Acceleration (biology)

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In biology, acceleration is an acceleration of development. It was described for the first time by the school doctor EW Koch, who called it "secular acceleration". Today the term: "Psychophysical acceleration" is also in use ("secular trend"). The beginning of the first half of the 19th century is assumed. Meanwhile, the changes seem to have stalled.

Growth acceleration

In the industrialized nations, the height of people is increasing from generation to generation. So was z. For example, a tall man (95th percentile , i.e. 95% of all men are shorter) was 184.1 cm tall in 1975, but 191.0 cm in 2000. According to examinations during the examination, the average height has risen continuously from 174 cm (born in 1938) to almost 180 cm. Since then, no clear increase has been observed. The height of women has decreased from 156 in 1956 to 166 cm in 1975. Here, too, no clear increase has been observed since then. The size of newborns has also increased: The proportion of children over 55 cm in length has increased from 3.4% in 1986 to 10.1% in 2001. The increased tendency to grow has led to an increase in the frequency of myopia by lengthening the eyeball.

This increase in size is problematic from a medical point of view insofar as the environment is not adjusted to this development. Obsolete standards cause ergonomic problems and as a result, for example, to poor posture .

The acceleration proves to be problematic in questions of the ergonomic design of motor vehicles, for example . When designing the vehicle, people sizes from the 5th percentile woman (only 5% of all women are shorter) to the 95th percentile man are taken into account. The acceleration is between 1.4 mm for the 5th percentile woman and 2.3 mm per year for the 95th percentile man. Their body length difference increased from 331 mm in 1974 to 350 mm in 1995. This makes it more and more difficult to design vehicles in such a way that all people can be accommodated equally cheaply in the vehicle.

Statistical surveys in the context of samples show that body size is dependent on social and regional origin. Accordingly, north German men are taller than south German. In terms of body size, the offspring of the social upper class significantly exceeds that of the basic class.

Different hypotheses were put forward to explain this acceleration:

  • Nutrition theory by Widukind Lenz 1959: Changes in diet through animal fat and protein-rich food, which increases the function of growth-promoting glands
  • Increased supply of stimuli through urban civilization (leisure activities ...)
  • Time-limited and dosed stress exposure in childhood
  • Changed climatic conditions
  • Changes in genetic predispositions through surgical obstetric interventions: The evolutionary trend towards an increase in intelligence leads to an increase in brain size at birth as a prerequisite for an increase in adulthood. The correspondingly larger head results in the obstetric complication of a disproportion between infant head size and maternal pelvic width, which was previously associated with high infant and maternal mortality. Obstetric interventions such as forceps and vacuum extraction (from the end of the 17th century) and caesarean section (from the end of the 19th century) have largely eliminated this possibility of complications. The frequency of taller children with larger heads allows the height to increase with faster development.

Development acceleration

Acceleration occurs when:

  • the individual development of the person in comparison with the respective age group in which they are, or
  • the development of a generation compared to previous generations

is advanced or accelerated. The change of teeth starts earlier. A particularly significant developmental acceleration is sexual acceleration, which means that puberty begins earlier. The premature hormonal change causes, for example:

  • increased self-assertion tendencies in boys
  • increased need for devotion and tenderness in girls
  • Eroticization of the environment
  • a shift in interests away from the family and towards the opposite sex

See also


  • Dieter E. Zimmer : Always bigger, bigger and faster In: Dieter E. Zimmer, Experiments of Life, Haffmans, Zurich 1989
  • Brigitte Melzer, Bernward Meier: The importance of acceleration for youth marketing, IJF Institute for Youth Research 1982
  • Warkentin, B .: On the question of the relationship between psycho-physical acceleration and modern obstetrics. In: Natal u. Frauenheilk. 50 (1990). Pp. 822-824.

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