The history of mortality studies at extreme ages is very rich in ideas and findings.
Early studies starting with Gompertz (1825) himself suggested that the Gompertz law of
mortality is not applicable to extreme old ages, and that mortality deceleration and
leveling-off takes place at advanced ages (for an excellent historical review of studies on
mortality deceleration at extreme old ages, see Olshansky, 1998). In 1939 two British
researchers, Greenwood and Irwin, published an article “Biostatistics of Senility,” with
an intriguing finding that mortality force stops increasing with age at extreme old ages
and becomes constant (Greenwood and Irwin, 1939). Their study and findings were
considered to be so important that they were featured at the front page of academic
journal “Human Biology,” where their study was published. This study, accomplished by
the famous British statistician and epidemiologist, Major Greenwood, may be interesting
to discuss here because it correctly describes the mortality pattern at advanced ages for
humans.
surviving to extreme ages with subsequent efforts of strict age validation. This approach
helps researchers to resolve the third of the above-mentioned problems but does not
resolve the first two problems because of inevitable data heterogeneity when data for
people belonging to different birth cohorts and countries are pooled together.
surviving to extreme ages with subsequent efforts of strict age validation. This approach
helps researchers to resolve the third of the above-mentioned problems but does not
resolve the first two problems because of inevitable data heterogeneity when data for
people belonging to different birth cohorts and countries are pooled together.