Sierra College Department of Biological Sciences

Discover the Biological Sciences

The introductory information for this site has been contributed as a joint assignment by students in Bio. Sci. 10.

Evolution - Darwinism

By: Jacqueline Vincent

Darwinism seems to have two meanings, his ideas about evolution and his concept of natural selection. Darwin believed that there was unity in life, that all organisms were related through descents from the past. As these organisms came in contact with a variety of habitats over millions of years, they adapted to there environment. Darwin viewed life like a tree, with branches that re-branched all coming from a common truck. The evolutionary tree is common in all lines of evolution. That all species are related and share similar characteristics, that they have all came to be from different branches of the same tree. Natural selection and adaptation centers on how individual species adapt to their environments by natural selection. Natural selection boils down to “survival of the fittest”. If a species has inherited the right traits to survive in its environment, it will produce more offspring’s, then say the less fit species. This will ensure that the more favorable traits will survive and the unfavorable traits will die off.

The most cited example of Natural Selection in Action is the English peppered moth, Biston betularia. It is found in the midlands of England and there are two varieties that are different in color, one is light with splotches of pigment and the other is dark. The light one feeds at night and sleep during the day, they are camouflaged because of their light color. The dark moth is very noticeable and is easy pray for birds. The dark moth was rare before the Industrial Revolution, most likely because of their color; they were less likely to reproduce. The pollution from the Industrial Revolution darkened the land in the late 1800s, after which they would see more dark moths. The light moths became easy pray for the birds because the land was darker and they were easier to see. At the turn of the century, the population of moths was mostly dark. In the case of the Biston, it demonstrates that natural selection operations in the present and those organisms adapt to their environment.

If you would like more information on Darwinism go to the following websites;,, or read Descent with Modification: A Darwinian View of Life, Campbell, N, Biology, 3rdEd. Benjamin/Cummings Publishing, 1993.

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