Old-age survival has considerably improved in the second half of the twentieth century. Why has such a substantial extension of human lifespan occurred? How long can we live? In this book, these fundamental questions are explored by experts from diverse fields. They report on recent cutting-edge studies about essential issues of human longevity and social factors of long survival in old age.
Two thousand years ago, the average life expectancy from birth to death of a Roman citizen, an individual better off than most people at that time, was about 22 years (wars, infectious diseases, trauma, etc.). This progressively increased to about 47 years in the U.S. and most European countries by 1900. Today, the average life expectancy in the U.S. is 78 years (women about five years more than men). However, unless the obesity pandemic is reversed and lifestyles improved, the average life expectancy will likely decrease significantly. conversely, if our lifestyles improve, the average life expectancy could reach 85 or more years. Growing older does not necessarily mean growing sicker. Thus, "don't just add years to your life, add life to your years" (Hans Selve). Indeed, of the 15 major causes of death in the U.S., 65-70% are lifestyle-related. In this book, the following documented topics that are associated with diseases and mortality are discussed in detail: theories of aging; diseases and mortality associated with obesity, physical inactivity and poor nutrition; psychological stress (anxiety, depression); addiction (alcohol, tobacco, drugs); violence (suicide, homicide); food-borne and infectious diseases (viral, bacterial, parasitic); and various other conditions (air pollution, asbestosis, trace metals).
Why longevity? For a number of years, the Fondation IPSEN has been devoting considerable effort to the various aspects of ageing, not only to age-related diseases such as Alzheimer's, but also to the Centenarians, the paragon of positive ageing. The logical continuation of this approach is to address the question of longevity in global terms. Behind the extreme values, what span is accessible to all of us and likely to directly concern most of our contemporaries? The individual and col lective increase in the duration of life is one of the most striking phenomena of our time. It could be one of the most significant events in the "bio-social" history of humanity. The increase in life expectancy at old age, which started a few de cades ago only, is going on. The most well-advised observer had not foreseen or even dared hope for this increase which will drastically affect our everyday life, our habits and our behavior. In the fragment of human history we are living in, it is our responsibility to deal with this major transformation for the species. Such a transformation needs an effort from all to adapt to the new conditions. This transformation has to be managed rather than simply experienced, anticip ated rather than followed, in order to avoid any attempt to pervert this major step forward. All that was present during the first symposium of the new series on longevity of the Colloques Medecine et Recherche convened by the Fondation IPSEN.
The proportion of elderly people continues to increase in the western world-nearly a quarter of the population will be over 65 years by the year 2050. Since aging is accompanied by an increase in diseases and by a deterioration in well-being, finding solutions to these social, medical and psychological problems is necessarily a major goal for society. Scientists and medical practitioners are therefore faced with the urgent task of increasing basic knowledge of the biological processes that cause aging. More resources must be put into this research in order to achieve better understanding of the cellular mechanisms that underlie the differences in life span between species and to answer the difficult questions of why some individuals age more quickly than others, and why some develop liver problems, some have heart problems, and others brain problems. The results of such a wide program of research will provide important information about the causes of many life-threatening and/ or debilitating diseases of old age; it will help find ways to prevent some of the ailments that result from aging, and it may well lead to discoveries enabling the prolongation of human life.
States that the number of genuine long-livers is exploding and a substantial proportion of new-borns in developed countries may survive to celebrate their 100th birthday. This book examines the storied realms of exceptional longevity.
Despite our deep interest in mortality, little is known about why some individuals live to middle age and others to extreme old age. Life span, mortality, and aging present some of the most profound mysteries in biology. In Longevity, James Carey draws on unprecedented data to develop a biological and demographic framework for identifying the key factors that govern aging, life span, and mortality in humans and other animals. Carey presents the results of a monumental, twelve-year, National Institute on Aging-funded research project on the determinants of longevity using data from the life tables of five million Mediterranean fruit flies, the most comprehensive set of life table studies ever on the mortality dynamics of a single species. He interprets the fruit fly data within the context of human aging and the aging process in general to identify the determinants of mortality. Three key themes emerge: the absence of species-specific life span limits, the context-specific nature of the mortality rate, and biodemographic linkages between longevity and reproduction. A powerful foundation for the emerging field of biodemography and a rich framework for considering the future of human life span, Longevity will be an indispensable resource for readers from a range of fields including population biology, demography, gerontology, ecology, evolutionary biology, and medical research.
The proportion of elderly people continues to increase in the western world-nearly a quarter of the population will be over 65 years by the year 2050. Since aging is accompanied by an increase in diseases and by a deterioration in well-being, finding solutions to these social, medical and psychological problems is necessarily a major goal for society. Scientists and medical practitioners are therefore faced with the urgent task of increasing basic knowledge of the biological processes that cause aging. More resources must be put into this research in order to achieve better understanding of the cellular mechanisms that underlie the differences in life span between species and to answer the difficult questions of why some individuals age more quickly than others, and why some develop liver problems, some have heart problems, and others brain problems. The results of such a wide program of research will provide important information about the causes of many life-threatening and/ or debilitating diseases of old age; it will help find ways to prevent some of the ailments that result from aging, and it may well lead to discoveries enabling the prolongation of human life.
During the last 25 years, life expectancy at age 50 in the United States has been rising, but at a slower pace than in many other high-income countries, such as Japan and Australia. This difference is particularly notable given that the United States spends more on health care than any other nation. Concerned about this divergence, the National Institute on Aging asked the National Research Council to examine evidence on its possible causes. According to Explaining Divergent Levels of Longevity in High-Income Countries, the nation's history of heavy smoking is a major reason why lifespans in the United States fall short of those in many other high-income nations. Evidence suggests that current obesity levels play a substantial part as well. The book reports that lack of universal access to health care in the U.S. also has increased mortality and reduced life expectancy, though this is a less significant factor for those over age 65 because of Medicare access. For the main causes of death at older ages-cancer and cardiovascular disease-available indicators do not suggest that the U.S. health care system is failing to prevent deaths that would be averted elsewhere. In fact, cancer detection and survival appear to be better in the U.S. than in most other high-income nations, and survival rates following a heart attack also are favorable. Explaining Divergent Levels of Longevity in High-Income Countries identifies many gaps in research. For instance, while lung cancer deaths are a reliable marker of the damage from smoking, no clear-cut marker exists for obesity, physical inactivity, social integration, or other risks considered in this book. Moreover, evaluation of these risk factors is based on observational studies, which-unlike randomized controlled trials-are subject to many biases.
Demographers and public health specialists have been surprised by the rapid increases in life expectancy, especially at the oldest ages, that have occurred since the early 1960s. Some scientists are calling into question the idea of a fixed upper limit for the human life span. There is new evidence about the genetic bases for both humans and other species. There are also new theories and models of the role of mutations accumulating over the life span and the possible evolutionary advantages of survival after the reproductive years. This volume deals with such diverse topics as the role of the elderly in other species and among human societies past and present, the contribution of evolutionary theory to our understanding of human longevity and intergenerational transfers, mathematical models for survival, and the potential for collecting genetic material in household surveys. It will be particularly valuable for promoting communication between the social and life sciences.
