Overview

By 1900 scientists had been trying to explain how natural selection worked for 40 years. The idea proposed by Charles Darwin (1809-1882) was accepted, but the mechanism was unclear. When they turned to microscopic investigation, identifying structures and processes within cells, the mechanism of natural selection became clear. Scientists studied specific traits, followed populations in the wild, and applied chemical and statistical techniques and principles to the problem. By 1950 natural selection was supported by the new field of genetics, and DNA was about to be deciphered. The focus of genetics then turned to the structural makeup of the gene. By mid-century this would revolutionize medicine as well as genetics. It would lead to manipulation of genes, gene therapies, identification of individuals by their DNA, replacement of defective genes, and identification and location of specific genes.

Background

Darwin's theory of...