Biodemography of human longevity
Encyclopedia
Biodemography is a multidisciplinary approach, integrating biological knowledge (studies on human biology and animal models) with demographic research on human longevity and survival. Biodemographic studies are important for understanding the driving forces of the current longevity revolution (dramatic increase in human life expectancy), forecasting the future of human longevity, and identification of new strategies for further increase in healthy and productive life span.
Biodemographic studies found a remarkable similarity in survival dynamics between humans and laboratory animals. Specifically, three general biodemographic laws of survival are found:
The Gompertz-Makeham law
states that death rate is a sum of age-independent component (Makeham term) and age-dependent component (Gompertz function), which increases exponentially with age.
The Compensation law of mortality
(late-life mortality convergence) states that the relative differences in death rates between different populations of the same biological species are decreasing with age, because the higher initial death rates are compensated by lower pace of their increase with age.
The Late-life mortality deceleration law states that death rates stop to increase exponentially at advanced ages and level-off to the late-life mortality plateau. An immediate consequence from this observation is that there is no fixed upper limit to human longevity - there is no special fixed number, which separates possible and impossible values of lifespan. This challenges the common belief in existence of a fixed maximal human life span.
Biodemographic studies found that even genetically identical laboratory animals kept in constant environment have very different lengths of life, suggesting a crucial role of chance and early-life developmental noise in longevity determination. This leads to new approaches in understanding causes of exceptional human longevity.
As for the future of human longevity, biodemographic studies found that evolution of human lifespan had two very distinct stages – the initial stage of mortality decline at younger ages is now replaced by a new trend of preferential improvement of the oldest-old survival. This phenomenon invalidates methods of longevity forecasting based on extrapolation of long-term historical trends.
A general explanation of these biodemograhic laws of aging and longevity has been suggested based on system reliability theory
.
Biodemographic studies found a remarkable similarity in survival dynamics between humans and laboratory animals. Specifically, three general biodemographic laws of survival are found:
- Gompertz-Makeham law of mortalityGompertz-Makeham law of mortalityThe Gompertz–Makeham lawstates that the death rate is the sum of an age-independent component and an age-dependent component , which increases exponentially with age...
- Compensation law of mortalityCompensation law of mortalityThe compensation law of mortality states that the relative differences in death rates between different populations of the same biological species decrease with age, because the higher initial death rates in disadvantaged populations are compensated by lower pace of mortality increase with age...
- Late-life mortality deceleration.
The Gompertz-Makeham law
Gompertz-Makeham law of mortality
The Gompertz–Makeham lawstates that the death rate is the sum of an age-independent component and an age-dependent component , which increases exponentially with age...
states that death rate is a sum of age-independent component (Makeham term) and age-dependent component (Gompertz function), which increases exponentially with age.
The Compensation law of mortality
Compensation law of mortality
The compensation law of mortality states that the relative differences in death rates between different populations of the same biological species decrease with age, because the higher initial death rates in disadvantaged populations are compensated by lower pace of mortality increase with age...
(late-life mortality convergence) states that the relative differences in death rates between different populations of the same biological species are decreasing with age, because the higher initial death rates are compensated by lower pace of their increase with age.
The Late-life mortality deceleration law states that death rates stop to increase exponentially at advanced ages and level-off to the late-life mortality plateau. An immediate consequence from this observation is that there is no fixed upper limit to human longevity - there is no special fixed number, which separates possible and impossible values of lifespan. This challenges the common belief in existence of a fixed maximal human life span.
Biodemographic studies found that even genetically identical laboratory animals kept in constant environment have very different lengths of life, suggesting a crucial role of chance and early-life developmental noise in longevity determination. This leads to new approaches in understanding causes of exceptional human longevity.
As for the future of human longevity, biodemographic studies found that evolution of human lifespan had two very distinct stages – the initial stage of mortality decline at younger ages is now replaced by a new trend of preferential improvement of the oldest-old survival. This phenomenon invalidates methods of longevity forecasting based on extrapolation of long-term historical trends.
A general explanation of these biodemograhic laws of aging and longevity has been suggested based on system reliability theory
Reliability theory of aging and longevity
Reliability theory of aging and longevity is a scientific approach aimed to gain theoretical insights into mechanisms of biological aging and species survival patterns by applying a general theory of systems failure, known as reliability theory.-Overview:...
.
Further reading
- Leonid A. Gavrilov & Natalia S. Gavrilova (1991), The Biology of Life Span: A Quantitative Approach. New York: Harwood Academic Publisher, ISBN 3-7186-4983-7
- Gavrilov L.A., Gavrilova N.S., Olshansky S.J., Carnes B.A. 2002. Genealogical data and biodemography of human longevity. Social Biology, 49(3-4): 160-173.
- Gavrilov, L.A., Gavrilova, N.S. 2001. Biodemographic study of familial determinants of human longevity. Population: An English Selection, 13(1): 197-222.
See also
- DemographyDemographyDemography is the statistical study of human population. It can be a very general science that can be applied to any kind of dynamic human population, that is, one that changes over time or space...
- BiodemographyBiodemographyBiodemography is the science dealing with the integration of biology and demography.Biodemography is a new branch of human demography concerned with understanding the complementary biological and demographic determinants of and interactions between the birth and death processes that shape...
- LongevityLongevityThe word "longevity" is sometimes used as a synonym for "life expectancy" in demography or known as "long life", especially when it concerns someone or something lasting longer than expected ....
- Life extensionLife extensionLife extension science, also known as anti-aging medicine, experimental gerontology, and biomedical gerontology, is the study of slowing down or reversing the processes of aging to extend both the maximum and average lifespan...
- List of life extension-related topics
- Reliability theory of aging and longevityReliability theory of aging and longevityReliability theory of aging and longevity is a scientific approach aimed to gain theoretical insights into mechanisms of biological aging and species survival patterns by applying a general theory of systems failure, known as reliability theory.-Overview:...
External links
- Biodemography of Human Longevity - Abstract of keynote lecture, p. 42. In: Inaugural International Conference on Longevity. Final Programme and Abstracts. Sydney Convention & Exhibition Centre. Sydney, Australia, March 5–7, 2004, 94 pp