Background: Poland is considered an ethnically homogeneous country, with no significant national, linguistic, religious or racial minorities. Thus, social differences in rates of maturation, height and weight may be assumed to contain a negligible genetic component and serve as a reflection of environment, i.e. living conditions.
Aim: This study seeks to determine whether changes in economic conditions in Poland, in particular the acute economic crisis of 1977-1989 and the transformation of the political system in 1989, had an effect on the biological status of girls from various categories of the rural population.
Subjects and methods: Rural girls aged 9.5-18.5 years were studied in 1967 (n = 7889), 1977 (n = 7771), 1987 (n = 13 556) and in 2001 (n = 9599). The stratification of participants (farmers, farm-workers and non-farmers) was based on the source of their family income, parents' education, number of children per family and household appliances. Age at menarche (AM), body height, and weight were used as biological indicators of living conditions.
Results: During the decade 1967-1977, while a relatively good economic situation prevailed in the country, AM decreased by 0.64 years and distinct secular trends in height and weight were noted. During the decade 1977-1987, years of economic crisis, secular trends were arrested and AM increased by 0.11 years. Landless rural families were more strongly affected by food shortages than were farmers who were the food producers. The study, repeated in 2001, showed positive secular trends in body height and a decrease in AM of 0.24 years for decade for daughters of farmers this decrease in AM was twice as high as in non-farmer families. The latter group experienced acute unemployment after the political and economic system transformation (1989). AM was earliest in daughters of non-farmers, and latest in those from farmer families. In 1967, the difference between the mean ages at AM for these groups amounted to 0.53 years, in 1977 to 0.44 years, in 1987 to 0.33 years and to only 0.15 years in 2001.
Conclusion: The categories of the rural population, farmers, farm-workers and landless rural inhabitants were variously affected by the economic crisis, as well as by the process of economic transformation. This shows that living conditions of each of those categories changed in different ways and to a different degree during the years 1967-2001. Farmers' families achieved the highest social advancement, as the AM of girls from those families decreased by 0.98 years compared to those from farmer-worker and landless rural families, which decreased by 0.85 and 0.60 years, respectively.