Darwin – 2^ND Lecture

Natural Selection (definition based on three observations and an inference)

Heritable variation exists within any species

Some individuals will be better adapted than others

Far more young are born than can possibly survive

(infer) "Struggle for existence" must occur

Natural selection is a consequence of this "struggle" over generations

Alfred Wallace

Why did it take Darwin so long to complete "On the Origin of Species"?

He had two questions he could not answer

1. Where did variation come from and how is it inherited?

2. How do we get from one species to another