Darwin's Theory of Evolution - Natural Selection
While Darwin's Theory of Evolution is a relatively young archetype, the evolutionary worldview itself is as old as antiquity. Ancient Greek philosophers such as Anaximander postulated the development of life from non-life and the evolutionary descent of man from animal. Charles Darwin simply brought something new to the old philosophy -- a plausible mechanism called "natural selection." Natural selection acts to preserve and accumulate minor advantageous genetic mutations. Suppose a member of a species developed a functional advantage (it grew wings and learned to fly). Its offspring would inherit that advantage and pass it on to their offspring. The inferior (disadvantaged) members of the same species would gradually die out, leaving only the superior (advantaged) members of the species. Natural selection is the preservation of a functional advantage that enables a species to compete better in the wild. Natural selection is the naturalistic equivalent to domestic breeding. Over the centuries, human breeders have produced dramatic changes in domestic animal populations by selecting individuals to breed. Breeders eliminate undesirable traits gradually over time. Similarly, natural selection eliminates inferior species gradually over time.
In the years after his service during the French military campaign in Germany in the 1760s, Jean-Baptiste Lamarck studied medicine and botany. This led to a job at the Jardin des Plantes royal botanical gardens, which was soon reorganized into the Musée National d'Histoire Naturelle. At the museum, Lamarck became the professor of invertebrates, where he coined the term "invertebrate" and succeeded in advancing classification of invertebrate animals. During this time, Lamarck published a variety of work on invertebrates, paleontology, physics and even meteorology, with his first writings on evolution finally coming to publication in the early 19th century.
In his book "Philosophie zoologique," Lamarck detailed his theory of evolution, which stated that organisms constantly evolved with each generation. He supplemented this claim by declaring two laws for evolution. The first law is that environmental change causes an organism to behave differently, thus resulting in use or lack of use of a given organ. Increased use causes said organ to grow while lack of uses causes the organ to shrink--a change that would occur over several generations. Lamarck's second law dictated that these changes were traits that were inherited from a parent organism.
Compared to Darwinism
Both Darwin and Lamarck believed that organisms evolve due to environmental change, and both even used the same evidence for their theories, like the variety of organisms that occur through controlled breeding and the presence of vestigial organs in animals. Darwin even accepted Lamarck's belief that such changes could be inherited.
However, Darwin hypothesized that natural selection was responsible for the proliferation of certain characteristics, while Lamark did not find natural selection to be very important, as he did not believe in the possibility of extinction. Rather, he believed in constant evolution into more complex forms, and that species only vanished because they had evolved into something else. As for a reason why simpler organisms like protists continue to exist, Lamarck attributed their presence to spontaneous generation.
So, the difference was that Darwin believed in natural selection and Lamarck did not believe that natural selection was that important.
Churches found Darwin's theory to be unacceptable because if his theory were to be true, that would mean there was no God. Did we evolve from monkeys? or is there a God?
I know, long!! but, I hope this helps you with your project :)