Lamarckism was developed by Jean-Baptiste de Lamarck. He based his ideas, to some extent, on those of Erasmus Darwin, the grandfather of Charles Darwin. Lamarckism says that individuals do not only pass on the things they received from their parents, but also some things they experienced during their lifetime. As an example, he cited giraffes. Giraffes, which have long necks, must have evolved from ancestors with much shorter necks. His idea was that adults needed to stretch their neck to reach leaves from high branches. Therefore, he thought, the children inherited longer necks. This idea is called "the inheritance of acquired characteristics".