Wayfinding skills decay in old age, more so for wayfinding in an allocentric than an egocentric reference frame. This study investigates whether wayfinding deficits of schoolchildren mimic those of older adults. Schoolchildren were tested on two wayfinding tasks: one could only be mastered in an allocentric, and the other only in an egocentric reference frame. The results were compared with those from a previous study of young and older adults who had been tested on the same two wayfinding tasks. It was found that wayfinding performance improved somewhat from school age to young adulthood and that this improvement proceeded more or less in parallel for the allocentric and the egocentric tasks. It was further found that wayfinding performance decayed from young to older adulthood and that this decay was more dramatic for the allocentric than for the egocentric task. This pattern of findings does not support the hypothesis that the wayfinding performance of schoolchildren mimics that of older adults.

In social insects such as the honey bee, the quality of drones at the time of their emergence can affect their maintenance in the colony until maturity. Body mass, wing size and wing asymmetry of emerging honey bee drones were measured and correlated with their life span in the colony and compared between individuals reaching maturity or not. The life span of drones differed among colonies in which they were maintained after emergence but not between colonies in which they were reared. More drones heavier at emergence reached sexual maturity at 15 days and had a longer life span compared with light-weight drones of lower mass. The size and symmetry of drone forewings was not correlated with their life span. Our results suggest that body mass at emergence is a good predictor of drone survival in the colony.

Presently, about 12% of the population is 65 years or older and by the year 2030 that figure is expected to reach 21%. In order to promote the well-being of the elderly and to reduce the costs associated with health care demands, increased longevity should be accompanied by ageing attenuation. Energy restriction, which limits the amount of energy consumed to 60–70% of the daily intake, and intermittent fasting, which allows the food to be available ad libitum every other day, extend the life span of mammals and prevent or delay the onset of major age-related diseases, such as cancer, diabetes and cataracts. Recently, we have shown that well-being can be achieved by resetting of the circadian clock and induction of robust catabolic circadian rhythms via timed feeding. In addition, the clock mechanism regulates metabolism and major metabolic proteins are key factors in the core clock mechanism. Therefore, it is necessary to increase our understanding of circadian regulation over metabolism and longevity and to design new therapies based on this regulation. This review will explore the present data in the field of circadian rhythms, ageing and metabolism.

Spotted knapweed (Centaurea maculosa Lam. # CENMA) communities were sampled to determine the relationship between age and the number of root rings, and the population age structure. Spotted knapweed taproots add one ring of secondary xylem annually. In 1984, populations were expanding with high densities of individuals in the early age classes, followed by a steady decline in the older classes. In 1985, the majority of the individuals in knapweed populations were in the older age classes. This change in the population age structure was attributed to high mortality among the young age classes due to a drought in 1985. The maximum age class at the sites ranged from 5 to 9 yr. The percentage of plants with floral stalks increased with age to a peak of 75% in the fifth year in 1984 and in the seventh year in 1985.

The life history and digestive α-amylase activity of the Angoumois grain moth, Sitotroga cerealella Olivier (Lepidoptera: Gelechiidae) were studied on six wheat cultivars (Arg, Bam, Nai 60, Pishtaz, Sepahan and Shanghai) at 25 ± 1°C, relative humidity of 65 ± 5% and a photoperiod of 16:8 (L:D) h. A delay in the developmental time of S. cerealella immature stages was detected when larvae were fed on cultivar Sepahan. The maximum survival rate of immature stages was seen on cultivar Bam (93.33 ± 2.10%), and the minimum rates were on cultivars Nai 60 (54.66 ± 2.49%) and Sepahan (49.33 ± 4.52%). The highest realized fecundity and fertility were recorded for females which came from larvae fed on cultivar Bam (93.30 ± 2.10 eggs/female and 91.90 ± 3.10%, respectively); and the lowest ones were observed for females which came from larvae fed on cultivar Sepahan (49.30 ± 4.50 eggs/female and 67.4 ± 11.1%, respectively). The heaviest male and female weights of S. cerealella were observed on cultivar Bam (2.97 ± 0.02 and 4.80 ± 0.01 mg, respectively). The highest amylolytic activity of the fourth instar was detected on cultivar Bam (0.89 ± 0.04 mg maltose min−1), which had the maximum mean hundred-wheat weight (5.92 ± 0.19 g). One α-amylase isozyme was detected in the midgut extracts from the fourth instar larvae fed on different wheat cultivars, and the highest intensity was found in larvae fed on cultivar Bam. Correlation analyses showed that very high correlations existed between the immature period, fecundity and fertility on one side and inhibition of α-amylase, soluble starch content and hundred-wheat weight on the other. According to the obtained results, cultivar Sepahan is an unfavorable host for the feeding and development of S. cerealella.

