Higher Male Mortality Research Articles

Culturally transmitted paternity beliefs and the evolution of human mating behaviour.

Recent anthropological findings document how certain lowland South American societies hold beliefs in 'partible paternity', which allow children to have more than one 'biological' father. This contrasts with Western beliefs in 'singular paternity', and biological reality, where children have just one father. Here, mathematical models are used to explore the coevolution of paternity beliefs and the genetic variation underlying human mating behaviour. A gene-culture coevolutionary model found that populations exposed to a range of selection regimes typically converge on one of two simultaneously stable equilibria; one where the population is monogamous and believes in singular paternity, and the other where the population is polygamous and believes in partible paternity. A second agent-based model, with alternative assumptions regarding the formation of mating consortships, broadly replicated this finding in populations with a strongly female-biased sex ratio, consistent with evidence for high adult male mortality in the region. This supports an evolutionary scenario in which ancestral South American populations with differing paternity beliefs were subject to divergent selection on genetically influenced mating behaviour, facilitated by a female-biased sex ratio, leading to the present-day associations of female control, partible paternity and polygamy in some societies, and male control, singular paternity and monogamy in others.

Sex Differences and Size at Emergence Are Not Linked to Biased Sex Ratios in the Common Green Darner, Anax junius (Odonata: Aeshnidae)

ABSTRACT Many species of dragonflies exhibit sexual dimorphism and biased sex ratios in adult populations. It is predicted that, in species with territorial adults, males should be larger than females at emergence. Larger male size should elevate foraging rate and lead to increased predation risk and higher male mortality during the larval stage. We tested these predictions for a territorial dragonfly, Anax junius, using laboratory and field experiments. We measured differences in growth and foraging activity between the sexes, determined sex ratios at emergence, and measured size at emergence for female and male dragonflies. Males gained more mass than females and males spent more time in motion and moved longer distances than females in foraging trials. Males were larger than females at emergence in natural populations, but sex ratios at emergence were not significantly different from 1:1. Sex-specific growth strategies in the larval stage did not result in biased sex ratios at emergence but may be important to the reproductive success of this territorial dragonfly.

Fatal pulmonary embolism, death rates and standardised mortality ratios after primary total hip replacement in a joint replacement centre

We determined retrospectively the postoperative mortality and fatal pulmonary embolism (PE) rates in 1275 consecutive primary total hip replacements (THR) in the six-week period after surgery at an orthopaedic hospital. Patients were traced by questionnaires, outpatient appointments and by telephone. Post-mortem records were used to verify cause of death. Follow-up was 100%. The death rate from PE was 0.16% (CI 0.04%-0.57%) and the all-cause mortality rate was 0.47% (CI 0.22%-1.02%). All deaths were within the first 10 days during the initial hospitalisation. The patient mortality was compared with the population mortality for England and Wales, using standardised mortality ratios (SMRs). The SMR for both sexes combined was 1.08 (CI 0.4-2.36). We observed a lower mortality in females (SMR=0.58; CI 0.07-2.09) but a higher mortality in males (SMR=1.91; CI 0.52-4.9) during the first 42 postoperative days compared to the general population. Fatal PE after THR without routine chemical thromboprophylaxis is uncommon. The death rate in patients undergoing THR appears to be similar to that in the general population.

The impact of sport-hunting on the population dynamics of an African lion population in a protected area

Between 1999 and 2004 we undertook an ecological study of African lions ( Panthera leo) in Hwange National Park, western Zimbabwe to measure the impact of sport-hunting beyond the park on the lion population within the park, using radio-telemetry and direct observation. 34 of 62 tagged lions died during the study (of which 24 were shot by sport hunters: 13 adult males, 5 adult females, 6 sub-adult males). Sport hunters in the safari areas surrounding the park killed 72% of tagged adult males from the study area. Over 30% of all males shot were sub-adult (<4 years). Hunting off-take of male lions doubled during 2001–2003 compared to levels in the three preceding years, which caused a decline in numbers of adult males in the population (from an adult sex ratio of 1:3 to 1:6 in favour of adult females). Home ranges made vacant by removal of adult males were filled by immigration of males from the park core. Infanticide was observed when new males entered prides. The proportion of male cubs increased between 1999 and 2004, which may have occurred to compensate for high adult male mortality.

