What is Lamarckian?

Lamarckian refers to the evolutionary theory proposed by Jean-Baptiste Lamarck, which suggests that organisms can pass on traits acquired during their lifetime to their offspring. This concept is often summarized by the idea that "use and disuse" of certain body parts can lead to changes that are inherited. While Lamarck's ideas were influential in the early study of evolution, they have largely been supplanted by Darwinian natural selection and modern genetics, which emphasize heritable genetic variations rather than acquired characteristics.