Jean Baptiste De Lamarck was a French naturalist who is remembered for his contributions to the study of evolution. Lamarck believed all living life forms evolved every generation and would use these changes to adapt to their environment.
Lamarck believed evolution was a constant process among all living animals. He theorized that organisms would evolve into more complex versions of themselves and would continue to do so until they had reached a state of perfection.
While Charles Darwin's theory of natural selection would eventually become the basis of evolutionary thought, Lamarck's early work in the field was the first to recognize the impact the environment could have on living species. The basis of Lamarck's theory was based on the idea that organisms altered their behaviors and habits because of environmental changes. Lamarck believed these changes in behavior would alter an organism's body and would be passed on to the next generation.
Lamarck used giraffes as a prominent example to explain his theory. He argued that giraffes developed their long legs and necks because of generations of having to reach high tree leaves. Giraffes who stretched their necks and legs to reach high leaves would permanently acquire these traits and pass them on to their offspring.