acceleration (human development) acceleration (human development) acceleration in human development process is the phenomenon which has been registered in many populations around the world. this applies equally to the growth of certain anthropometric parameters and the speed of reaching sexual maturity. these facts illustrate the results of secular changes in body height and appearance of the first menstruation (menarche). secular trend in decrease in age of menarche in western european and north american girlsafter: stature comparison between american-born children of european descent and earlier populations of the same heritageafter: increases in human stature are a main indicator of improvements in the average health of populations. the newest data set for the average height of adult male birth cohorts, from the mid-nineteenth century to 1980, in 15 european countries was studied (in the populations listed). during a century average height increased by 11 cm representing a dramatic improvement of this phenomenon. the apparent acceleration of body height occurred during the periods around the two world wars and after the great depression. in the mid-nineteenth century european girls' menarche occurred at the average age of 16.5 years. one hundred years later, this age was reduced to under 12 years. increase in adult height of birth cohorts (cm/decade) population 1871–1875to 1976–1980 1871–1875to 1911–1915 1911–1915to 1951–1955 1951–1955to 1976–1980 austria 1.11 0.59 1.50 1.32 belgium 1.08 0.41 1.59 1.32 bosnia and herzegovina 2.00 denmark 1.24 0.58 1.83 1.37 finland 0.84 france 0.91 0.57 1.10 1.16 germany 1.25 1.20 great britain 0.93 1.14 0.99 0.50 greece 1.55 ireland 0.80 1.00 italy 1.06 0.72 1.14 1.50 netherlands 1.41 1.34 1.32 1.67 norway 0.93 0.79 1.49 0.26 portugal 0.94 1.72 spain 1.19 0.74 0.79 2.53 sweden 0.97 0.68 1.25 1.00 average 1.08 0.76 1.27 1.26 standard deviation 0.18 0.28 0.31 0.54