Jean-Baptiste Lamarck coined the idea of organisms changing. He hypothesized that traits acquired during the lifetime of the being in question could be passed on to its offspring. The two main ideas in his theory of evolution are:
1) Use and disuse - Individuals lose characteristics they do not require (or use) and develop characteristics that are useful.
2) Inheritance of acquired traits - Individuals inherit the traits of their ancestors.
Darwin's theory of evolution boils down to "Survival of the Fittest". I believe that Lamarck paved the way to this theory. A popular example of "Lamarckism" is a giraffe stretching its neck to reach eaves in high trees eventually strengthening and lengthening it's neck. Darwin believed that the "strongest" survived and went on to mate and reproduce. The giraffe with the longest neck would be able to eat more, which meant when all the lower leaves were gone and the giraffes with the shorter necks were going hungry - possibly starving to death- the giraffe with the longer neck was still able to get the food it needed to live. This animal was the one that was able to live on, mate, and produce other giraffes. The offspring of the giraffes with the longer necks would also have this trait most likely.
Lamarck's theories were ignored or heavily scrutinized while he was still alive. He was never made famous during his lifetime for his work. During his lifetime Lamarck named a large number of species- most of them sea or water life. He has almost 150 (give or take) species named after him. Lamarck published "Hydrogeologie" in 1802 and was the first person to use the term "biology" in the modern sense.
I do not believe that Darwin could have developed his theory without being influenced by Lamarck. I think that he was really on the right path with things and if Darwin didn't have Lamarck's theory to learn from, he would not have evolved his theory into what we know today. Lamarck seems to have been ahead of his time when he came up with what he did. If the world was in a different place I think he really could have ran with the idea and maybe we would be learning about Lamarck as the big evolutionist instead of Darwin.
The Church was against Darwin because he was basically in their face saying that God is not solely responsible for creating beings...that we were evolved. This goes against everything that the huge empire known as the Church believed. During those times the Church seemed like it was the end all. Everything they said or thought was the word. There were no if's, and's or but's. Darwin was going against the flow with his scientific opinion and was essentially telling all these people they were wrong. The Vatican has been refining its beliefs on evolution throughout the years but it is a slow and steady process.
http://www.ucmp.berkeley.edu/history/lamarck.html