Influence of Sex on Mortality in Hospitalized Patients With Congestive Heart Failure and Preserved or Depressed Systolic Function

There is some controversy about the impact of sex on mortality in patients with heart failure. Moreover, little is known about its influence on prognosis in patients with preserved systolic function. The objective of this study was to investigate the influence of sex on survival in patients with heart failure, including subgroups with preserved or depressed left ventricular ejection fraction (LVEF). The study included 1252 patients (767 male, 61.3%) who were admitted with heart failure to the cardiology department of a tertiary hospital. The median follow-up period was 2.3 years, with the mortality rate rising to 41% after 12 years of follow-up. A LVEF less than 50% was observed in 60.2% of patients. Female patients were older (73.4 +/- 10.0 years vs 66.8 +/- 11.9 years; P < .001), a higher proportion had preserved systolic function (52.2% vs 31.9%; P < .001), and fewer had ischemic cardiopathy (44.1% vs 53.2%; P < .001). In the group as a whole, the influence of sex on prognosis did not reach statistical significance: the hazard ratio in males compared with females was 1.253 (95%CI, 0.978-1.605; P = .074). In addition, no influence of sex on survival was observed in subgroups with preserved or depressed systolic function. In a large cohort, we did not observe any influence of sex on mortality in hospitalized patients with heart failure, either in the group as a whole or in subgroups with preserved or depressed left ventricular systolic function, despite a tendency towards higher mortality in males.

Population sex ratio variation in a monogamous long‐lived bird, the wandering albatross

Summary Factors affecting population birth sex ratio and variations of sex ratios within population in very long‐lived animals are poorly known, apart for humans that have attracted much attention. We measured the age and sex structure of a population of a monogamous long‐lived seabird, the wandering albatross Diomedea exulans, where reproductive performance of individuals is known, to examine factors affecting sex ratio variation and survival consequences of producing a particular sex. The overall sex ratio at hatching is significantly biased toward the production of males. Very young and old parents tend to produce an excess of female offsprings, whereas intermediate‐aged birds, which represent the bulk of the population, produce an excess of males. Low‐quality parents (quality is measured as average breeding success over the cumulated past breeding life, and is not related to condition or age) produce more female chicks compared with high‐quality parents that represent the bulk of the population. The combined effect of age and quality of parents produce an extensive sex ratio variation at the level of the population. The survival of male and female parents is influenced differently by their quality and by the sex of offspring. Male parents die in larger numbers when rearing a female chick, whereas low‐quality female parents have a lower survival, especially when they rear a male offspring, the sex needing higher parental investment. The differences between males and females parents’ survival are probably due their contrasted investment in parental care. After fledging, during the 5–8‐year period of immaturity, there is a much higher mortality of males that balances the surplus of males at hatching and fledging and results in a similar number of males and females at the time of recruitment. However, the overall operational sex ratio is male biased due to the slightly higher mortality of adult females that results in an excess of old widowed males: excluding these post‐reproductive males leads to an unbiased operational sex ratio. These results show that sex ratio at hatching varies extremely with the age and phenotypic quality of parents, and lead to a complex age and sex structure of the population in this strictly monogamous long‐lived species.

An Analysis on Factors of Russian Demographic Trends by Regions (1989-2002)

