The Effect of External Influences upon Development

August Weismann (1834-1914) was a German biologist renowned for his significant contributions to the field of evolutionary biology and embryology. Born on January 17 in Frankfurt am Main, Germany, Weismann embarked on a journey in science that led him to challenge preconceived notions about inheritance and development. He is most notably attributed with formulating the 'germ plasm' theory of heredity, which starkly contrasted the then-popular Lamarckian view of the inheritance of acquired characteristics. This theory posited that the hereditary information is carried only in the germ cells, and somatic cells do not pass on traits to subsequent generations, an idea that laid foundational groundwork for modern genetics. Weismann's extensive research is encapsulated in his influential work, 'The Effect of External Influences upon Development' (1894), wherein he argued against the hypothesis that environmental changes during an individual's lifetime could directly affect the genetic material. His scientific endeavors and rigorous approach greatly impacted the understanding of natural selection and heredity, carving a pivotal role for Weismann within the scientific community. His literary style is characterized by meticulous detail and clarity of thought, making his complex theories accessible to a broad audience of contemporaries and future scholars. Weismann's legacy persists through his contributions which continue to inspire and inform biological research and evolutionary thought.