I just found this document on my computer. It is a short synopsis of the history of evolutionary thought that I wrote for a class in my first year of grad school. It is not perfect or complete, but I thought it was worth posting. Please add corrections or comments below.
The theory of evolution by Darwinian natural selection is of critical importance to modern paleontology, and the field of paleontology has had a decisive role in the justification of the theory. Early ideas on the natural community of life followed Plato’s Principle of Plenitude. This principle essentially stated that everything that could exist did in fact exist, and that forms could not be created nor could existing forms be destroyed. This principle was at the heart of the idea of the scala naturae, or the Great Chain of Being, which envisioned the natural world as consisting of a hierarchical ordering of organisms from the simplest to the most complex (read most perfect), from the creeping slimes to the crowing achievement of creation, humans. Humans were merely a step below cherubim and other various categories of angels.