The Russian population decreased between the two censuses conducted in 1989 and 2002 as a result mainly of an increase in male mortality and a decline in birth rates. My previous research focused on premature death or the high mortality rate of the male working-age population. In this paper, multi-regression analyses are applied to regional data from Russia, in order to clarify the relationship between male mortality by age and socio-economic factors in each region. The use of regional mortality rate by age as an independent variable in this paper is a new approach in this field of studies.The result demonstrates that among socio-economic factors analyzed in this paper, a drink-related crime rate (the rate of crimes committed under the influence of alcohol per 10, 000 people) most significantly correlates to high male mortality, and especially to high mortality in the younger cohort of working-age males. As was shown by earlier research, the increase in male mortality in Russia was mainly brought about by such causes of death as trauma and poisoning, including suicide and homicide, and diseases of the circulatory system, all of which often originate in heavy consumption of alcohol. The conclusion of this paper also confirms this observation.By comparison with this factor, the economic factors analyzed in this paper, i.e. per capita money income and the unemployment rate, have weaker correlations to high male mortality. But both factors have statistical significance in regression equations concerning working-age males and the middle age cohort (35-44 years old) among them. While per capita income has a negative correlation with mortality, with respect to the unemployment rate a negative correlation (i.e., the lower the unemployment, the higher the mortality) is observed. This might be a result of heavy stress in industrially active regions, which could enhance mortality caused by trauma and poisoning. The fact that the effect of economic factors is not so significant compared with the drink-related crime rate might be explained by the use of 2002 data in this paper, rather than data from the early 1990s, i.e., the period of economic turmoil caused by system change. These problems and validity of other socio-economic factors remain to be answered.

HAPLODIPLOIDY AS AN OUTCOME OF COEVOLUTION BETWEEN MALE-KILLING CYTOPLASMIC ELEMENTS AND THEIR HOSTS

Haplodiploidy (encompassing both arrhenotoky and paternal genome elimination) could have originated from coevolution between male-killing endosymbiotic bacteria and their hosts. In insects, haplodiploidy tends to arise in lineages that rely on maternally transmitted bacteria for nutrition and that have gregarious broods in which competition between siblings may occur. When siblings compete, there is strong selection on maternally transmitted elements to kill males. I consider a hypothetical bacterial phenotype that renders male zygotes effectively haploid by preventing chromosome decondensation in male-determining sperm nuclei. By causing high male mortality, such a phenotype can be advantageous to the bacterial lineage. By eliminating paternal genes, it can also be advantageous to the host female. A simple model shows that the host female will benefit under a wide range of values for the efficiency of resource re-allocation, the efficiency of transmission, and the viability of haploid males. This hypothesis helps to explain the ecological correlates of the origins of haplodiploidy, as well as such otherwise puzzling phenomena as obligate cannibalism by male Micromalthus beetles, reversion to diploidy by aposymbiotic male stictococcid scale insects, and the bizarre genomic constitution of scale insect bacteriomes.

Differential seasonal mortality of the sexes in willow ptarmigan Lagopus lagopus in northern British Columbia, Canada

We assessed sex ratio, annual survival rates and patterns of seasonal mortality of female and male willow ptarmigan Lagopus lagopus in northwestern British Columbia. Annual sex ratio of birds on the breeding area did not statistically differ from a 1:1 ratio over eight years, although in six of the eight years males were more numerous. Over eight years, annual survival, based on return rates of banded birds, was 41–63% for males and 30–54% for females. We analysed seasonal patterns of mortality using radio‐tagged birds. During four springs and summers, female survival varied from 74 to 97%. They suffered the highest mortality during late prelaying, incubation and pre‐fledging brood rearing periods, and most were killed by raptors. Broodless females survived better (100%) than females accompanied by broods (77%). No radio‐tagged males died during two breeding seasons. Survival for both sexes was lower in autumn/winter (40–60%) than in spring/summer (75–100%). In autumn, the highest mortality for both sexes occurred during the late brood rearing and winter moult periods, coinciding with the autumn raptor migration. Both sexes had similar mortality rates over winter, despite separating by habitat. Another peak in male mortality occurred in late winter/early spring during the period of transient territoriality, whereas no females were killed during this time. From 1.4 to 3 times as many males as females were killed by hunters. Higher mortality of males during the hunting season and in late winter may balance the higher mortality of females during the breeding season, resulting in a breeding sex ratio that is close to unity.

Mortality patterns in the Russian Federation: indirect technique using widowhood data.

