August Weismann

Born in Frankfurt am Main in 1834 and later based in Freiburg, August Weismann was a German biologist whose work had a lasting impact on evolutionary thought. He became director of the Zoological Institute and the first professor of zoology at Freiburg, building a reputation as a careful researcher and a strong defender of Darwinian evolution.

Weismann is best known for his germ-plasm theory, which drew a sharp line between the reproductive cells that pass hereditary information to the next generation and the rest of the body. By arguing that acquired characteristics are not inherited, he challenged ideas associated with Lamarckism and helped lay conceptual groundwork for the later development of genetics.

Today he is often remembered as one of the founders of genetics and as one of the most important evolutionary theorists of the 19th century. He died in 1914, but his ideas remained influential because they pushed biology toward a clearer, more modern understanding of heredity.