1. Thomas Malthus 1798 published Essay on the Principle of Population
Gave Darwin idea that populations produce more offspring than can survive because populations increase faster than earth can support
This would mean that natural selection would be “the survival of the fittest” because there were not enough resources for every organism to survive.

2. Lamarck
Lamarck published a theory of evolution in 1809 (same year Darwin was born). He explained the mechanism of evolution with two principles.
The use or disuse of body parts leads to their development or deterioration, acquired characteristics can be inherited.

3. Charles Lyell
Proposed geological theory of uniformitarianism which is different from catastrophism.
Uniformitarianism- the events in the past that formed the Earth are still at play today and are a gradual process
Catastrophism – the other popular viewpoint of the Earth’s structure was that the Earth remained constant for thousands of years. Then, catastrophes would occur that would change the Earth. After which, it would go back to being the same for extended periods of time.
Principles of Geology was published, Darwin read and agreed with the findings.

4. Charles Lyell Continued
He studied sedimentary rock and how the layers (stata) of the Earth form.
He said that these processes take thousands of years to occur and those same processes continued to occur today.
Darwin used this information to conclude that if the different layers of the Earth take thousands of years to form, then the different fossils found in each layer must’ve taken thousands of years to change or evolve.

5. Charles Lyell Cont.

6. Darwin and Wallace
In the 1830’s Darwin starts compiling his work and another scientist, Alfred Wallace, was also working on a theory of natural selection.
Before publishing his findings, Wallace sends a copy of his work to Darwin in 1858.
To Darwin’s surprise, Wallace has formulated a very similar theory.

7. Both findings were presented to the Linnaean Society in 1858.
Darwin’s Origin of Species was published in 1859 (yes! 20 years after he wrote it!), Wallace will continue his travels and research
Wallace’s theory and name will forever stand in the shadow of Darwin and the theory of evolution.