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PubMed2003

Association between the HLA-DR alleles and longevity: a study in Sardinian population.

Human longevity may be correlated with optimal functioning of the immune system, suggesting that genetic determinants of longevity also resides in those polymorphisms for the immune system genes that regulate immune responses as histocompatibility (HLA) antigens. However, conflicting results have been obtained. Some well planned and designed association studies performed in Caucasians suggest that longevity is associated with positive selection of alleles (i.e. HLA-DR11) or haplotypes (i.e. HLA-B8,DR3) that confer resistance to infectious diseases, respectively, via peptide presentation or via antigen non-specific control of immune response. Association studies are subjected to a number of possible confounding factors, the homogeneity of the population in term of geographical origin among others. Because of the lack of large-scale heterogeneity, the Sardinians represent a suitable population for association studies addressed to dissect the complex traits as longevity. Thus, we have evaluated, by the amplification refractory mutation system/polymerase chain reaction, HLA-DR frequencies in 120 centenarians (79 women and 41 men) and 86 controls (53 women and 33 men) from Sardinia, to validate, in this very homogeneous population, the associations between HLA alleles or haplotypes and longevity observed in other Caucasoid populations. No significant differences were obtained by analysing the differences between Centenarians and controls except for HLA-DRB1*15 that was increased in centenarians. However, the significance was not maintained by multiplying P values for the number of alleles under study. Thus, in Sardinian centenarians, we were not able to confirm the findings observed in the well planned and designed studies performed in other Caucasoid populations. Besides, HLA HFE gene polymorphisms have been recently demonstrated to be associated with longevity in the Sicilian population but not in Danish one. On the whole these findings clearly show that HLA/longevity associations are population-specific, being heavily affected by the population-specific genetic and environmental history. So, in our opinion, HLA genes might be considered survival genes not longevity genes.

Aged↗
PubMed2004

Relationships between longevity and linear type traits in Holstein cattle population of Southern Africa.

Relationships between longevity and linear type traits were estimated using data on 34,201 cows with lifetime information and linear type scores. The longevity trait considered was the number of lactations initiated and the linear type traits were rump height, body depth, angularity, rear udder height, fore udder attachment, udder depth, fore teat placement and fore teat length. Fixed effects included in the models were herd year, season of calving and herd-date of classification-classifier and days in milk. Age at first calving and age at classification were included as linear and quadratic covariates. Heritability estimates were low for longevity and moderate for most type traits except rump height and fore teat length. All the phenotypic correlations between longevity and the linear type traits were slightly positive (0.01 to 0.09) except the relationships with rump height and fore teat length which were -0.01 and -0.02, respectively. Genetic correlations between longevity and udder traits as well as angularity were moderate to high and positive (0.22 to 0.48). The only notable negative genetic correlations were longevity with body depth and fore teat length (-0.15 and -0.07, respectively). The genetic correlations suggest that selection for udder traits and angularity should improve longevity in the Holstein cattle population.

Age Factors↗
PubMed1993

Larval regulation of adult longevity in a genetically-selected long-lived strain of Drosophila.

Our previous work has shown that the major genes involved in the expression of the extended-longevity phenotype are located on the third chromosome. Furthermore, their expression is negatively and positively influenced by chromosomes 2 and 1, respectively. In this report we show that the expression of the extended-longevity phenotype is dependent on the larval environment. A controlled chromosome substitution experiment was carried out using a strain selected for long life (L) and its parent (R) strain. Twenty different combinations of the three major chromosomes were conducted and their longevities were determined under both high (HD) and low (LD) larval density conditions. The extended-longevity phenotype was only expressed under HD conditions. The chromosome interactions were not apparent under LD conditions. Density-shift experiments delineate a critical period for expression of the extended-longevity phenotype, extending from 60 h after egg laying (AEL) to 96 h AEL, during which the developing animal must be exposed to HD conditions if the extended-longevity phenotype is to be expressed. The change from HD to LD conditions is accompanied by statistically significant increases in body weight. The possible role of a dietary restriction phenomenon is examined and the implications of these findings discussed. It is now apparent, however, that the extended-longevity phenotype in Drosophila is a developmental genetic process.

Animals↗
PubMed2003

Early programming of adult longevity: demographic and experimental studies.

