Allelic variation and human longevity

Human longevity is a complex phenotype with a strong genetic contribution. The search for allelic variation that impacts on longevity often involves population-based association studies of long-lived individuals (centenarians and nonagenarians) and younger controls. A major methodological problem with this approach is that the cases and controls in these experiments are often born several generations apart. The inherent absence of "age matching" can lead to serious misinterpretations. For example, allele frequency differences between long-lived individuals and younger controls may not reflect an effect on longevity but rather a change in population structure over time or different gene-environment interactions across generations.     

The unusual genetics of human longevity

In no species other than humans do cultural, social, and biological factors interact with each other in modulating complex phenotypes. Thus, the identification of genetic factors that affect human longevity is a true challenge. The model of centenarians provides us a unique opportunity to tackle this challenge. In this Perspective, we discuss some recent findings (the impact of geography and demography on the longevity phenotype, the relationship between longevity and homozygosity, the role of the nuclear-mitochondrial genome cross-talk) by which new ideas are suggested, such as the concept of a complex allele timing as a pivotal process in modulating the probability of achieving longevity.     

Change resistance moderates existence and longevity biases

Evidence has been found for existence and longevity biases—inferences of goodness from prevalence or longevity. We argue these biases actually emerge among change-resisting individuals. Our evidence suggests change-accepting individuals can even demonstrate a reversal of these biases. In two studies, change-resisting individuals’ attitudes were suggestive of existence and longevity biases while change-accepting individuals significantly reversed this pattern by evaluating long-standing or prevalent objects less favorably. Finally, we reanalyzed data from the existence and longevity biases literature previously reported in Social Influence. We found Americans identifying as more Republican—thus theorized as more change-resisting—were those who favored a long-standing practice. Altogether, we argue that existence and longevity biases emerge depending on individuals’ change resistance, indicating an important theoretical expansion.     

Maintaining your immune system--one method for enhanced longevity

The immune system is an important evolutionary invention to battle invaders in young and old organisms. Successful aging in humans who achieve nonagenarian status and beyond depends on how the immune system changes over time. Whether certain immune parameters vary with increased age is influenced by the genotype and lifestyle of the individual.     

Social movement coalitions: Formation,longevity, and success

Social movements rely on coalitions to help mobilize the mass numbers of people necessary for success. In this article, we review the literature on social movement coalition formation, longevity, and success. We identify five factors critical to coalition formation: (a) social ties; (b) conducive organizational structures; (c) ideology, culture, and identity; (d) the institutional environment; and (e) resources. Next, we explore the extent to which coalition survival is influenced by these same factors and argue that emergent properties of the coalition, such as commitment and trust, also facilitate longevity. Our review of the literature reveals that two factors specific to coalitions influence their success: coalition form and the nature of institutional targets. Interaction, communication technology, and the availability of physical and virtual spaces that facilitate communication are themes that run throughout our discussion, as they undergird many of the elements that shape coalition formation and survival. We conclude by evaluating the state of the research area and suggesting directions for further research.     

The quest for a general theory of aging and longevity

Extensive studies of phenomena related to aging have produced many diverse findings, which require a general theoretical framework to be organized into a comprehensive body of knowledge. As demonstrated by the success of evolutionary theories of aging, quite general theoretical considerations can be very useful when applied to research on aging. In this theoretical study, we attempt to gain insight into aging by applying a general theory of systems failure known as reliability theory. Considerations of this theory lead to the following conclusions: (i) Redundancy is a concept of crucial importance for understanding aging, particularly the systemic nature of aging. Systems that are redundant in numbers of irreplaceable elements deteriorate (that is, age) over time, even if they are built of elements that do not themselves age. (ii) An apparent aging rate or expression of aging is higher for systems that have higher levels of redundancy. (iii) Redundancy exhaustion over the life course explains a number of observations about mortality, including mortality convergence at later life (when death rates are becoming relatively similar at advanced ages for different populations of the same species) as well as late-life mortality deceleration, leveling off, and mortality plateaus. (iv) Living organisms apparently contain a high load of initial damage from the early stages of development, and therefore their life span and aging patterns may be sensitive to early-life conditions that determine this initial damage load. Thus, the reliability theory provides a parsimonious explanation for many important aging-related phenomena and suggests a number of interesting testable predictions. We therefore suggest adding the reliability theory to the arsenal of methodological approaches applied to research on aging.     

The effect of longevity on spending for acute and long-term care

Reproduced with permission     

Why females live longer than males: control of longevity by sex hormones

Females live longer than males in many species, including humans. We have traced a possible explanation for this phenomenon to the beneficial action of estrogens, which bind to estrogen receptors and increase the expression of longevity-associated genes, including those encoding the antioxidant enzymes superoxide dismutase and glutathione peroxidase. As a result, mitochondria from females produce fewer reactive oxygen species than those from males. Administering estrogens has serious drawbacks, however--they are feminizing (and thus cannot be administered to males) and may increase the incidence of serious diseases such as uterine cancer in postmenopausal women. Phytoestrogens, which are present in soy or wine, may have some of the favorable effects of estrogens without their undesirable effects. Study of gender differences in longevity may help us to understand the basic processes of aging and to devise practical strategies to increase the longevity of both females and males.     

Revising the standard wisdom of C. elegans natural history: ecology of longevity

Here, we consider that most of the research concerning Caenorhabditis elegans has been laboratory focused and that only limited research has directly considered the worm's biology relative to its natural history in the wild. We describe that, although the worm has traditionally been considered a soil nematode, we could not find it in soil but frequently recovered it from snails. Finally, we discuss how a better understanding of the natural history of C. elegans may enhance its usefulness as a model organism for studying aging and other phenomena.     

Genes, longevity, and technology: meeting report from the 2nd conference on functional genomics of aging in Crete

Whole-genome sequences are now available, and methods have evolved for targeting, in parallel, each gene in a genome, offering for the first time the opportunity to study the entire dynamic network of genes involved in aging. At a recent conference in Hersonissos, Crete, around 200 internationally renowned experts gathered to discuss techniques and emerging results as the science of aging undergoes a shift toward systems biology.