The Russian mortality crisis of the early 1990s attracted considerable attention, but information on possible covariates of mortality is lacking, and concerns have been raised about the validity of official mortality data. To help elucidate the determinants of mortality, we examined whether indirect demographic techniques could be used to study mortality in countries such as the Russian Federation, where mortality data are inadequate, using input data independent from official vital statistics. A national sample of the population was interviewed (n = 1600, response rate = 67%). Participants who had ever been married (82% of the sample) were asked about the date of birth and vital status of their first spouse. Spousal mortality was then estimated indirectly for the 531 men and 710 women for whom valid data were available. The estimated risk of death between the ages of 35-69 years was 57% for male spouses and 17% for female spouses. Corresponding figures derived from national data for 1990 were 52% and 25% for the Russian Federation, and 31% and 20% for the United Kingdom. According to spouses' reports, 38% of their husbands died from cardiovascular disease, 22% from cancer, and 14% from injuries and accidents. Mortality of male spouses was inversely related to the education level of their wives, and the age-adjusted hazard ratios for death from all causes, compared to primary education, were 0.77 for secondary education and 0.57 for university education (trend P = 0.03). Mortality was also inversely related to ownership of household items, but not to size of settlement, pride in Russia, membership in the Soviet Communist Party, nationality or self-assessed social status. Although the indirect estimates were imprecise (partly owing to the small population size of the study), and mortality in women was probably underestimated (owing to many factors, including poorer reporting by males and high male mortality), our results are nevertheless consistent with the mortality pattern observed in official mortality data. The indirect technique thus appears to be a useful tool to study the determinants of mortality in the Russian Federation and other populations, where reliable or sufficiently extensive data are not available.

Russia Faces Depopulation? Dynamics of Population Decline

Between 1992 and 1993 Russia's population declined, as it has in every succeeding year. This has been viewed as a population disaster, related to high adult male mortality and deterioration of the health care system. Some see a substantially depopulated Russia in the future. However, the prospect of long-term population decline is completely due to recent declines in fertility. High adult male mortality, although a cause of great concern, does not contribute to the chance of long-term population decline. Projections of the future population of Russia depend upon the exact fertility assumptions used. Based on the example of fertility in the United States in the Great Depression and the Baby Boom following World War II, the future depopulation of Russia is far from certain.

The Structural Determinants of Mortality in Japanese Prefectures

This cross‐sectional multivariate analysis of age‐ and sex‐standardized mortality for the 47 Japanese prefectures explores and tests the hypotheses that structural pluralism and differentiation, interpreted as dimensions of “social problem solving capacity”, determine lower mortality rates, controlling on the availability of medical facilities. The postulated explanatory principle is that participation in community problem‐solving optimizes the biological functioning of the residents, which fosters better health. A factor analysis generated two factors (plus a third index of medical facilities) that measure the structural dimensions. Regression analysis showed that pluralism predicted lower mortality for both males and females, but differentiation gave contradictory results. Surprisingly, medical facilities predicted higher male mortality. A control on the more recently industrialized and the hyper‐urbanized prefectures refined the analysis so that the differentiation factor predicted consistently and the spurious correlation between medical facilities and male mortality dissolved.

Female‐biased operational sex ratio of sexual host fish in a gynogenetic complex of Carassius auratus

To study the coexistence of sexual and gynogenetic forms, we examined the population structure of a gynogenetic complex of the Japanese crucian carp, Carassius auratus Temminck et Schlegel, during the April–June reproductive season by collecting 1225 mature fish that migrated from Lake Suwa to a tributary river for spawning. There were more sexual fish (about 80%) than gynogenetic fish in this complex, and the operational sex ratio in the sexual form was female biased (males were about 20%). Mean standard length and body weight of sexual females were larger than those of sexual males. Sex ratio was male biased in smaller fish (standard length, <8.5 cm) but female biased in larger fish (standard length, ≥8.5 cm). We determined age by scale ring marks; the average age of sexual females was higher than that of males, but there was no significant difference in the average age between sexual and gynogenetic females. Sex ratio in the sexual form was more female biased for old than for young fish, and the mean size of sexual females was larger than that of males of the same age. The clear female-biased sex ratio and age difference between sexual females and males can be explained either by (1) higher mortality of males or by (2) female-biased sex allocation. The latter process reduces the disadvantage of sex and contributes to the coexistence of sexual and gynogenetic forms.