It is supposed that longevity might be programmed by early life exposures. We had carried out demographic and experimental researches for the examination of the possibility of longevity programming. In demographic study, the recorded deaths in Kiev (Ukraine) between 1990 and 2000 (51,503 men and 50,131 women) were used. Age at death was strongly associated with month of birth. Subjects born in the middle of year (April-July) had the lowest longevity. Increasing longevity was observed with each successive birth-month in the second half of the year, with a peak longevity for births in December. To research of the mechanisms responsible for longevity programming, study of adult D. melanogaster DNA repair capacity after irradiation at the egg stage was carried out, using marker such as DNA strand breaks. Insects irradiated in low doses (0.50 and 0.75 Gy) had extended life span and increased stability to S1 nuclease treatment. The probable explanation of observed postponed effects might be the long-term modulation of certain (possibly repair) genes activity. We hypothesize that life-extending effects of different anti-aging treatments might be a consequence of their unspecific (hormetic) action, rather then specific (geroprotector) action on the some aging-related processes, and induction an "transcriptional reprogramming" may be a key mechanism of the longevity programming and artificial life extension.

Aged↗
PubMed2003

Communication between identical twins: health behavior and social factors are associated with longevity that is greater among identical than fraternal U.S. World War II veteran twins.

BACKGROUND: Longevity is greater for identical twins than for fraternal twins from the same population. Factors that are explanatory for this difference are not known. METHODS: Multivariate survival analysis is applied to current mortality data for 26,974 male twins with known zygosities of the National Academy of Science-National Research Council World War II Veteran Twins Registry, and this analysis is applied to their health and social behavior and personal histories, as collected from two survey questionnaires distributed in 1967 and 1983 (with 14,300 and 9475 responses received, respectively). To explain this difference in longevity, social, health, and personal history factors are evaluated for associations with longevity. RESULTS: Survival functions of identical and fraternal twins differed significantly (p<.0001). Median lifetimes were 82 years for identical and 80.5 years for fraternal twins. The correlation between lifetimes of identical twin partners was greater than that of fraternal twins. For identical but not for fraternal twins, the risk of mortality was significantly lower for twin partners who communicated 1 or more times per month, compared with those who communicated less frequently (relative risk.80, 95% confidence interval 0.68-0.94, p=.008, with control for other factors associated with longevity: smoking, exercise, a current marriage, living with both parents until age 15 or older, and having a live co-twin). Distributions of communication, exercise level, and smoking prevalence were more beneficial with regard to longevity for identical than for fraternal twins as a group. CONCLUSIONS: Frequent communication between identical but not fraternal twin partners, and both level of exercise and prevalence of smoking, distributed more beneficially in terms of longevity for identical compared with fraternal twins, are explanatory for the greater longevity of identical than fraternal twins.

Aged↗
PubMed1998

Assessing the effects of deprenyl on longevity and antioxidant defenses in different animal models.

Among many pharmaceuticals that have been tested for their effects on longevities of different animal rodents, deprenyl is unique in that its effects on longevity has been tested in at least four different animal species by independent research groups and that the effect has been postulated to be due to its effect of raising such antioxidant enzyme activities as superoxide dismutase (SOD) and catalase (CAT) in selective brain regions. Thus far, in all four species of animals examined (rats, mice, hamsters, and dogs), a positive effect was demonstrated, although the extent of its effect is quite variable. Our group has examined the effect on longevities in rats and mice and on antioxidant enzymes in rats, mice, and dogs. Although in rats of both sexes, we have obtained positive effects on longevity, two studies with different doses in mice did not reveal a significantly positive effect. We have observed, however, significantly positive effects on SOD (in Cu, Zn-, and Mn-) as well as CAT (but not glutathione peroxidase) activities in the brain dopaminergic system such as in the S. nigra and striatum (but not in hippocampus) in all rats, mice, and dogs, although the effects were quite variable, depending on the doses used. In mice, however, a long-term administration (3x/w, 3 months) caused a remarkable decrease in the magnitude of activity as well as a narrowing of the effective dose range, which may explain a relatively weak effect of the drug on mouse longevity. Further, a recent study on aging beagle dogs by Ruehl et al. showed a remarkable effect on longevity, which agrees with our SOD study in dogs. Although deprenyl has been claimed to have several other effects, such as a radical scavenging effect and a neuroprotective effect, past reports on its effects on longevities and antioxidant defenses are compatible with the notion that the drug prolongs the life span of animals by reducing the oxidative damage to the brain dopaminergic system during aging. Further, our studies on F-344 rats as well as a dog study by Ruehl et al. suggest that the drug may at least partially prolong the life span of animals by enhancing immune system function and preventing tumor development in animals.

