Correlates of testosterone change as men age.

Objective: The literature on testosterone (T) in men reports diverse correlates of T, some with minimal empirical support and most with little indication of how they change with advancing age. We test eight putative correlations across age.Method: Correlations were tested on a large sample of British men.Results: Seven of eight correlations replicated. Most change across men's life courses. The diurnal cycle of T is considerably weaker among older than younger men. Single men have higher T than married men of the same age; however, this difference lessens as men get older. Elevated T among smokers is less pronounced as men age. The inverse relationship between obesity and T is sustained across the adult age range. The lessening of T with age is well established, however there is disagreement about the course of decline. We find T having a steep decline around age 30, with possibly a rebound around age 50, after which levels remain roughly constant. Correlations involving health become stronger among older men. After age 30 or 40, the inverse relationships between T and HbA1c, diabetes, and metabolic syndrome all become increasingly significant, though not necessarily strong in magnitude.Conclusion: Most putative correlates of T are replicated. There is a basis here for the generalization that among older men, those healthy have higher T than those who are not, but not a lot higher.

Enzyme immunoassay may be inadequate for measuring salivary testosterone in older men.

Several correlations have been reported between men's testosterone (T) and other characteristics. Stalwart findings are a decline in T during the day, decline with obesity, and decline with advancing age. Here seven previously reported correlations are tested among older American men in the National Social Life, Health and Aging Project (NSHAP), their salivary T measured by enzyme immunoassays (EIA). Few significant correlations are found, with most tests producing weak or null results. These findings, overall, suggest that T does not "work" much among older men. However, a threat to this conclusion is raised by Welker et al. namely that EIA of salivary T may contain large errors, invalidating the tests. To check this possibility, these correlations from the literature were tested among older British men whose salivary T was measured by liquid chromatography-tandem mass spectroscopy (LC-MS/MS), a technique noted for its specificity. Not all could be tested, but the relationships of T with age, obesity, and health are significant among British men, indicating that T remains active in older men, and throwing doubt on the adequacy of EIA for measuring salivary T.

Testosterone in biosociology: A memoir.

A contribution to a special issue on Hormones and Human Competition. The author looks back at his four decades of research on testosterone in the context of biosociology - its accomplishments, pitfalls, outstanding questions, and future directions.

Identification of visual paternity cues in humans.

Understanding how individuals identify their relatives has implications for the evolution of social behaviour. Kinship cues might be based on familiarity, but in the face of paternity uncertainty and costly paternal investment, other mechanisms such as phenotypic matching may have evolved. In humans, paternal recognition of offspring and subsequent discriminative paternal investment have been linked to father-offspring facial phenotypic similarities. However, the extent to which paternity detection is impaired by environmentally induced facial information is unclear. We used 27 portraits of fathers and their adult sons to quantify the level of paternity detection according to experimental treatments that manipulate the location, type and quantity of visible facial information. We found that (i) the lower part of the face, that changes most with development, does not contain paternity cues, (ii) paternity can be detected even if relational information within the face is disrupted and (iii) the signal depends on the presence of specific information rather than their number. Taken together, the results support the view that environmental effects have little influence on the detection of paternity using facial similarities. This suggests that the cognitive dispositions enabling the facial detection of kinship relationships ignore genetic irrelevant facial information.

Testosterone and type 2 diabetes in men.

OBJECTIVE: To assess from observational data if low testosterone in men is an independent risk factor for high fasting glucose (FG) and for a diagnosis of type 2 diabetes (T2D). METHODS: Multivariate analysis of data from 991 male US Air Force veterans who completed six medical examinations over 20 years. RESULTS: Low testosterone was moderately related to high FG, independent of age and obesity. Low testosterone is a very weak predictor of a diagnosis of T2D. CONCLUSIONS: In men, low testosterone is an independent risk factor for high FG, comparable to aging and obesity. Low testosterone is a weak predictor of a diagnosis of T2D.

Why were "starvation diets" promoted for diabetes in the pre-insulin period?

In the decade before the discovery of insulin, the prominent American physicians Frederick Allen and Elliott Joslin advocated severe fasting and undernutrition to prolong the lives of diabetic patients. Detractors called this "starvation dieting," and some patients did indeed starve to death. Allen and Joslin promoted the therapy as a desperate application of animal experimentation to clinical treatment, and texts still describe it that way. This justification was exaggerated. The public record contains only the briefest account of relevant animal experiments, and clinical experience at the time provided little indication that severe undernutrition had better outcomes than low carbohydrate diets then in use.

