Jean-Baptiste Lamarck (August 1, 1744 – December 18, 1829) was a French naturalist who proposed one of the first theories of evolution. He postulated a principle called inheritance of acquired characteristics, that an animal was able to change a characteristic during its lifetime depending on its behavior, and that these changes would be passed onto its offspring resulting in speciation. For example, if a giraffe attempted to eat the leaves off the top of a tree it would be constantly stretching its neck, resulting in both a longer neck for itself and that this characteristic would be passed onto its young.
Lamarckian evolution was upheld for decades in the 1900s by Trofim Lysenko, head of genetic and biological study within the Soviet Union, until he was discredited along with his pseudoscience in the 1960s. Due to observed microevolutionary changes in organisms related to Lamarkism, the Larmarkism school of evolutionary thought has seen a bit of a resurgence (see: Lamarckism).
The biblical creation model, however, still has the weight of evidence supporting it (see: Creation science).