From Big Medical Encyclopedia

LIFE EXPECTANCY — duration of existence of an individual of each view from the moment of the birth and to death, caused genetically and depending on many factors. Distinguish physiological and ecological the Item. Physiological is understood maximum as the Item. with preservation of optimal conditions of existence, depending hl. obr. from genetic features of a look; under ecological — the age limit of individuals under natural conditions caused by many environmental factors. These concepts are almost difficult differentiated, usually tell about maximum the specific Item. irrespective of, observe it in simulated or natural conditions. There are also concepts defining potentialitys of the Item. — biological Item., vital limit etc.

Item. some plants it is estimated in the millennia (baobabs, sequoias), at animals — decades (whales live 30 — 50 years, elephants — 60 — 80 years, separate species of turtles — St. 150 years). Since the time of Aristotle attempts to find dependence of the Item become. from a growth period, the relative size of a brain (cephalization), etc. the Item. the person the hl is defined not only by his biological, hereditary features, but also. obr. social living conditions (life, work, rest, food). I. I. Mechnikov, e.g., considered that the person shall live twice longer, than he lives, up to 150 years. Data on the people who lived 150 years and more (Makhmut Ayvazov — 168 years), in special literature are called in question; it is considered that these figures do not maintain strict scientific check, and the valid age of long-livers, e.g. according to Comfort (A. Comfort, 1967), does not exceed 110 — 120 years. The existing records of the Item. at the person reflect its specific biol. opportunities, however most of scientists determines more limited terms it natural the specific Item. — 110 — 115 years.

Studying of the Item. and potentialitys of the person it is closely connected with studying of process of aging (see. Old age, aging ) and reasons death (see). Distinguish pathological (premature) and normal aging. Natural death, i.e. death as a result of normal aging, practically in statistics is not registered since according to the existing rules in the medical certificate on death as the reason either the disease, or an injury surely is specified. The diagnosis «senile decrepitude» is considered defective.

A demographic indicator — the average duration of the forthcoming life — characterizes the Item. not a separate individual, but population in general. It is based on probability theory (see. Probabilities theory ) also it is estimated according to tables of mortality (tables of survival, life expectancy, extinction), according to tables of life etc. It is wrong to determine average by the Item. as average age of the dead or as average age of living.

Tables of mortality are formed on the basis of age and sex mortality rates and show how it is consecutive, from the birth up to 100 years year after year, the number of generation decreases. For drawing up tables of mortality by a demographic method the data on population on separate age received by hl are initial. obr. during the population censuses, and about the number of the dead at the same age. These tables characterize the Item. not real, but hypothetical generation and actually estimate age and sex rates of mortality for a year of drawing up tables.

Attempts to track one generation for 100 years (a direct method of drawing up tables of mortality) practically were unreal and the received results would not have the practical value since they would be constructed on rates of mortality of various periods, various socially incomparable conditions (see. Mortality ).

As for calculation of age and sex rates of mortality data on number of the dead and living in each age group are necessary, tables of mortality usually can be expected years of population censuses (see. Population census ). Drawing up tables in intercensus years on the basis of the current estimates of vozrastnopolovy structure of the population is accompanied by additional calculations.

According to the first tables of mortality made by the Roman lawyer Domitius Ulpianus (2 and 3 centuries), average the Item. made 22,4 years; on E. Rosset during an era of bronze and iron average the Item. — 20 years, in the Middle Ages — 25 — 30 years, in 19 century — 30 — 50 years. In 20 century there was its significant increase up to 40 — 75 years in connection with development of economy, culture and achievements in the field of health care.

In imperial Russia average the Item. in 1896 — 1897 was 32 years (the years adjoining a population census. when the first authentic tables of mortality were made). In the USSR in 1926 — 1927 average the Item. there were 44 years, in 1958 — 1959 — 69 years and in 1970 — 1971 — 70 years. Dynamics of average duration of the forthcoming life in the USSR for various age groups of the population, on materials of the conducted population censuses, is presented in tab. 1.

Table 1. DYNAMICS of AVERAGE DURATION of the FORTHCOMING LIFE In the USSR FOR PERSONS of DIFFERENT AGE according to POPULATION CENSUSES 1896 — 1897, 1926 — 1927, 1958 — 1959 1970 — 1971 (advanced in years)

Increase in average in the Item. to the USSR went hl. obr. due to decline in mortality in children's (see. Child mortality ) and young working-age; in elderly and senile groups it was less considerable. It also means that further increase in average in the Item. will occur more slowly since its main reserve — decrease in child mortality and mortality at young working-age — was reduced.

