Social biology最新文献

While the basics of testosterone production, effects and metabolism have been known for decades, there has been a flow of novel insights in the genomics of testosterone action on a molecular and cellular level, as well as in the clinical effects from modern clinical trials, improving the understanding of the role of testosterone in male life course. Androgens are produced under the control of an endocrine cascade from GnRH via gonadotropins to the testicular Leydig cells. In some organs, testosterone is reduced to 5alpha-dihydrotestosterone prior to the receptor binding by the 5alpha reductase. The androgen receptor gene is located on the X chromosome in the q11-12 region, each mutation in the gene will induce phenotypic manisfestations. In the first stage of the male life course, testosterone moderates the male embryonic development under the control of a complex molecular genetic network. The next important phase of male maturation is the puberty, in which testosterone levels increase and induce the development of somatic and psychological characteristics of male sexuality. In the adult male, testosterone maintains sexual functions and fertility. In aging men, testosterone levels decrease slowly. Testosterone supplementation in the aging male is able to restore the function of androgen target organs only in part.

To determine age-related patterns of gonadotropins and their relationship to energetic status in a subsistence population we analyzed urinary FSH, LH, and estrone-3-glucuronide (E-3-G) along with anthropometric measures among Turkana males of northern Kenya. Subjects were 134 nomadic and 109 settled males ages 20 to 80+. FSH, LH and E-3-G were significantly higher among the settled, compared to nomadic, males. LH, but not FSH, showed a significant increase across 10 year age groups among all the men. E-3-G increased across age groups only among the settled males. Controlled for age, FSH was inversely related to measures of fat free and body mass among the settled men. These findings suggest an unusual age profile of gonadotropins and estrogen metabolites that may reflect the impact of fluctuating food availability. More research is needed to address the impact of energetic and social factors on the male reproductive axis among energetically stressed populations.

A lost less is known about the morbidity and mortality consequences of male infertility. It was the aim of our study to analyse the association between sperm concentration and individual lifetime mortality in men. The data sources included medical records of 601 men who attended the andrological service at the Marburg University Hospital between 1949 and 1985, and vital data gathered from public registration offices and a statutory health insurance. A Cox regression model estimated a two-fold higher mortality risk for oligozoospermic men as compared to the normozoospermic group for cohorts born between 1892 and 1931. Since a selection bias could not be found, we assume there to be a connection between poor fertility status and a shorter lifespan in men. Possible explanations for the variation in mortality risk are: (i) Lifestyle and health behaviour in adulthood, (ii) conditions in utero, and (iii) genetic dispositions.

Hunting performance may be one of the most important routes to high prestige or social status among men in hunter-gatherer societies. Higher social status based on hunting performance has been linked to higher biological fitness outcomes almost everywhere this relationship has been investigated. This paper explores the proximate pathways underlying the positive correlation between hunting success and fitness, and discusses these in light of recent debates concerning the role of men in hunter-gatherer societies. Meat obtained from hunting directly provisions families and is also distributed to other group members, who may directly or indirectly pay back good hunters with meat, other food, services or favors. The display of hunting abilities may also increase men's fitness through extra-marital reproductive gains. We discuss prior results and provide a novel additional example using data collected among Tsimane horticultural-foragers of Bolivia. Despite the impression that most of the benefits that accrue to good hunters are in the form of extra-marital mating opportunities, we argue instead that most benefits may be gained within rather than outside marital unions.

Racial and sex disparities in chronic diseases and mortality are sources of health inequality and have been observed from infancy to adulthood. Disparities in health and mortality contribute to corresponding disparities in healthy life. I address two previously unanswered questions in the aging literature. First, does the racial and sex gap in healthy life narrow, persist, or expand over age and time, particularly considering severity of ill health, among the oldest old? Second, do some race-sex groups of birth cohorts live not just longer lives, but longer healthier lives, while others spend additional years in illness? To estimate the quantities, I employ a refined definition of physical disability and apply a new extension of Sullivan's method to true birth cohorts. The results suggest among the oldest old, few racial or sex disparities exist over age and time in mild disability. Yet, racial and sex disparities persist over age and time in severe disability.

Early life conditions, such as socioeconomic status (SES) and health, have the potential to set in motion multiple and reinforcing pathways that shape both the prevalence and onset of diabetes among older adults. Using data from the Health and Retirement Study (1998-2002) for persons age 51 years and older, we investigated the core mediating mechanisms linking early life conditions with diabetes prevalence in 1998 and onset over a 4-year follow-up period, focusing on adult achievement processes and obesity as key mechanisms. We found that father's education is negatively associated with diabetes prevalence for older men and women. However, no markers of early life SES are directly associated with older men's and women's onset of diabetes, and the negative effects of adult SES on diabetes onset pertain only to women. Early life health affects the onset of diabetes among women--but not the prevalence--and no evidence of this association was found for men. We found no evidence that obesity is an important mechanism connecting either early life or adult SES with diabetes development in men or women. We speculate that early life SES may accelerate the development of diabetes at younger ages, and that the pathways linking life course SES, early life health, and diabetes are partly gender-specific and biological in nature.

We investigated the interplay between characteristics of early childhood circumstances and current socioeconomic conditions and health, focusing specifically on diabetes in mid and late life in Mexico. The analysis used data from the 2001 Mexican Health and Aging Study (MHAS), a large nationally representative study of Mexicans born before 1950. We analyzed the extent to which childhood conditions, such as exposure to infectious diseases, a poor socioeconomic environment, and parental education, affect the risk of diabetes in later life. Our results indicate that individuals age 50 and older who experienced serious health problems before age 10 have a higher risk of having late-life diabetes. There is a significant inverse relationship between maternal education and diabetes in late life of adult offspring. Individuals with better educated mothers have a lower risk of being diabetic after age 50. This relationship remains after controlling for other childhood and adult risk factors.

Anthropometric measures including height provide an indication of childhood health that allows exploration of relationships between early life circumstances and adult health. Height can also be used to provide some indication of how early life health is related to selection of migrants and the Hispanic paradox in the United States. This article joins information on persons of Mexican nativity ages 50 and older in the United States collected in the National Health and Nutrition Examination Survey IV (NHANES IV 1999-2002) with a national sample of persons of the same age living in Mexico from the Mexican Health and Aging Survey (MHAS 2001) to examine relationships between height, education, migration, and late-life health. Mexican immigrants to the United States are selected for greater height and a high school, rather than higher or lower, education. Return migrants from the United States to Mexico are shorter than those who stay. Height is related to a number of indicators of adult health. Results support a role for selection in the Hispanic paradox and demonstrate the importance of education and childhood health as determinants of late-life health in both Mexico and the United States.