Animals↗
PubMed1979

An attempt to select for increased longevity in Drosophila melanogaster.

Eight generations of selection towards a higher longevity were made in a wild strain of Drosophila melanogaster. Two control lines were also observed. Absolutely no response to selection was obtained whilst a major increase in longevity occurred between F2 and F4 in the three lines under observation. It is shown that the major increase in longevity is due neither to genetic drift, nor to changes in classical environmental conditions. The absence of response to selection is demonstrated to be due neither to a too low selection differential, nor to the absence of genetic variability in the strain, nor to inaccuracy in the measurements, nor to recurrent reproduction at an old age. The impossibility to select towards a higher longevity and the total absence of relation between parental and offspring longevities demonstrate that the very large phenotypic variability displayed by longevity in wild strains of D. melanogaster does not depend on a precise set of specific genes or polygenes with additive action. The results are briefly discussed in relation with inbreeding depression and heterosis for longevity and with similar results obtained in experiments of selection for duration of development.

Animals↗
PubMed2006

Parental investment, late reproduction, and increased reserve capacity are associated with longevity in humans.

Throughout the living world trade-offs between reproductive success and longevity have been observed. In general, two extremes of life history patterning are reported, r- and K-selected species. The latter tend toward larger body sizes, few offspring from any one pregnancy, few offspring over the female reproductive span, longer life spans, and greater parental investment (PI: all efforts and expenses associated with the production, gestation, post-natal care, feeding, and protection of young) (e.g., whales, elephants, hominids). r-selected species tend toward smaller body size, multiple births/litters per pregnancy, female production of many gametes and offspring over the life span, and low levels of PI (e.g., most plants, insects, mice). These differences have significant influences on physiological variation among human populations. Across human samples, reproductive success (RS: the number of offspring successfully birthed and reared to reproductive age) has been reported to vary positively, negatively, and not at all with longevity of women. This complexity may be in part due to the fact that both early-life and late-life fecundity are associated with longevity in women, while total parity seems a poor gauge of female longevity in humankind. Large variations in associations of RS with longevity in women suggest that multiple factors may confound this association. One confounding factor is that among women, RS is largely determined not by fecundity, but by the quality of PI available to offspring. Among modern humans, PI is more complex, longer lasting (both relatively and absolutely), and extensive than for any other mammal. This suggests that modern human life history is a reflection of the co-evolution of longevity and extensive PI as part of our species' biocultural evolution. The need for long-term PI has greatly shaped human physiological variation and patterns of longevity.

Adolescent↗
PubMed2004

Phenotypic relationships between longevity, type traits, and production in Chianina beef cattle.

Longevity is an increasingly important trait in beef cattle. Increased longevity decreases costs for the farmer and increases revenue. The objective of this research was to investigate the phenotypic relationship between type traits and longevity in Chianina beef cattle, and the relationship between production and longevity, to analyze the effect of voluntary culling. Data included records on reproductive, productive, and type traits provided by the National Association of Italian Beef Cattle Breeders from 6,395 Chianina cows. The average length of productive life was 1,829 d. The herd-year had a strong effect on the risk of culling. The effects of 22 type traits were analyzed. All the muscularity traits analyzed were highly significant (P < 0.01) and as a group had the largest effect on longevity, followed by dimension, refinement, and leg traits. Cows that calved before 35 mo of age had a lower probability of being culled than cows calving after 35 mo of age. Variation in herd size had a strong effect on risk ratio, with lower risk for intermediate classes. Cows with approximately one calf per year remained in the herd longer than did cows with fewer calves. Straight-legged animals had a 59% greater probability of being replaced than cows with a moderate angle to the hock, whereas sickle-legged animals had only a 3% higher probability of being culled than average cows. Udder conformation had no effect on longevity. In summary, results of this study indicate that herd-year effects and muscularity traits were the most important factors for longevity for Chianina cows among the factors studied.

Age Factors↗
PubMed1988

Genetic aspects of longevity in Angus and Hereford cows.