The age-testosterone relationship in black, white, and Mexican-American men, and reasons for ethnic differences.

Recent studies give contradictory findings regarding testosterone levels in white, black, and Hispanic men. Here, I present a cross-sectional reanalysis of serum testosterone and sex hormone-binding globulin (SHBG) in 1637 males, aged 12-90, who participated in the morning examination of the Third National Health and Nutrition Examination Survey (NHANES III) during the year 1988-1991. Testosterone and SHBG in males are described precisely over the age range 12 to 90 years. Testosterone and SHBG are not notably different in white and Mexican-American (MA) males. In the age range 20-69 years, black men average 0.39 ng/ml higher testosterone than white and MA men (p < 0.001). The higher testosterone in black men is partly explained by low marriage rate and low adiposity.

How bad can a crisis be if it does not top the news?

Sudden onset of front-page news about the U.S. financial crisis, beginning September 6, 2008, may have exacerbated underlying financial problems and facilitated the spread of risk panic to other nations.

How did the fracking controversy emerge in the period 2010-2012?

In 2010-2012, the controversy over fracking grew rapidly, first in the United States, and then internationally. An important step was the anti-fracking documentary film Gasland. With help from celebrity sources, the film was produced and won a prize at the Sundance Film Festival by early 2010 and had an Oscar nomination by early 2011, in the meantime popularizing potent images of hazard including tainted aquifers and ignitable water running from kitchen faucets. During this period, major US news organizations paid little attention to the issue. The offshore Deepwater Horizon disaster of April 2010 spurred The New York Times to prolific reporting on potential risks of the new onshore technique for extracting shale gas. With flagship news coverage, the controversy had by 2012 gained wide media attention that evoked public concern and opposition, spreading from the United States to other nations.

Does the Biosocial Model Explain the Emergence of Status Differences in Conversations among Unacquainted Men?

Fifteen triads of unacquainted men conversed for ten minutes while stress was measured in real time by pulse rate and thumb blood volume (TBV). Salivary measures of testosterone (T), cortisol (C), and the stress-related enzyme alpha-amylase (AA) were measured at the beginning and end of the session. Fully or partially transitive status hierarchies formed in 14 triads. (Highest ranked man was scored 1, lowest 3, with ties allowed.) Ten of the triads participated in Study 1, where nothing was at stake in the casual conversation. Five additional triads were run in Study 2, intended to introduce competition by offering a $20 reward to the man afterward chosen as having led the conversation. Most results from the two studies are similar, suggesting that the $20 reward had little effect. Combining studies, pulse and TBV show that conversation is more stressful than watching a video beforehand. Within the conversation, speaking turns are more stressful than listening turns, especially among the lowest ranked men, less so among those higher in rank. This supports a stress-based mechanism for status allocation among humans. Apparently, human speech is a form of status signaling, homologous with nonlinguistic status signals used by other primates, as posited by the "biosocial model." The biosocial model also posits that a physiological substrate (T, C, and AA) is related to dominance or status. Predicted effects are not replicated here, except for an inverse relationship between the stress enzyme AA and status. The mostly null results, obtained from conversations where there was little or nothing at stake, suggest that T and C (and their interaction) are not relevant to emergent status in the absence of serious competition.

Beyond linguistic alignment.

Dialogue requires ability beyond the production and comprehension of word strings. The interactive alignment account is good as far as it goes, but it must be embedded in a broader model encompassing alignment of paralinguistic representations.

Testosterone is related to deviance in male army veterans, but relationships are not moderated by cortisol.

The Vietnam Experience Study (VES) of 4462 male U.S. Army veterans is the first large dataset used to demonstrate that testosterone (but not cortisol) is correlated with diverse measures of antisocial, aggressive or dominant behavior. Many subsequent studies have sustained these relationships while also pointing to important caveats. Some researchers suggest that testosterone is correlated to dominance and aggression only (or mostly) in people with low cortisol, not in those with high cortisol. Here we look back to the VES to test this "dual hormone" hypothesis. We find no testosterone-cortisol interaction for seven measures of antisocial deviance. We consider scope conditions under which the dual hormone hypothesis may be valid.

Is rising obesity causing a secular (age-independent) decline in testosterone among American men?