Using data available from the literature, patterns of biomass, production and productivity of sandy-beach macrofauna populations were examined, considering environmental (temperature, exposure, grain size and beach slope) and biological variables (life span and mean body mass) and feeding and taxonomic groups. A total of 102 estimates of both production and biomass and 105 estimates of P/B ratios were collected from 52 studies carried out between 42°46′S and 54°05′N, for 83 sandy-beach macrofauna populations. The negative relationship between P/B ratio and beach slope for the supralittoral amphipods agrees with the Habitat Safety Hypothesis, according to which these forms would show higher mortality in dissipative than in reflective beaches. The observed higher production of filter-feeders in exposed than in sheltered beaches suggests that more food is available for filter-feeders in exposed beaches. The higher production of filter-feeders (represented by bivalves and decapods), than of scavengers/predators (peracarids and gastropods) showed the importance of filter-feeders in the food web of sandy beaches. The P/B ratios were strongly related to life span, but weakly or not related to the mean body mass. The high amphipod P/B ratio was attributed to the short life span of these crustaceans; conversely, gastropods showed the lowest P/B ratio, in accordance with their longer life span. The observed differences in biomass, production and P/B ratios within crustaceans and molluscs were attributed to differences in life-history traits and feeding mode.

Physical activity is influenced by genetic factors whose expression may change with age. We employed an extension to the classical twin model that allows a modifier variable, age, to interact with the effects of the latent genetic and environmental factors. The model was applied to self-reported data from twins aged 19 to 50 from seven countries that collaborated in the GenomEUtwin project: Australia, Denmark, Finland, Norway, Netherlands, Sweden and United Kingdom. Results confirmed the importance of genetic influences on physical activity in all countries and showed an age-related decrease in heritability for 4 countries. In the other three countries age did not interact with heritability but those samples were smaller or had a more restricted age range. Effects of shared environment were absent, except in older Swedish participants. The study confirms the importance of taking age effects into account when exploring the genetic and environmental contribution to physical activity. It also suggests that the power of genome-wide association studies to identify the genetic variants contributing to physical activity may be larger in young adult cohorts.

The Tristan klipfish, Bovichtus diacanthus, an endemic species at Tristan da Cunha Island was successfully aged using whole sagittal otoliths. The annulation pattern was clear, resulting in an alternating combination of opaque and translucent zones that form an annulus. Although sampling limitations did not allow direct validation of annual ring deposition, most otoliths showed a translucent edge, perhaps suggesting that the deposition of translucent zones is a synchronous process which takes place in winter coincident with the spawning season. The reliability of ageing methodology was supported by the good agreement between readings. The maximum age was estimated to be five years in females and four years in males. In order to increase the small number of direct readings, the length at age was back-calculated for each fish by fitting growth curves. The resulting growth of B.diacanthus was described by the von Bertalanffy growth model, as summarized by the following parameters: L∞ = 207.1 mm TL, k = 0.49 per year, and t0 = 0.04 years. The size at which 50% of the population spawns for the first time was c. 147 mm, corresponding to 2.5 years of age.

An assumed fixed maximum life span was involved in a much publicized prediction of a compression of morbidity in late life. The maximum life span has major weaknesses as a measure. The “usual life span“, or age to which 1.0% of a birth cohort survives, is suggested as a more useful measure.

Statistics were derived from recent United States and Canadian censuses on the age above which 1.0% of the population is contained, from recent United States and Canadian mortality data on the age above which 1.0% of the deaths were reported, and from recent Canadian life tables on the age to which 1.0% of a cohort would survive. These statistics suggest that the usual life span increased at least 2 years in the 1960–1980 period in North America.

Previous research on activity patterns of the elderly has relied on survey and interview methods which have depended on special measures and the long term memory of the respondents. This paper examines the use of time budgets in studying changing activity patterns across the life span. The independent variables of interest in this analysu were age, sex, marital status, education, and whether or not the individual lives alone. The dependent variable was the activity patterns of the individual. Results indicate that only age, of the factors considered here, endured significance across all comparisons.

We give a simpler and refined proof of some blow-up results of smooth solutions to the Cauchy problem for the Navier–Stokes equations of compressible, viscous and heat-conducting fluids in arbitrary space dimensions. Our main results reveal that smooth solutions with compactly supported initial density will blow up in finite time, and that if the initial density decays at infinity in space, then there is no global solution for which the velocity decays as the reciprocal of the elapsed time.

Three consecutive generations of the oval squid, Sepioteuthis lessoniana, were cultured between October 2000 and May 2002 to investigate the life history of this species. Starting with the parental generation (wild-caught sub-adult squid from Tokushima Prefecture, Japan), we successfully obtained first and second generations. Life span and maturation of cultured oval squid and wild oval squid caught from the same habitat during April 2001 through to March 2002 were compared. Captive squid matured earlier and had a shorter life span (189–247 days) than the wild-caught squid (approximately one year) but reached an equivalent final body size. More ova were found in the oviducts of cultured females than in the oviducts of wild-caught females. Ultimately, collapse of the culture population was mainly due to the low rate of embryonic development of spawned ova, which might have resulted from the abnormal arrangement of ova in egg cases produced by later generations of females.

