In 1800 Jean Baptist Lamark proposed a coherent but wrong theory of evolution. Lamark proposed that offspring inherit the characteristics their parents use most. An example is the giraffe, that stretched high for leaves would produce offspring with longer necks. Or if your parents worked out often at the gym, you would be born with the ability to become more muscular. He also believed evolution was a slow process. Culver was an early paleontologist who believed that a species does not change. He also believed a species come and go in the fossil record. He stated these changes were related to catastrophes. Darwins theory relied on the process of natural selection. In his theory there were many giraffes of varying heights, that be related to different organisms through the process of sexual reproduction. Darwin stated all life competes in a struggle for life. In Lamarks theory he said that an organism such as the giraffe would have shorter necks and legs if it was a bad season when all vegetation in lower areas, that were easily reachable by the giraffes with shorter legs and necks had gone. The remaining giraffes were forced to stretch their necks to reach the food higher in the trees. He also stated that these giraffes would pass the traits of longer legs and necks would pass these traits to their offspring. These theories were believed to be the explanation for varying species of animals on earth. Lamarks theory for the varying species is not possible, and Darwins theory is believed to be the means of evolution.