Average Item. around the world in 1970 it was estimated in 55 years, in 1975 — 60 years. In 1975 average the Item. the lowest was in Africa — 47 years. The greatest average Item. in 1976 — 1978 was in the Netherlands, Norway, Sweden and Japan (tab. 2).

Table 2. The AVERAGE DURATION of the FORTHCOMING LIFE ACCORDING TO WHO DATA and SEV for 1971 — 1978 (advanced in years)

According to the UN, average Item. in economically underdeveloped countries in comparison with developed nearly 20 years less (tab. 3).

Explicit dependence of average of the Item is found. from a social status in society. In 1959 — 1961 in the USA average the Item. at the white population was 67,6 years at men and women have 74,2 years, at not white population — 61,5 and 66,5 years respectively.


In the majority of the countries rates of increase in average of the Item. at men is lower, than at women that leads to growth of a difference of average of the Item. at men and women; in a number of the countries this gap fluctuates from 4,5 to 10 years. In the 70th these distinctions became more noticeable, than in former years. In Bulgaria, e.g., a difference of average of the Item. men and women in 1969 — 1971 made 5,3 years (1,58 years in 1935 — 1939, 0,63 years in 1921 — 1925 and 0,12 years in 1900 — 1905). The reasons of higher mortality of men leading to the smaller duration of their life both biological, and social. It is considered that biological the Item. women are 2,1 years more, than at men. The social reasons multilaterally — effects of wars, accidents, alcoholism, smoking, etc.

At a hypothetical assumption of elimination of mortality from separate diseases it is possible to define how it will influence increase in the Item.

And. M. Merkov and M. S. Bedny calculated that, e.g., at elimination of mortality from malignant new growths of the Item. men would increase on 3,53, and women — for 3,03; from diseases of a respiratory organs increase will make respectively 1,82 and 0,92 years; from injuries and accidents — 3,50 and 1,16 years; vascular damages of the central nervous system — 1,64 and 2,04 years; atherosclerosis of coronary vessels and a myocardial infarction — 0,38 and 0,52; an idiopathic hypertensia — 1,35 and 1,42; other heart troubles — 1,35 and 1,42 years.

Except average the Item., tables of mortality allow to define also other indicators characterizing life expectancy, napr, modal by the Item., probable, or median, Item. etc.

Modal Item. call age of which the greatest number of the dead, apart from the dead on the first year of life are the share. In the USSR in 1958 — 1959 men of 77 — 78 years had a modal life expectancy, women have 81 years, in 1926 — 1927 — 72 and 74 respectively.

Probable, or median, Item. — the size of that interval of age, later to-rogo number of living decreases twice, i.e. makes 50% of initial set; it is called probable because probability to live up to the age corresponding median to the Item., it is equal to probability to endure this term.

A number of attempts to statistically prove limits biological by the Item was accepted.; e.g., Bourgeois-Piche in 1952 made optimum, or biological, tables of mortality, having excluded some so-called exogenous causes of death — diseases and injuries concerning which the science and practice have real opportunities of their elimination. According to these tables average the Item. men — 76,3 years, women — 78,2, both floors — 77,3 years. B. Ts. Urlanis suggests to consider biological such the Item., will pass edges in favorable social conditions and will break after exhaustion of genetic potential. By its calculations biological life expectancy in the USSR, by data in 1958 — 1959, men — 86,0, women — 88,1 years.

Item. the person — category social and biological, and forecasts concerning its size in far or relatively the near future are connected with changes of the social environment. It is obvious that perhaps achievable limits of lengthening of human life — the size changing, time-dependent and diverse conditions and factors, and its forecasting shall be based on modern methods, proceeding from exact, objective and strictly scientific data.

See also Demographic statistics , Longevity .

Bibliography: Poor M. S. Life expectancy, M., 1967, bibliogr.; it, medico-demographic studying of the population, M., 1979; Studying of life expectancy, under the editorship of E. M. Andreyev and A. G. Volkov, page 151, M., 1977; A. Biologiya's Comfort of aging, the lane with English, M., 1967; Dews sets E. Duration of human life, the lane with polsk., M., 1981, bibliogr.; Urlanis B. Ts. Evolution of life expectancy, M., 1978.

V. A. Nesterov.