Charles Lyell
1. Charles Lyell was a contemporary (1797-1875) and friend of Charles Darwin. He began his education as a lawyer but switched his interest toward geology and is now considered the founder of modern geology. His developments in geology are recognized now as the theory of uniformitarianism.
2. Uniformitarianism is somewhat of a response over and against the reigning hypothesis of its day- catastrophism. What catastrophism asserted was essentially that the geological forces that shaped the earth were much more 'catastrophic' in earlier history than they were in modern times, and most proponents of this view sought to explain it with stories like the flood of Noah from the Judeo-Christian Bible. However, Lyell was not convinced and developed uniformitarianism which essentially was his assertion that the geological forces that are seen in the modern day, such as erosion from water and wind, are quite similar to those that would have been shaping the earth throughout its history. Consequently, this also led him to the conclusion that the earth must be incredibly old- much older than 'catastrophists' would say- because these less catastrophic forces take far longer to create such changes as valleys and mountains (rather than, lets say, a meteor strike).
3. Being friends with Darwin, Charles' work certainly impacted Darwin's study. The point from the list that I would say most closely correlates with Lyell's work is "Individuals do not evolve. Populations do." What I construe from this is that there is no specific change within any given individual organism and changes must occur over more than one reproductive cycle. Given that Darwin thought that adaptation must occur over longer periods of time, he may have gained this insight from Lyell's conclusions of an older earth. Also, given that Darwin spent much of his time studying in tropical climates, he could have known that sea turtles live very long lives, and for any positive adaptable traits to be passed down there would have to be numerous mating cycles for any significant part of the population to posses those traits.
4. I think that Darwin certainly could have developed his theory of natural selection without the influence of Lyell, though it may have taken him much longer to come to the conclusions of natural selection regarding time span. Nevertheless, given the sea turtle example from above, I think he could have come to the same conclusion through a different manner.
5. A major stumbling block of catastrophism Darwin's day (and arguably our own) is the belief that all of the earth's current organisms were created in their current form and had no origin but that of the divine. Darwin's conclusions were quite contrary to this and he encountered much friction in his attempts to publish. In fact, it took him quite a long time to finally publish his ideas after he had taken his initial voyage aboard the Beagle.
