Social Science Darwin and Natural Selection

Most educated people in Europe and the Americas during the 19th century had their first full exposure to the concept of evolution through the writings of Charles Darwin. Clearly, he did not invent the idea. That happened long before he was born. However, he carried out the necessary research to conclusively document that evolution has occurred and then made the idea acceptable for scientists and the general public. This was not easy since the idea of evolution had been strongly associated with radical scientific and political views coming out of post-revolutionary France. These ideas were widely considered to be a threat to the established social and political order. At his father's direction, Charles Darwin started university at 16 in Edinburgh, Scotland as a medical student. He showed little academic interest in medicine and was revolted by the brutality of surgery. He dropped out after two years of study in 1827. His father then sent him to Cambridge University in 1828 to study theology. It was there that his life's direction took a radical change. He became very interested in the scientific ideas of the geologist Adam Sedgwick and the naturalist John Henslow with whom he spent considerable time collecting specimens from the countryside around the university. At this time in his life, Darwin apparently rejected the concept of biological evolution, just as his mentors Sedgwick and Henslow did. However, Darwin had been exposed to the ideas of Lamarck about evolution earlier while he was a student in Edinburgh. (Endler 52-95)

Darwin came to understand that any population consists of individuals that are all slightly different from one another. Those individuals having a variation that gives them an advantage in staying alive long enough to successfully reproduce are the ones that pass on their traits more frequently to the next generation. Subsequently, their traits become more common and the population evolves. Darwin called this "descent with modification."

The Galápagos finches provide an excellent example of this process. Among the birds that ended up in arid environments, the ones with beaks better suited for eating cactus got more food. As a result, they were in better condition to mate. Similarly, those with beak shapes that were better suited to getting nectar from flowers or eating hard seeds in other environments were at an advantage there. In a very real sense, nature selected the best adapted varieties to survive and to reproduce. This process has come to be known as natural selection.

Darwin did not believe that the environment was producing the variation within the finch populations. He correctly thought that the variation already existed and that nature just selected for the most suitable beak shape and against less useful ones. By the late 1860's, Darwin came to describe this process as the "survival of the fittest." This is very different from Lamarck's incorrect idea that the environment altered the shape of individuals and that these acquired changes were then inherited.

Nineteenth century critics of Darwin thought that he had misinterpreted the Galápagos ...