Long-run trends of human aging and longevity

Over the last 200 years, humans experienced a huge increase of life expectancy. These advances were largely driven by extrinsic improvements of their environment (for example, the available diet, disease prevalence, vaccination, and the state of hygiene and sanitation). In this paper, we ask whether future improvements of life expectancy will be bounded from above by human life span. Life span, in contrast to life expectancy, is conceptualized as a biological measure of longevity driven by the intrinsic rate of bodily deterioration. In order to pursue our question, we first present a modern theory of aging developed by bio-gerontologists and show that immutable life span would put an upper limit on life expectancy. We then show for a sample of developed countries that human life span thus defined was indeed constant until the mid-twentieth century but increased since then in sync with life expectancy. In other words, we find evidence for manufactured life span.     

Life Span Extension in Humans Is Self‐Reinforcing: A General Theory of Longevity

This article proposes that longevity is not merely the result of an absence of mortality but a self‐reinforcing and positively selected life‐history trait in social species. It argues that a small increase in longevity is amplified as (1) reductions in mortality at young ages increase natural selection for mechanisms of maintenance and repair at all older ages as well as increasing the potential for intergenerational transfers; (2) intergenera‐tional transfers of resources from old to young increase fitness (e.g., through improved health, skill, and competitive ability) of the young and thus favor the presence of older individuals in a population; and (3) the division of labor increases both efficiency and innovation at all levels, resulting in increased resources that can be reinvested. This theory is framed around the longevity‐oriented question posed two decades ago by the ger‐ontologist George Sacher, “Why do we live as long as we do?,” rather than the more prevalent question today, “Why do we grow old?” The article describes the foundational principles and the main phases of a model for the evolution of longevity mediated through social organization, and applies the concept specifically to human populations.     

The implications of increased survivorship for mortality variation in aging populations

The remarkable growth in life expectancy during the twentieth century inspired predictions of a future in which all people, not just a fortunate few, will live long lives ending at or near the maximum human life span. We show that increased longevity has been accompanied by less variation in ages at death, but survivors to the oldest ages have grown increasingly heterogeneous in their mortality risks. These trends are consistent across countries, and apply even to populations with record-low variability in the length of life. We argue that as a result of continuing improvements in survival, delayed mortality selection has shifted health disparities from early to later life, where they manifest in the growing inequalities in late-life mortality.     

Reproductive history and mortality later in life: A comparative study of England and Wales and Austria

Does a woman's reproductive history influence her life span? This study explores the question with data from the contemporary female populations of England and Wales and Austria. It is the first comparative study to investigate the relationship between fertility and mortality late in life. We find similar patterns and age-specific trends of excess mortality in both populations: parity significantly influences longevity, as do both an early and a late birth. These differences in longevity are not explained by differences in educational or family status. The impact of a woman's reproductive history on her life span is small, however, compared to the influence of her level of education or family status.     

A host shift from wild blue cohosh to cultivated potato by the phytophagous ladybird beetle, Epilachna yasutomii (Coleoptera, Coccinellidae)

Life history traits of the phytophagous ladybird beetle Epilachna yasutomii were compared between a nonpest population feeding on wild blue cohosh and a pest population feeding on cultivated solanaceous crops, mainly potato. Newly emerged adults of the nonpest population entered diapause early in midsummer when blue cohosh withered, while adults of the pest population were found in tomato and eggplant fields until late autumn. The pest population had larger females, a higher population growth rate, a shorter larval developmental period, and reduced longevity of overwintered females, compared with the nonpest population. ANOVA indicated that all these life history traits were influenced by the food plant, and that the number of eggs laid per female and the longevity of overwintered females were also affected by the population type. These findings suggest that the life history pattern of E. yasutomii changed to high fecundity with a short life span from low fecundity with a long life span as a result of the host shift from wild blue cohosh to cultivated solanaceous crops. Received: May 22, 1998 / Accepted: January 13, 1999     

Longevity Advances in High‐Income Countries, 1955–96

The advance of life expectancy within high‐income countries from 1955 to 1996 is well represented by a straight‐line trend. This explains more of the variance on average, and in 19 of 21 high‐income countries, than logged or unlogged age‐standardized death rates. Change in life expectancy in individual countries over this period was partially predicted by a country's level relative to the rest of this group of high‐income countries and partially by a country's own prior rate of advance, with substantial convergence toward the group mean for both measures.     