Effect of spermine synthase deficiency on polyamine biosynthesis and content in mice and embryonic fibroblasts, and the sensitivity of fibroblasts to 1,3-bis-(2-chloroethyl)-N-nitrosourea

Mutant Gy male mice, which have previously been described as having disruption of the phosphate-regulating Phex gene and a spermine synthase gene [Meyer, Henley, Meyer, Morgan, McDonald, Mills and Price (1998) Genomics, 48, 289-295; Lorenz, Francis, Gempel, Böddrich, Josten, Schmahl and Schmidt (1998) Hum. Mol. Genet. 7, 541-547], as well as mutant Hyp male mice, which have disruption of the Phex gene only, were examined along with their respective normal male littermates. Biochemical analyses of extracts of brains, hearts and livers of 5-week-old mice showed that Gy males lacked any significant spermine synthase activity as well as spermine content. Organs of Gy males had a higher spermidine content. This was caused not only by the lack of conversion of spermidine into spermine, but also because of compensatory increases in the activities of other polyamine biosynthetic enzymes. Gy males were half the body weight of their normal male littermates at weaning age. Hyp males, however, were no different in size when compared with their controls. High mortality of Gy males occurs by weaning age and this mortality was shown to be largely post-natal. Embryonic fibroblasts were isolated from Gy males and their normal male littermates and were similarly shown to lack any significant spermine synthase activity as well as spermine content. The lack of spermine, however, had no significant effect on the growth of immortalized fibroblasts or of primary fibroblast cultures. Similarly, there was no difference in the time of senescence of primary fibroblast cultures from Gy males compared with cultures derived from normal male littermates. However, the lack of spermine did increase the sensitivity of immortalized fibroblasts to killing by the chloroethylating agent 1, 3-bis(2-chloroethyl)-N-nitrosourea. Therefore both the Gy male mice and derived embryonic fibroblasts provide valuable models to study the importance of spermine and spermine synthase, without the use of inhibitors which may have additional side effects.

The effect of drought stress on the sex ratio variation ofSilene otites

Under dry environmental conditions the sex ratio of many dioecious plants is male-biased, which is usually explained by the higher susceptibility of females to drought stress. We investigated if spatio-temporal variation in the sex ratio ofSilene otites could be explained by the higher sensitivity of female plants to drought stress as compared to males. Long-term field observations, however, did not support this hypothesis. The sex ratio in 34 patches at the study site in Central Germany changed from slightly female biased in 1994 to strongly male-biased in 1997 and 1998. The interannual change in the proportion of plants that were female was positively correlated with the number of days with soil-water deficit in the late summer, suggesting higher mortality in males than in females under drought stress. In two closely studied patches, mortality in males was also higher than in females, although this difference could not be related to drought stress. These field observations were supported by an experiment with potted plants in two climate chambers, in which male mortality was higher during a three-week period without water supply. We conclude that the often reported male bias in patches ofS. otites is not caused by sexual differences in the sensitivity to drought stress. Field data in this study, however, suggest that maleS. otites plants flower earlier than females, which causes a shift in sex ratio to more male bias among flowering plants.

New evidence for facultative male die-off in island populations of dibblers, Parantechinus apicalis

The post-mating mortality of males in dasyurid species is thought to be a specific life-history strategy, associated with a tightly synchronised breeding season, that may enhance survivorship of juveniles. Parantechinus apicalis has been reported to exhibit male die-off in island populations but not in mainland populations, and males originating from both island and mainland populations are known to survive post-mating in captivity. However, males in the island populations have been reported to sometimes survive to breed in a second year. This study monitored captive and island populations over a three-year period (April 1997 – May 2000) to examine the extent of male die-off. In captivity, males showed no evidence of post-mating mortality. Males on one island were also found to survive post-mating, while another island population appeared to have high mortality of males in three years, and a complete male die-off after the 1999 breeding season. We conclude that P. apicalis may warrant inclusion in a new category of life-history strategy for species exhibiting facultative male die-off.

