Chapter 4: Natural Selection Summary and Analysis

Natural selection is a process that is the result of the ideas expressed in the previous two chapters: variations that occur in the wild and the struggle for survival among all organisms. While perhaps most variations that occur are not helpful for surviving, very rarely, a variation does occur which helps an organism to survive and reproduce. Given that many more organisms are produced than can survive, those traits which are helpful in surviving will tend to be passed on, while those traits which are not helpful will tend to be weeded out. If a variation is neither helpful nor unhelpful, it is not subject to natural selection.

The process of natural selection can be illustrated by considering a region that undergoes a dramatic change in climate. The result of this would surely be to drastically change...