Jean-Baptiste Lamarck (1744-1829) was one of the first people to study the overall evolutions of populations from a scientific viewpoint. He made many contributions to the understanding of how groups of organisms related to each other, but is most prominently remembered for his incorrect idea of the "inheritance of acquired traits."

In this theory, environmentally-induced changes are passed on to offspring. Example: If a giraffe stretches its neck to reach high leaves, then its offspring will have longer necks. Or: Blacksmiths have strong muscles through heavy use -- Lamarckian theory implies that children of blacksmiths would be born with big muscles.

We know now that this idea is wrong and that in particular the causality is wrong -- as we shall see.

But Lamarck's ideas did make an important contribution to science in the early 1800s, namely by suggesting that organisms could change their shapes and forms and functions over time. Prior to Lamarck, it was thought that all organisms presently had the shape they always had and always will.

http://www.necsi.org/projects/evolution/lamarck/lamarck/lamarck_lamarck.html

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