Reproductive history and mortality later in life: a comparative study of England and Wales and Austria

Does a woman's reproductive history influence her life span? This study explores the question with data from the contemporary female populations of England and Wales and Austria. It is the first comparative study to investigate the relationship between fertility and mortality late in life. We find similar patterns and age-specific trends of excess mortality in both populations: parity significantly influences longevity, as do both an early and a late birth. These differences in longevity are not explained by differences in educational or family status. The impact of a woman's reproductive history on her life span is small, however, compared to the influence of her level of education or family status.     

A Realist View of Aging,Mortality, and Future Longevity

Differences in methodology and philosophy have led scientists analyzing the same mortality data to arrive at very different conclusions about the behavior of mortality trajectories, the nature of aging, and the future of human longevity. This note describes the authors’views on these issues, which taken together can be termed a “realist” position. In this view, life expectancy is unlikely to exceed an average of 85 years absent significant advances in the control of aging. We identify a number of myths that have been attached to our work: 1) Reaching an average life expectancy of 85 years is a pessimistic outlook for human longevity, 2) Species possess an intrinsic mortality schedule that cannot be modified by human intervention, 3) Realist scenarios of the future course of human longevity are based on notions of biological determinism, 4) Realists assert that there is an age beyond which there can be no survivors, 5) Hypothesized biological barriers to longer life spans have been scientifically studied and refuted, and 6) Realists claim that life expectancy at birth cannot exceed 85 years. In dispelling these myths, we hope to provide a more accurate representation of our school of biodemographic thought.     

Life tables for worker honeybees

Summary Life tables for worker honeybees covering all life span, and those for adults, were prepared for three seasonal cohorts,June bees, July bees andwintering bees. Survivorship curves forJune andJuly bees show a convex type being exceptional for insects, with relatively high mortality at egg and feeding larval stages and at later adult stage after most bees became potential foragers. Adult longevity greatly lengthens inWinteriing bees and survivorship curve drops approximately with the same rate. A remarkable similarity of survivorship curves for men and honeybees was demonstrated, apparently due to highly developed social care in both. Some comments were given on mortality factors. The importance of life tables for population researches was shown by applying our result to the population growth curve made byBodenheimer, based upon the data byNolan. At the asymptote of the uncorrected curve, the ratio of total population estimated by uncorrected curve to that by corrected curve reaches about 3∶2. Contribution No. 821 from the Zoological Institute, Faculty of Science, Hokkaido University, Sapporo, Japan. Contributions from JIBP-PT No. 45. This study was in part supportod by a grant in aid from the Ministry of Education for the special project research, “Studies on the dynamic status of biosphere.” Population and bioeconomic studies on the honeybee colonies. II. We express our sincere thanks to Dr. YosiakiIt?, National Institute of Agricultural Sciences, Tokyo, for his kind stimulation and advices to the present work.     

Increase in common longevity and the compression of mortality: the case of Japan

This study shows a strong increase in the modal age at death (M) in Japan over a period of 50 calendar years, accompanied by a clear decrease in the standard deviation of ages at death above M (SD(M+)) until the 1990s for men and the mid-1980s for women. For the most recent periods SD(M+) appears to have stopped decreasing, even though M has continued to increase linearly. This stagnation in SD(M+) has been accompanied by stagnation in q(M). The number of deaths at M (d(M)) and the number of deaths at and above M (d(M+)) have increased, but significantly more slowly since the period 1975-79. Since the 1980s an acceleration in the increase of M+kSD(M+), our indicator of the longest life durations, has been essentially due to the pause in SD(M+). Our data do not suggest that we are approaching an upper limit in human longevity.     

