Intergenerational changes in selected cranial measurements of adolescents from Poland from 1938 to 2020

Changes in the environment in which a particular population develops, including socio-economic factors, can influence craniofacial dimensions over time. The study aimed to investigate intergenerational changes in selected cranial measurements of adolescents (16-18 years of age) from Kraków, Poland. The analysis was based on the anthropometric measurements of four cohorts (years 1938, 1950, 2007 and 2020) of adolescents aged 16-18. Analysed characteristics included head breadth, length and head breadth-to-length ratio. The normality of each characteristic's distribution was assessed using Shapiro-Wilk's test, and the statistical significance of the differences between the cohorts was calculated using the two-way ANOVA or Kruskal-Wallis test. The pace of the secular changes of the analysed characteristics was also calculated. There was a secular increase in the head length from 1938 to 2020. The breadth of the head decreased between 1938 and 2007, but an increase was noted from 2007 to 2020. Changes analogous to head breadth were noted for the breadth-to-length ratio. The secular changes occurred the fastest between 2007 and 2020 for the length (18-year-olds), breadth (16-year old boys and 18-year-old girls) and the cephalic index (16-year old boys and 17-year-old girls). In conclusion, there was a tendency toward debrachycephalisation in the more contemporary cohorts. Observed changes may be associated with more favourable overall developmental conditions as well as possible changes in the growth tempo of the Polish population.