Thirty years and 23 yr of life history data from a Hereford herd in Arizona and an Angus herd in Wyoming, respectively, were analyzed. Longevity averaged 4.21 +/- .06 for years from first calving to disposal (FST), 7.40 +/- .06 for years from birth to disposal (AGE) and 3.46 +/- .06 for lifetime number of calves weaned (NUM) in Herefords and 4.49 +/- .13 (FST), 6.68 +/- .12 (AGE) and 3.66 +/- .11 (NUM) in Angus. In the Hereford herd, heritability estimates for traits measuring longevity, estimated from daughter-dam regression and paternal half-sib analyses, ranged from .16 to .26. In the Angus herd, heritability estimates from daughter-dam regression ranged from .03 to .05. In the Hereford herd, genetic correlations of birth weight and weaning weight with longevity, from daughter-dam regression, were negative and generally of low magnitude, whereas genetic correlations between weaning condition score and longevity were positive and moderate. Analogous estimates from paternal half-sib analyses all were positive and moderate to high. Phenotypic correlations between early life traits and longevity traits in Herefords all were near zero. In the Angus herd, curves for age-specific survivorship and age-specific survival rate varied markedly among sires. This study suggested the existence of moderate genetic variation for longevity traits in beef cattle. None of the traits expressed early in life that were examined would, however, be reliable predictors of genetic or phenotypic merit for longevity.

Animals↗
PubMed2005

Phenotypic associations between traits other than production and longevity in New Zealand dairy cattle.

A proportional hazards model was used to investigate the phenotypic effect of traits other than production (TOP) on true and functional longevity across purebred and crossbred Holstein-Friesian and Jersey dairy cattle in registered and commercial herds in New Zealand. The hazard function was described as the product of a baseline hazard function and the time-independent effects of age at first calving, heterosis, proportion of breed, period of last calving relative to herdmates, and TOP; a time-dependent effect of herd-year was also included. The influence of TOP on functional longevity was assessed by adjusting true longevity for the time-independent effects of production values as well as the time-dependent effects of deviation of milk, fat, and protein yield within contemporary group. All analyses were stratified by breed, and separate analyses were carried out for registered or commercial herds. All TOP were significantly related to true and functional longevity. Obvious differences existed in the relative influence of individual TOP on longevity in registered or commercial herds. Of the individual TOP describing the physical characteristics of the cow, the udder-related TOP exhibited the largest influence on functional longevity. Farmer opinion explained the largest proportion of variation in true and functional longevity among cows. In commercial herds, the risk of culling in cows with very low farmer opinion was 1.5 to 2.0 times that in cows with average or high farmer opinion.

Animals↗
PubMedDate not supplied

Lower 24-h blood pressure regimen in subjects with a familial genealogy of longevity.

OBJECTIVE: This study investigates the 24-h blood pressure (BP) pattern in longevous subjects and their progeny, in order to validate the hypothesis that the human beings who live beyond their longest expectancy of life should be protected from developing hypertension. Such a characteristic feature is supposed to be a biological aspect of human longevity which can be transmitted to the progeny. MATERIALS AND METHODS: The study was carried out on 92 elderly subjects, (45 M, 47 W, 76-102 years), and 28 firstborn descendants of the first (7 M, 7 W, 36-55 years) and second (7 M, 7 W, 16-26 years) generation, in clinical health. The control subjects were 308 clinically healthy individuals (154 M, 154 F, 16-75 years) of the common population, stratified by age. RESULTS: The longevous subjects were found to show a diastolic daily mean level less pronounced than expected, according to the BP age-related trend in the common population. Both the children and grandchildren of the longevous subjects were seen to show a systolic and diastolic daily mean level significantly less pronounced than in their coeval subjects of the common population. CONCLUSIONS: Because of the unexpected lower diastolic BP daily mean level in the very old subjects, the hypothesis that the longevous subjects might be protected from developing hypertension via the arteriolar vasoconstriction seems to be confirmed. Because of the lower systolic and diastolic BP in young and adult subjects with a positive familiarity for longevity, the hypothesis that the hemodynamic protection from senile hypertension might be an inheritable biological feature of the longevity seems to be acceptable.

Adolescent↗
PubMed1998

Evolution, mutations, and human longevity: European royal and noble families.

