner or nest site and indicates the importance of the correct timing of divorce within the breeding cycle.     

Unemployment and marital status in Great Britain.

During the past decade, the marriage rate has declined and the divorce rate has increased in Great Britain. Becker (1981) attributes such changes to improvements in the economic status of women, in that high-wage women gain less from marriage relative to other women. However, an empirical analysis of data from the General Household Survey 1985 in Great Britain shows that male unemployment is another important determinant of changes in marital status. High rates of male unemployment reduce the incidence of marriage and increase the likelihood of divorce.     

Postweaning environmental and social factors influencing the onset and expression of agonistic behavior in Norway rats

Two studies were conducted to determine the importance of the postweaning environment and social milieu in regulating the expression of intraspecific aggression in Norway rats. In Experiment 1, male rats were housed either individually or in pairs at 21 days of age. In addition, one-half of the singly housed and paired animals were given experiences with intruders during maturation. At 85 days of age, all animals were given a brief intruder test and then removed from their postweaning environment and provided individually with homecages for a two week period until tested for aggression toward intruders. Results of intruder tests given during maturation indicated agonistic exchanges appeared earlier and more frequently in cages housing a single resident than cages with cohabiting males. However, agonistic exchanges between singly reared residents and intruders had detrimental consequences in adulthood especially under long-term combat situations. That is, although individually reared animals, with early fighting experiences, were capable of initiating intraspecific aggression, such individuals were unable to defend their homecage over a long period of time as evidenced by the high number of wounds and tendency to lose body weight during adult fighting.In Experiment 2, male Norway rats were reared in pairs from 21 days of age and identified as dominant or subordinate on the basis of intracolony social interactions shown during maturation. At 80 days of age, animals were paired with individually reared males in an unfamiliar cage for a 20 day period and examined for agonistic behavior toward intruders at 100 days of age. Group-reared subordinate males exhibited defensive behavior during confrontations with individually reared animals and incurred more wounds and lost more body weight than their cohabiting partner. In addition, subordinate males showed significantly fewer offensive postures toward intruders than individually reared cohabitants. In contrast, group-reared dominant animals did not differ from individually reared males in display of agonistic patterns, in number of wounds, and body weight changes during the period of cohabitation. These findings demonstrate that early rearing factors have pronounced effects on agonistic behavior. Animals experiencing defeat during development are more likely to lose agonistic confrontations in unfamiliar territory than either animals dominant in their early social interactions or animals without the experience of winning or losing agonistic encounters. These results have implications for the understanding of agonistic behavior and predicting outcomes of animal contests, and reveal important differences in agonistic experiences among animals reared in groups.     

Delay and Probability Discounting of Sexual and Monetary Outcomes in Individuals with Cocaine Use Disorders and Matched Controls

Individuals with cocaine use disorders are disproportionately affected by HIV/AIDS, partly due to higher rates of unprotected sex. Recent research suggests delay discounting of condom use is a factor in sexual HIV risk. Delay discounting is a behavioral economic concept describing how delaying an event reduces that event’s value or impact on behavior. Probability discounting is a related concept describing how the uncertainty of an event decreases its impact on behavior. Individuals with cocaine use disorders (n = 23) and matched non-cocaine-using controls (n = 24) were compared in decision-making tasks involving hypothetical outcomes: delay discounting of condom-protected sex (Sexual Delay Discounting Task), delay discounting of money, the effect of sexually transmitted infection (STI) risk on likelihood of condom use (Sexual Probability Discounting Task), and probability discounting of money. The Cocaine group discounted delayed condom-protected sex (i.e., were more likely to have unprotected sex vs. wait for a condom) significantly more than controls in two of four Sexual Delay Discounting Task partner conditions. The Cocaine group also discounted delayed money (i.e., preferred smaller immediate amounts over larger delayed amounts) significantly more than controls. In the Sexual Probability Discounting Task, both groups showed sensitivity to STI risk, however the groups did not differ. The Cocaine group did not consistently discount probabilistic money more or less than controls. Steeper discounting of delayed, but not probabilistic, sexual outcomes may contribute to greater rates of sexual HIV risk among individuals with cocaine use disorders. Probability discounting of sexual outcomes may contribute to risk of unprotected sex in both groups. Correlations showed sexual and monetary results were unrelated, for both delay and probability discounting. The results highlight the importance of studying specific behavioral processes (e.g., delay and probability discounting) with respect to specific outcomes (e.g., monetary and sexual) to understand decision making in problematic behavior.     

