The development of evolution theories

Towards the end the 19th century Weismann (1834 – 1914) debunked Lamarck’s belief according to which features acquired during the course of a generation were transferable to descendents and identified in the mix of different heritages, as happens with sexual reproduction, which is the main cause of biological variability. Thus a relationship between evolution and genetics was established. The first genetic contributions to evolutionism came from two researchers, Hardy and Weinberg who in 1908, each one of them on his own, did a statistic study on gene distribution among a population and on the necessary conditions to avoid variations between one generation and the next one. The opposite conditions, in fact, can constitute a number of evolution factors such as :

  • Gene mutations
  • Advantage of individuals with a specific genetic makeup compared to others
  • Numeric limitation of the population
  • Gene migration between neighbouring populations

Around 1920 some geneticists among whom Fisher, Wright and Haldane, did a statistic study of the evolution issue, including Hardy’s and Weinberg’s theories in a broader spectrum of causes that can modify genetic balances in a certain population and influence its evolution.
Thus natural selection became an evolution factor and certain basic elements of Darwin’s theory were upheld. Mathematical models calculated  by population genetics have been proved both in laboratory experiments as well as in different natural habitats thus providing final evidence.

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