"The purpose of this paper is to examine the long-term trends of life tables in developed countries according to two parameters of the Brass system in order to find the range of variation, consistent with historical life tables (or, in other words, to define 'a field of epidemiological transition')."  The author finds that "1) In the past, the mortality curves had U- and J-shapes, the latter being connected with the impact of demographic crises....2) The elimination of the crisis component at the first stage of the transition resulted in the transformation of the mortality curves towards the U-shape....3) At the second stage social control is established over premature mortality. As a result, life expectancy grows, and the shape of the curves moves towards the J-shape....4) In the past the male and female life tables usually did not differ from each other as regards the value of the Brass model parameters.  However, in the last 30-40 years considerable sexual differences emerged both in the level and in the shape of the mortality curves." (SUMMARY IN FRE)