Cognitive Disparities: The Impact of the Great Depression and Cumulative Inequality on Later-Life Cognitive Function

Population aging has driven a spate of recent research on later-life cognitive function. Greater longevity increases the lifetime risk of memory diseases that compromise the cognitive abilities vital to well-being. Alzheimer’s disease, thought to be the most common underlying pathology for elders’ cognitive dysfunction (Willis and Hakim 2013), is already the sixth leading cause of death in the United States (Alzheimer’s Association 2016). Understanding social determinants of pathological cognitive decline is key to crafting interventions, but evidence is inconclusive for how social factors interact over the life course to affect cognitive function. I study whether early-life exposure to the Great Depression is directly associated with later-life cognitive function, influences risky behaviors over the life course, and/or accumulates with other life-course disadvantages. Using growth curve models to analyze the Health and Retirement Study, I find that early-life exposure to the Great Depression is associated with fluid cognition, controlling for intervening factors—evidence for a critical period model. I find little support for a social trajectory model. Disadvantage accumulates over the life course to predict worse cognitive function, providing strong evidence for a cumulative inequality model.     

Brave New Worlds: Philosophy,Politics, and Science in Human Biotechnology

Advances in biotechnology have important applications to the core demographic concerns of human reproduction and longevity, raising a number of difficult ethical issues. In the debate over those issues, however, the voices of demographers and other social scientists are nearly silent. In the United States the dominant bioethical arguments currently heard come from a conservative political and ideological position, represented, for example, by the President's Council on Bioethics and in particular by its chairman, Leon Kass. A critical discussion of Kass's writings identifies the philosophical roots of that position and highlights its logic and limits. Kass's specific arguments on cloning can be challenged by applying them to an earlier and revolutionary technology, birth control; his views on death and dying would argue for curtailing investment in life‐extending technology. Conservatism of this kind ignores social science perspectives and forecloses opportunities for social change.     

Period‐Based Mortality Change: Turning Points in Trends since 1950

We investigate a major turning point in mortality trends at adult ages that occurred for many low‐mortality countries in the late 1960s or early 1970s. We analyze patterns of total and cause‐specific mortality over the past 60 years using data from the Human Mortality Database and the World Health Organization. We focus on four broad categories of causes of death: heart diseases, cerebrovascular diseases, smoking‐related cancers, and all other cancers. We use a two‐slope regression model to assess the timing and magnitude of turning points in mortality trends over this era, making separate analyses by sex, age, and cause of death. The age pattern of temporal changes is given particular attention. Our results demonstrate convincingly that period‐based factors were very significant in the onset of the “cardiovascular revolution” in the years around 1970. In general, although cohort processes cannot be ruled out as a driver of mortality change in recent decades (especially for mortality due to smoking‐related cancers), the evidence reviewed here suggests that period factors have been the dominant force behind the mortality trends of high‐income countries during this era.     

Beyond Material Explanations: Family Solidarity and Mortality,a Small Area‐level Analysis

Social solidarity, being embedded in a network of binding social relationships, tends to extend human longevity. Yet while average incomes in the Western world, and with them, life expectancies, have risen dramatically, the second demographic transition has occasioned a breakdown in traditional family forms. This article considers whether these trends in family life may have slowed the rise in life expectancy. I present a cross‐sectional analysis of Israeli statistical areas (SAs), for which I construct indexes of Standard of Living (SOL), Traditional Family Structure (TFS), and Religiosity (R). I show that (1) increases in all three of these indexes are associated with lower levels of mortality, (2) male mortality is more sensitive to differences in SOL and TFS than is female mortality, and (3) net of differences in SOL and TFS, there is no difference in the mortality levels of Arab and Jewish populations.     

Three measures of longevity: Time trends and record values

This article examines the trend over time in the measures of “typical” longevity experienced by members of a population: life expectancy at birth, and the median and modal ages at death. The article also analyzes trends in record values observed for all three measures. The record life expectancy at birth increased from a level of 44 years in Sweden in 1840 to 82 years in Japan in 2005. The record median age at death shows increasing patterns similar to those observed in life expectancy at birth. However, the record modal age at death changes very little until the second half of the twentieth century: it moved from a plateau level, around age 80, to having a similar pace of increase as that observed for the mean and the median in most recent years. These findings explain the previously observed uninterrupted increase in the record life expectancy. The cause of this increase has changed over time from a dominance of child mortality reductions to a dominance of adult mortality reductions, which became evident by studying trends in the record modal age at death.     