Psychological Well-Being and Perceived Marital Opportunity Among Single African American, Latina and White Women

Research over the past decade has documented declining rates of marriage among African Americans and has identified constrained mate availability as a key determinant of this change. Many see Black marital decline as rooted in the deteriorating economic circumstances of significant segments of the African American population (especially males), as well as high male mortality and institutionalization. Discussions of the impact of diminished marital opportunity have focused on its societal consequences, with a particular emphasis on community-level outcomes. However, to date, there has been virtually no discussion of the mental health implications of limited marital opportunity. To the extent that marriage is still highly valued by most Americans, African Americans included. How does the recognition that one may not be able to assume a highly salient adult role affect subjective well-being? This article addresses the relationship between perceived marital opportunity and psychological well-being, as measured by depression, anxiety, loneliness, life satisfaction and relationship satisfaction, using data on single African American, Latina, and White women from the 1989 Southern California Social Survey. Our findings indicate that a perceived lack of availability is strongly associated with greater depression, anxiety, loneliness, and less satisfaction with life. The effect across all four dependents was strong and pervasive for Latinas and White women, but either weak or nonexistent for African American women. The correlation findings were supported by multiple regression analyses. Findings were interpreted as indicating that when the perception of mate availability is viewed as individually rooted and driven (an internal attribution), as was the case of both Latinas and White women, the consequences of psychological well-being are negative. When mate availability is viewed as a systemic feature of the environment over which one has little control (an external attribution), as was the case for Black women, mental health will not be affected. It is also suggested that single Black women have a greater range of positive role models, which are less available to other groups of women.

Sex ratio at birth deviations in modern Venezuela: The Trivers‐Willard effect

This study evaluates the impact of the Trivers-Willard (T-W) effect on human populations, using demographic data collected from vital registration data in Venezuela. The evaluation of the sex ratio at birth (SRB) and of fetal and infant deaths supports the existence of T-W effect in the Venezuelan population in extreme conditions. This T-W effect was observable in the SRB but not at later ages and is related to the marital status of the mother. The results indicate that the investment in females associated with environmental adversity is greater than the investment in males associated with good environmental conditions.

Influence of polycyclic aromatic hydrocarbons on the meiobenthic-copepod community of a Louisiana salt marsh

The influence of sediment contaminated with polycyclic aromatic hydrocarbons (PAHs) on the meiobenthic copepod community of a Louisiana salt marsh was examined with microcosms of sediment containing natural faunal assemblages. Microcosms were dosed with PAH-contaminated sediment that ranged in concentration from 0.3 (controls) to 27 mg PAH/kg dry sediment, and effects were followed for 28 days. Data suggest that highest doses (High-PAH) elicited avoidance behavior by Pseudostenhelia wellsi (Coull and Fleeger) copepods and nauplii, particularly 12 h after contaminants were added (Day 0). Weaker avoidance behavior was indicated in non- P. wellsi species that was manifested as increases in nauplius copepod ratios. Nematode copepod ratios were calculated for each of 4 species ( P. wellsi, Coullana sp., Enhydrosoma sp., and Onychoeamptus mohammed (Blanchard and Richard)); only nematode/ P. wellsi ratios were significantly affected by PAH. High-PAH treatments also lead to a higher proportion of females in P. wellsi and Coullana sp. This effect was only observed from Day 7 on and is interpreted as an indication of disproportionately high mortality of males. Collectively, our data demonstrate that relatively low-level PAH contamination may cause many ecologically important impacts on copepod community structure that may not be detected at the level of higher taxon.

Avoidable mortality. The case of the North border of Mexico, 1980-1990

When the death causes are understood as a result of morbility process that may have been avoided with different kinds of economic, social and welfare services policies and the advance of scientific and technologic knowledges, there is clearly a structural determinism so that many population social sectors can't reach the "modern epidemiological patterns". This study used annual data bases of register death 1979-1991 brought by INEGI/DGE-SSA from five Mexican federal border entities. It were adjusted by Preston-Coale method and Life Tables were generated in 1980 and 1990. The percentage contributions of avoidable causes' groups by sex and age of the increases in the Expectation of Life (Ex) were calculated in the same years following Pollard's method. As result of this research, limited increments of Ex were found because of the permanence of high contribution of deaths, that may have been avoided (50%). Contrary to popular beliefs, Ex male diminished the difference compared with Ex female. Highest male mortality is explained even for this kind of causes, where accidents and violence deaths are bringing high percentages of total mortality.