The testosterone of men in industrial societies peaks in their twenties and tends to decline with increasing age. Apart from this individual-level decline, there have been reports of a secular (age-independent population-level) decline in testosterone among American and Scandinavian men during the past few decades, possibly an indication of declining male reproductive health. It has been suggested that both declines in testosterone (individual-level and population-level) are due to increasing male obesity because men in industrial society tend to add body fat as they age, and overall rates of obesity are increasing. Using an unusually large and lengthy longitudinal dataset (991 US Air Force veterans examined in six cycles over 20 years), we investigate the relationship of obesity to individual and population-level declines in testosterone. Over twenty years of study, longitudinal decline in mean testosterone was at least twice what would be expected from cross-sectional estimates of the aging decline. Men who put on weight intensified their testosterone decline, some greatly so, but even among those who held their weight constant or lost weight during the study, mean testosterone declined 117 ng/dl (19%) over 20 years. We have not identified the reason for secular decline in testosterone, but we exclude increasing obesity as a sufficient or primary explanation, and we deny the supposition that men who avoid excessive weight will maintain their youthful levels of testosterone.

The role of testosterone in male dominance contests that turn violent.

Usually face-to-face dominance contests between humans are nonviolent, even amiable. Most violence between young men occurs when dominance contests infrequently escalate beyond their usually bounds. Heightened testosterone is not a direct cause of male violence. Occasional outbreaks of violence occur for other reasons, and are often random outcomes. However testosterone does encourage (nonviolent) dominant behavior among young men, increasing the frequency of dominance contests, hence increasing the likelihood of violent outcomes. "Honor subcultures" such as are found in our inner cities place inordinate importance on the enhancement of personal reputations and the humiliation of losing face. This atmosphere of persistent challenge produces heightened testosterone in young black men of the inner city, raising the likelihood that they will engage in dominance competition, which in turn raises the likelihood of a violent, even fatal, outcome.

Testosterone supplementation in the aging male: which questions have been answered?

PURPOSE: There is no consensus on possible benefits and risks of testosterone supplementation. Here we review various controlled studies of testosterone supplementation in aging males. METHODS: We performed a PubMed search using the terms "testosterone/therapeutic use" with the limits " > 65 years of age", "randomized controlled clinical trials", and "male gender", starting in 1999. RESULTS: Forty-three articles have been published since 1999. Some of these studies also included patients in middle-age or younger. Findings reported in these articles were not entirely consistent. After weighting studies by the number of patients, hints are found that testosterone supplementation increases bone mass, lean body mass, muscle mass and hematopoiesis, and improves sexual functioning and perhaps mood, but does not affect serum lipids, cardiovascular parameters, prostate-specific antigen level, or cognition. Considering studies including only men older than 65 years, and in which testosterone supplements were compared with placebo treatment, slightly different results are obtained. In these patient groups, testosterone does not improve sexual function or mood. CONCLUSION: The overall benefit of testosterone supplementation for the aging male remains unclear. Any supplementation in men with age-normal testosterone levels only on grounds of subjective symptoms is not advisable.

Believers and disbelievers in evolution.

BACKGROUND: Citizens of the United States are less likely than are citizens of Europe and several non-European nations to believe that humans evolved from an earlier species. Several theories have been proposed to explain Americans' disbelief in human evolution, but empirical investigation has been sparse. METHODS: Data on belief in evolution, on scientific knowledge unrelated to evolution, on socioeconomic status, on Christian religiosity, and on political polarity were identified in the General Social Surveys (GSSs) for 1993, 1994, and 2000. These data were then analyzed in bivariate and multivariate tests of theories about evolutionary and anti-evolutionary views. FINDINGS: Christian religiosity was the strongest correlate of disbelief in evolution. Low educational attainment was another positive, but weaker, correlate, though disbelief in evolution was not related to general measures of scientific knowledge. Political liberalism and political conservatism predicted evolutionary belief even after controlling for religiosity, education, and other potential confounders. Subcultural differences in belief -- those between blacks and whites, rural dwellers and urban dwellers, Southerners and non-Southerners, dogmatists and non-dogmatists -- became insignificant under appropriate controls. CONCLUSION: Christian religiosity, especially in a fundamentalist variety, was the primary correlate of disbelief in evolution. Lack of education was an important but lesser factor. Independent of religiosity and education, political conservatism predicted disbelief.