Gender differences in predictors of body weight and body weight change in healthy adults

Background: Overweight and obesity are important predictors of a wide variety of health problems. Analysis of naturally occurring changes in body weight can provide valuable insights in improving our understanding of the influence of demographic, lifestyle, and psychosocial factors on weight gain in middle‐age adults. Objective: To identify gender‐specific predictors of body weight using cross‐sectional and longitudinal analyses. Methods and Procedures: Anthropometric, lifestyle and psychosocial factors were measured at baseline and then quarterly for 1 year in 572 healthy adult volunteers from Central Massachusetts who were recruited between 1994 and 1998. Linear mixed models were used to analyze the relationship between body weight and potential predictors, including demographic (e.g., age, educational level), lifestyle (e.g., diet, physical activity, smoking), and psychosocial (e.g., anxiety, depression) factors. Results: Over the 1‐year study period, on average, men gained 0.3 kg and women lost 0.2 kg. Predictors of lower body weight at baseline in both men and women included current cigarette smoking, greater leisure‐time physical activity, and lower depression and anxiety scores. Lower body weights were associated with a lower percentage of caloric intake from protein and greater occupational physical activity levels only among men; and with higher education level only among women. Longitudinal predictors of 1‐year weight gain among women included increased total caloric intake and decreased leisure‐time physical activity, and among men, greater anxiety scores. Discussion: Demographic, lifestyle and psychosocial factors are independently related to naturally occurring changes in body weight and have marked differential gender effects. These effects should be taken into consideration when designing interventions for weight‐loss and maintenance at the individual and population levels.     

The effects of prospective mate quality on investments in healthy body weight among single women

This paper examines how a single female's investment in healthy body weight is affected by the quality of single males in her marriage market. A principle concern in estimation is the presence of market-level unobserved heterogeneity that may be correlated with changes in single male quality, measured as earning potential. To address this concern, we employ a differencing strategy that normalizes the exercise behaviors of single women to those of their married counterparts. Our main results suggest that when potential mate quality in a marriage market decreases, single black women invest less in healthy body weight. For example, we find that a 10 percentage point increase in the proportion of low quality single black males leads to a 5–10% decrease in vigorous exercise taken by single black females. Results for single white women are qualitatively similar, but not consistent across specifications. These results highlight the relationship between male and female human capital acquisition that is driven by participation in the marriage market. Our results suggest that programs designed to improve the economic prospects of single males may yield positive externalities in the form of improved health behaviors, such as more exercise, particularly for single black females.     

Estimation of Duration of Separation, Widowhood, and Family Life Cycle

This is the second of two reports on a study of the durations related to marriage. Divorce and death of one's spouse, the main causes of dissolution of marriage, are two of the most important events in a person's life. In the United States in 1994, 30.7 million, or 16.2%, of the adult population were either divorced or widowed. Among the widowed, the female to male ratio was 5 to 1! In this paper duration of separation due to divorce and duration of widowhood are the main variables under study. Algebraic formulas are derived and computer programs are written for estimating these durations for husbands and wives, and for living couples of any age. Relations with the duration of marriage, the expectation of life, and the family life cycle are also presented.     

Assortative marriage for physical characteristics in newlyweds

The objective of this study was to estimate the degree of spouse resemblance in the first 6 months of marriage and to compare these estimates with those of previous studies on long-standing marriages. The participants, 215 couples, were selected from the marriage licenses issued in two counties within the San Francisco Bay Area. They attended one of several group sessions in which questionnaires were filled out and forearm length measurements were taken. Only the results for the couples of European ancestry (N = 164) are presented here since the other subsamples were too small to analyze separately. The husband-wife correlations for body size were found to be essentially equal to those in long-standing marriages. Thus, it appears that physical resemblance in couples is the result of initial assortment rather than convergence arising from long cohabitation. A significant residual husband-wife correlation for weight was found after statistically partialing out height. It may be that assortative marriage for food habits and attractiveness produces spouse resemblance in weight, independently of height. Alternatively, convergence in eating habits may occur during courtship and the early months of marriage which may increase the resemblance in weight. There was very little homogamy for eye color independently of race, and no evidence of assortative marriage for handedness.     

