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.

Theory

Biodemographic studies have 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 mortality The Gompertz–Makeham law states that the human death rate is the sum of an age-dependent component (the Gompertz function, named after Benjamin Gompertz), which increases exponentially with age and an age-independent component (the Makeham ter ...

Compensation law of mortality The compensation law of mortality (or late-life mortality convergence) 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 disa ...

Late-life mortality deceleration In gerontology, late-life mortality deceleration is the disputed theory that hazard rate increases at a decreasing rate in late life rather than increasing exponentially as in the Gompertz law. Late-life mortality deceleration is a well-establi ...

(now disputed *) The Gompertz–Makeham law states that death rate is a sum of age-independent component ( Makeham term) and age-dependent component (

Gompertz function The Gompertz curve or Gompertz function is a type of mathematical model for a time series, named after Benjamin Gompertz (1779–1865). It is a sigmoid function which describes growth as being slowest at the start and end of a given time period. Th ...

), which increases exponentially with age. The

compensation law of mortality The compensation law of mortality (or late-life mortality convergence) 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 disa ...

(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 disputed

late-life mortality deceleration In gerontology, late-life mortality deceleration is the disputed theory that hazard rate increases at a decreasing rate in late life rather than increasing exponentially as in the Gompertz law. Late-life mortality deceleration is a well-establi ...

law states that death rates stop increasing exponentially at advanced ages and level off to the

late-life mortality plateau In gerontology, late-life mortality deceleration is the disputed theory that hazard rate increases at a decreasing rate in late life rather than increasing exponentially as in the Gompertz law. Late-life mortality deceleration is a well-establ ...

. A consequence of this deceleration is that there would be no fixed upper limit to human longevity — no fixed number which separates possible and impossible values of lifespan. If true, this would challenges the common beliefGavrilov L.A. Does a limit of the life span really exist? Biophysics iofizika 1984, 29(5): 908–911. in existence of a fixed maximal human life span. Biodemographic studies have 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 biodemographic laws of aging and longevity has been suggested based on system

reliability theory Reliability engineering is a sub-discipline of systems engineering that emphasizes the ability of equipment to function without failure. Reliability describes the ability of a system or component to function under stated conditions for a specifi ...

References

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 {{DEFAULTSORT:Biodemography Of Human Longevity Ageing Gerontology Medical aspects of death Population

Theory

See also

References

Further reading

External links