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 decrease with age, because the higher initial death rates in disadvantaged populations are compensated by lower pace of mortality increase with age. The age at which this imaginary (extrapolated) convergence of mortality trajectories takes place is named the "species-specific life span" (see Gavrilov and Gavrilova, 1979). For human beings, this human species-specific life span is close to 95 years (Gavrilov and Gavrilova, 1979; 1991).

Compensation law of mortality is a paradoxical empirical observation, and it represents a challenge for methods of survival analysis

Survival analysis

Survival analysis is a branch of statistics which deals with death in biological organisms and failure in mechanical systems. This topic is called reliability theory or reliability analysis in engineering, and duration analysis or duration modeling in economics or sociology...

 based on proportionality assumption (proportional hazard models). The compensation law of mortality also represents a great challenge for many theories of aging and mortality

Death

Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

, which usually fail to explain this phenomenon. On the other hand, the compensation law follows directly from the reliability theory

Reliability theory

Reliability theory describes the probability of a system completing its expected function during an interval of time. It is the basis of reliability engineering, which is an area of study focused on optimizing the reliability, or probability of successful functioning, of systems, such as airplanes,...

, when the compared systems have different initial levels of redundancy

Redundancy (engineering)

In engineering, redundancy is the duplication of critical components or functions of a system with the intention of increasing reliability of the system, usually in the case of a backup or fail-safe....

.

See also

• Ageing
  Ageing
  Ageing or aging is the accumulation of changes in a person over time. Ageing in humans refers to a multidimensional process of physical, psychological, and social change. Some dimensions of ageing grow and expand over time, while others decline...
  
  
• Biodemography of human longevity
  Biodemography of human longevity
  Biodemography is a multidisciplinary approach, integrating biological knowledge with demographic research on human longevity and survival...
  
  
• Biogerontology
  Gerontology
  Gerontology is the study of the social, psychological and biological aspects of aging...
  
  
• Demography
  Demography
  Demography 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...
  
  
• Mortality
  Mortality rate
  Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...
  
  
• Reliability theory of aging and longevity
  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:...