Multiple Phenotypic Changes Associated with Large-Scale Horizontal Gene Transfer

Horizontal gene transfer often leads to phenotypic changes within recipient organisms independent of any immediate evolutionary benefits. While secondary phenotypic effects of horizontal transfer (i.e., changes in growth rates) have been demonstrated and studied across a variety of systems using relatively small plasmids and phage, little is known about the magnitude or number of such costs after the transfer of larger regions. Here we describe numerous phenotypic changes that occur after a large-scale horizontal transfer event (∼1 Mb megaplasmid) within Pseudomonas stutzeri including sensitization to various stresses as well as changes in bacterial behavior. These results highlight the power of horizontal transfer to shift pleiotropic relationships and cellular networks within bacterial genomes. They also provide an important context for how secondary effects of transfer can bias evolutionary trajectories and interactions between species. Lastly, these results and system provide a foundation to investigate evolutionary consequences in real time as newly acquired regions are ameliorated and integrated into new genomic contexts.     

Effect of rabbit doe-litter separation on 24-hour changes of luteinizing hormone,follicle stimulating hormone and prolactin release in female and male suckling pups

Background  

The daily pattern of nursing of the rabbit pup by the doe is the most important event in the day for the newborn and is neatly anticipated by them. Such anticipation presumably needs a close correlation with changes in hormones that will allow the pups to develop an appropriate behavior. Although a number of circadian functions have been examined in newborn rabbits, there is no information on 24-h pattern of gonadotropin release or on possible sex-related differences in gonadotropin or prolactin (PRL) release of pups. This study examined the 24-h changes of plasma luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) in 11 days old suckling female and male rabbits left with the mother or after short-term (i.e., 48 h) doe-litter separation.     

Childhood adversity,attachment security,and adult relationships: A preliminary study

Several evolutionary theorists have linked early rearing context to later reproductive strategy, hypothesizing that strategies differentiate during development as functional responses to ecological characteristics, by individuals or through parental manipulation. Attachment security has been proposed as a mediator. In this study, 40 young adults were given a multidimensional assessment, including the Hazen and Shaver Adult Attachment Questionnaire. Twenty-four subjects were classified as having secure attachment styles, 16 as nonsecure. The magnitude and predictability of parental investment during childhood was classified as lower if there was a brief intersibling interval, parental divorce, fewer economic resources, or less nurturing parents (i.e., more childhood adversity). Several such indicators were present for 17 people, 12 of whom were nonsecure, compared to only 4 of the 23 others. The nonsecurely attached subjects were less likely to have attained enduring marriages. The 6/16 nonsecure who had a marriage or cohabitation began them at a younger age and after a shorter courtship period than did the 15/24 secure with such relationships. Separations or divorces had already occurred in the relationships of 4/6 nonsecure versus 5/15 secure. Attachment security was associated with childhood adversity and adult relationships for both men and women, when analyzed separately. A retrospective study cannot address cause and effect, because poor adult relationship outcomes might bias recall of parental behavior. However, results are consistent with theories that unpredictable early environments foster short-term rather than long-term mating strategies, possibly through affecting attachment styles.     

Simultaneous observation of ingestive and copulatory behavior of the male rat.

In a preliminary test male rats were allowed to ingest a 1 M solution of sucrose from a drinking spout. After daily intake of sucrose became stabilized, the males were given a sexually receptive or non-receptive female and the bottle filled with sucrose solution simultaneously. The ingestive and copulatory behavior was observed for 60 min under illumination by a red lamp. The data obtained from this study showed that the ingestive behavior of males was suppressed by the presence of sexually receptive females and, conversely, the sexual behavior of males was not affected by the presence of a bottle of sucrose. These results suggest that the presence of a sexual partner inhibits appetitive ingestive behavior, i.e., the responses used by male rats to obtain food.