Growth increments in statoliths of Idiosepius paradoxus were observed for aging analysis. The rate of increment formation was examined by staining the statoliths with tetracycline at 5–14 d intervals. In 6 of 16 specimens, increments formed daily, but in the other specimens, increments formed less than one per day. The maximum number of increments observed in males and females were more than 150 and 140, respectively, suggesting a life span of ≥150 and ≥140 d. During the cool season (from November to April), the dorsal mantle length (DML) and the number of increments gradually increased. Specimens collected in June showed bi-modal patterns in DML and the number of increments. Only small specimens were collected from August to October. These results suggest that two generations alternately occurred in the cool season and in the warm season.

A microcontrolled fish tag which records post-tagging life span, was developed and tested as a prototype. The method of making the tag and the results of tank test trials on chinook salmon (Oncorhynchus tshawytscha) and field trials on chum salmon (Oncorhynchus keta) are presented. This tag was specifically designed to measure survey life (SL) but may have other applications. Survey life is an essential component for area-under-the-curve (AUC) estimation of Pacific salmon (Oncorhynchus spp.) spawning escapements. Accurate escapement estimates are critically important for salmon fisheries management and science. However, AUC spawner estimates must often employ average SL values from historic rather than year-specific studies because direct estimates of SL can require extensive and costly tag-recapture programs. Using assumed SL values can introduce serious bias in population estimates, therefore alternative methods of determining annual SL are important. In this study, the new tag estimated SL by measuring the elapsed time from tagging until the fish came to rest permanently on its lateral or dorsal surface. Details on how to construct the tag are provided so that researchers will be able to make their own.

Senescence is the internal physiological deterioration that accompanies advancing age. Evolutionary hypotheses predict that rates of senescence should vary directly with extrinsic mortality and inversely with fecundity. If so, naked mole-rats (Heterocephalus glaber) should live a long time (senesce slowly) because in nature they inhabit heavily protected burrows, and large, old breeding females make disproportionate reproductive contributions. In addition H. glaber has an exceptionally low metabolic rate, which may reduce oxidative stress. We have maintained naked mole-rats in captivity since 1974. Here we report that individuals can live a very long time: many are alive after more than 20 years and some are 26 years old (and counting). Although we do not yet know how long naked mole-rats can live, they already are older than the maximum longevity of all but one of 156 rodent species that have been maintained in captivity from birth to death.

Elevated CO2 increases root growth and fine (diam. [les ]2 mm) root growth across a range of species and experimental conditions. However, there is no clear evidence that elevated CO2 changes the proportion of C allocated to root biomass, measured as either the root[ratio ]shoot ratio or the fine root[ratio ]needle ratio. Elevated CO2 tends to increase mycorrhizal infection, colonization and the amount of extramatrical hyphae, supporting their key role in aiding the plant to more intensively exploit soil resources, providing a route for increased C sequestration. Only two studies have determined the effects of elevated CO2 on conifer fine-root life span, and there is no clear trend. Elevated CO2 increases the absolute fine-root turnover rates; however, the standing crop root biomass is also greater, and the effect of elevated CO2 on relative turnover rates (turnover[ratio ]biomass) ranges from an increase to a decrease. At the ecosystem level these changes could lead to increased C storage in roots. Increased fine-root production coupled with increased absolute turnover rates could also lead to increases in soil organic C as greater amounts of fine roots die and decompose. Although CO2 can stimulate fine-root growth, it is not known if this stimulation persists over time. Modeling studies suggest that a doubling of the atmospheric CO2 concentration initially increases biomass, but this stimulation declines with the response to elevated CO2 because increases in assimilation are not matched by increases in nutrient supply.

The life history of Amblyseius fustis (Pritchard and Baker) was studied in the laboratory at a fluctuating temperature and relative humidity ranging from 24.4 to 28.0°C and 55.5 to 75.6%, respectively. The developmental stages consist of egg, larva, protonymph, deutonymph and adult. The life cycle, from egg to adult of both male and female was about 8 days, while longevity was about 19.2 days. Mated female laid an average of 18.8 eggs. There was no significant difference in the longevity and fecundity of predators fed on different life stages of the host. The proportion of male to female in the progeny of mated females was 1:4.

A. fustis has a shorter developmental period and lives longer than its prey, but the latter is more fecund (26.9 eggs/♀) and has a higher proportion of females in its progeny (1:4.8). The shorter developmental period and the longer life span of the predator are likely to offset the higher fecundity of the prey.

This paper examines the distribution of deaths in life tables for the population of England and Wales as a means of exploring the way in which the length of life is steadily advancing. To assess the possibility for future extension, some extreme assumptions are made about the reduction in mortality rates for certain causes. A distinction is made between ‘anticipated' deaths and ‘senescent' deaths, the latter group falling within bounds either side of a terminal peak in the distribution of deaths by age. For males, the extreme assumptions yield a peak at age 86 with some 85 per cent of deaths within the senescent area. For females, the peak is at about age 92 with 90 per cent of deaths in the senescent area.