The evolutionary theory of aging predicts that the equilibrium gene frequency for deleterious mutations should increase with age at onset of mutation action because of weaker (postponed) selection against later-acting mutations. According to this mutation accumulation hypothesis, one would expect the genetic variability for survival (additive genetic variance) to increase with age. The ratio of additive genetic variance to the observed phenotypic variance (the heritability of longevity) can be estimated most reliably as the doubled slope of the regression line for offspring life span on paternal age at death. Thus, if longevity is indeed determined by late-acting deleterious mutations, one would expect this slope to become steeper at higher paternal ages. To test this prediction of evolutionary theory of aging, we computerized and analyzed the most reliable and accurate genealogical data on longevity in European royal and noble families. Offspring longevity for each sex (8409 records for males and 3741 records for females) was considered as a dependent variable in the multiple regression model and as a function of three independent predictors: paternal age at death (for estimation of heritability of life span), paternal age at reproduction (control for parental age effects), and cohort life expectancy (control for cohort and secular trends and fluctuations). We found that the regression slope for offspring longevity as a function of paternal longevity increases with paternal longevity, as predicted by the evolutionary theory of aging and by the mutation accumulation hypothesis in particular.

Adult↗
PubMed2001

A randomized study on the effects of pacemaker programming to a lower output on projected pulse generator longevity.

The programmability of cardiac pacemakers enables the physician at follow-up to adjust the pacing pulse under consideration of the 100% safety margin with respect to the individual pacing threshold. The purpose of reducing the output is to prolong pacemaker longevity. The aims of this prospective, randomized trial were to compare the effects of nominal output versus a lower output on projected pacemaker longevity in single and dual chamber pacemakers. The secondary aim was to assess how many patients can be programmed to 2.5 V/0.4 ms instead of the nominal 3.5-V setting with > or = 100% safety margin. The patients received the same types of VVI or DDD pacemakers that were connected in the ventricle to the steroid-eluting, high impedance pacing lead. At the 3-month follow-up, patients with ventricular pacing thresholds < or = 0.15 ms at 2.5-V pulse amplitude were randomized to 3.5 V or 2.5 V amplitude at 0.4-ms pulse duration. Lead function and projected device longevity were assessed with the pacemaker's telemetry 6 and 12 months after implantation. Of patients implanted with a VVI pacemaker, at the 3-month follow-up, 3 patients had pacing thresholds > 0.15 ms at 2.5 V and 139 patients could be randomized. A reprogramming to a higher output was necessary in one patient. The mean percentage of ventricular pacing was about 40% throughout the study time. The programming to 2.5-V output resulted in an insignificant increase of device longevity from 117.9 +/- 18.7 months in the nominal group to 123.7 +/- 11.9 months at the 12-month follow-up (P = 0.16). Of patients implanted with a DDD pacemaker, 166 patients underwent randomization. The mean percentage of ventricular pacing was 85% in the ventricle and 35% in the atrium. The 2.5-V setting significantly prolonged pacemaker longevity from 98.1 +/- 21.3 to 112.0 +/- 13.6 months (P < 0.0001). In three (1%) patients a late increase of the pacing threshold was observed. Due to the low ventricular pacing thresholds, the 2.5-V/0.4-ms setting provided, 3 months after implantation, a > or = 100% safety margin in 99% of the patients. Programming to a lower output slightly increased projected pacemaker longevity compared to the nominal 3.5-V setting. Longevity increasedfor 5% in patients with single andfor 14% in dual chamber pulse generators.

Aged↗
PubMed1992

Improvement of Longevity and Viability of Sperm Cells Isolated from Pollen of Zea mays L.

Our previous studies showed that the common maize (Zea mays L.) sperm isolation medium (Brewbaker and Kwack salts in 0.44 m sucrose without buffering) caused cell lysis in vitro. In an attempt to remedy this situation, 6 sugars, 10 buffers, 5 pH values, and 3 membrane protective agents were screened to improve longevity and viability of isolated Zea mays sperm cells as estimated by hemacytometry and flow cytometry. Use of 0.55 m galactose in the isolation solution increased sperm yield by 2.5-fold compared with sucrose, and suspension of isolated sperm cells in the galactose solution gave the best longevity among the six sugars. Buffering the galactose solution with 2 mm 2-(N-morpholino)ethanesulfonic acid significantly improved longevity, whereas other buffers had no effect or decreased the longevity and/or viability. Among the five pH values tested (5.0, 6.0, 6.7, 7.0, and 8.0), pH 6.7 appeared to be optimal for maintenance of both longevity and viability. Screening of membrane protectants showed that cysteine caused a rapid decrease in cell viability and increased lysis, whereas dithiothreitol increased the cell numbers but lowered their viability. Addition of 0.1% bovine serum albumin increased cell numbers and viability, and about 70% of the cells remained viable after 72 h of suspension. Cell longevity and viability were also improved in 0.44 m sucrose when the solution was conditioned with 2-(N-morpholino)ethanesulfonic acid and bovine serum albumin. Use of 2-(N-morpholino)ethanesulfonic acid and bovine serum albumin inthe isolation and suspension medium significantly improved the viability and longevity of sperm cells isolated from Zea mays pollen.