Increasing longevity and medicare expenditures

Official Medicare projections forecast that the elderly population will be less healthy and more costly over the next century. This prediction stems from the use of age as an indicator of health status: increases in longevity are assumed to increase demand for health care as individuals survive to older and higher-use ages. In this paper I suggest an alternative approach, in which time until death replaces age as the demographic indicator of health status. Increases in longevity are assumed to postpone the higher Medicare use and costs associated with the final decade of life. I contrast the two approaches, using mortality forecasts consistent with recent projections from the U.S. Census Bureau and the Social Security Administration. The time-until-death method yields significantly lower-cost forecasts. The hypothetical cost savings from improved health care small, however, relative to the size of the Medicare solvency problem caused by population aging.     

The Patterns of Disability in the Peripheral Neighborhoods of Ouagadougou,Burkina Faso,and the Male–Female Health‐Survival Paradox

Disability is a crucial health and social concern in sub‐Saharan Africa, where a high prevalence of disabling diseases is compounded with insufficient care provision. There is a need for detailed analysis of the disability patterns. We provide a gender‐specific picture for the population in peripheral Ouagadougou (Burkina‐Faso), based on six disability dimensions following the United Nations’ recommendations. We computed disability‐free life expectancy (LE) using the Health and Demographic Surveillance System (Ouaga HDSS) (n = 1 902). Women have a longer partial LE in the 20–79 age range (+3.3 years), half of this LE being spent with a disability, versus 31% of the LE for men. Limitations in mobility, cognition, and eyesight occur in midadulthood and result in a considerable disadvantage for women in the number of years with these limitations. These findings highlight disability patterns that are detrimental to social participation and claim for better screening and care, especially for women.     

The gender longevity gap: explaining the difference between singles and couples

This paper studies the respective gender longevity gap in favour of women among singles, utilitarian and altruistic couples. The following hypotheses are derived: (1) the gender longevity gap is smaller within couples than among singles; (2) marriage increases longevity of men but decreases longevity of women; and (3) the gender longevity gap decreases with an increase in wealth. The hypotheses are tested using a complete data set of the Swiss deceased at the age 65+ in 2001 and 2002, with information on the individuals’ age at death and their average earnings over the life cycle.     

Trends in senescent life expectancy

The distinction between senescent and non-senescent mortality proves to be very valuable for describing and analysing age patterns of death rates. Unfortunately, standard methods for estimating these mortality components are lacking. The first part of this paper discusses alternative methods for estimating background and senescent mortality among adults and proposes a simple approach based on death rates by causes of death. The second part examines trends in senescent life expectancy (i.e., the life expectancy implied by senescent mortality) and compares them with trends in conventional longevity indicators between 1960 and 2000 in a group of 17 developed countries with low mortality. Senescent life expectancy for females rises at an average rate of 1.54 years per decade between 1960 and 2000 in these countries. The shape of the distribution of senescent deaths by age remains relatively invariant while the entire distribution shifts over time to higher ages as longevity rises.     

Life Expectancy during the Great Depression in Eleven European Countries

The recent global economic recession has renewed interest in knowing whether a declining economy affects population health. Understanding the extreme case of the Great Depression may inform the current debate as well as theory regarding biological and behavioral adaptations to unwanted economic change. We test the hypothesis, recently suggested in the literature, that period life expectancy at birth improved during the Great Depression. We applied time‐series methods to annual period life expectancy data of the civilian population from eleven European countries. Methods control for trends and other forms of autocorrelation in life expectancy that could induce spurious associations. We cannot reject the null hypothesis that period life expectancy at birth during the Great Depression remained within the interval forecasted from historical values. Additional analyses using an automated, rule‐based methodology also cannot reject the null hypothesis. During the most severe phase of the Great Depression, period life expectancy in eleven European countries generally did not rise above expected levels.