Who was Jean-Baptiste Lamarck?

Jean-Baptiste Lamarck (1744–1829) was a pioneering French biologist and naturalist. He is best known for proposing the theory of Lamarckism in 1809, which suggested that physical changes acquired by an organism during its lifetime—such as the enlargement of an organ through increased use—could be inherited by its offspring.12

Lamarck believed that environmental changes created new needs (besoins) in animals, leading to new behaviors and the use or disuse of specific body parts. He famously used the example of a giraffe stretching its neck to reach high leaves, arguing that this habit caused the neck to grow longer over generations.3

While his work significantly influenced 19th-century evolutionary thought, Lamarckism is considered scientifically inaccurate today. Modern genetics and evolutionary theory have discredited the idea that such acquired characteristics are passed on to subsequent generations, as there is no biological mechanism for transferring these somatic changes to sex cells.123