Journal Article↗
PubMed2000

Lifetime reproductive success, longevity, and reproductive life history of female yellow baboons (Papio cynocephalus) of Mikumi National Park, Tanzania.

The relationship between longevity and lifetime reproductive success (LRS) was studied in free-ranging female baboons of Mikumi National Park, Tanzania. A severe population decline occurred between the 12th and 20th years of the study. The total sample consisted of 72 females born and reaching adulthood before the start of the population decline. There were 27 females who were adult at the start of the study and 45 who became adult within the 12 years prior to the decline. The subjects were studied until all 72 were dead and all of their offspring were either dead or at least six years old; this took 24 years. The relationship of longevity to LRS was statistically significant for the total sample and for both sub-samples, with 70% of the total variance in LRS accounted for by longevity. Longevity was linked to LRS via a chain of statistically significant relationships: The longer the life span, the longer the reproductive life; the longer the reproductive life, the more offspring produced; the more offspring produced, the higher the LRS. Mean LRS, life span, and reproductive longevity all differed between the two sub-samples. Since the sub-samples were time-linked to a population decline affecting longevity, either sub-sample separately would fail to reflect the broader picture. This illustrates the importance of appreciable sample sizes from long-term studies in helping understand the dynamics between life history estimates and ecological conditions in variable environments.

Animals↗
PubMed2006

Longevity differences among lines artificially selected for developmental time and wing length in Drosophila buzzatii.

We assessed the indirect response of longevity in lines selected for wing length (WL) and developmental time (DT). Longevity in selection lines was compared to laboratory control lines and the offspring of recently collected females. Wild flies (W lines), flies from lines selected for fast development (F lines), and for fast development and large wing length (L lines) outlived control laboratory lines (C lines) and lines selected for fast development and short wing (S lines). The decline in longevity in S lines is in line with the idea that body size and longevity are correlated and may be the result of the fixation of alleles at loci affecting pleiotropically the two traits under selection and longevity. In addition, inbreeding and artificial selection affected the correlation between wing length and longevity that occurs in natural populations of Drosophila buzzatii, suggesting that correlations between traits are not a perdurable feature in a population.

Aging↗
PubMed1989

Does genotypic sex have a direct effect on longevity?

Females of the human species live longer than males, and the longevity differential is probably not entirely explained by reasons which are presently obvious. Genotypic sex has long been suspected to affect longevity to the advantage of the female. Several recent findings about the X and Y chromosomes must be reckoned with in considering determinants of longevity which derive from genotypic sex. The advantages of having two X chromosomes are apparent, notwithstanding X-chromosome inactivation. Not only can some cells compensate for biosynthetic deficiencies of others, but also cell selection according to which X chromosome is active can occur during development according to cell viability and proliferative capacity. It has recently been observed that at least some genes on inactive X chromosomes are reactivated late in life. Details of the reactivation process must be studied to determine its significance and the effects of the process on late life survival. The recent mapping of the catalytic polypeptide of DNA-polymerase-alpha to the X chromosome calls attention to a new property of the genotype which could affect the basic ability of cells to proliferate. It is likely that this enzyme, perhaps in concert with DNA-polymerase-delta, is required for DNA replication, suggesting that two alleles for this enzyme and cell selection within the female phenotypic mosaic for DNA replication may provide a sex-linked determinant of cell proliferation which could be advantageous in late life. Much remains to be learned about the Y chromosome, although there are early results consistent with a determinant of longevity on that chromosome which operates to the male disadvantage and probably does not involve sex hormones. The genotype may be a significant determinant of longevity in humans even if it does not appear to be so in non-human animals, because causes of death are different. Determinants of longevity are based on susceptibility or vulnerability to the causes and diseases of mortality, and these differ in different species.

Female↗