Facts on File Ltd Hodge, R: Evolution

The theory of evolution can be observed anywherefrom exotic tropical rain forests to our own backyardsand is based on three main principles: heredity, variation, and selection. In the 19th century, Charles Darwin and Alfred Russel Wallace sought to explain how these processes work together to produce new species. Evolution provided the first scientific system to investigate the origins and relationships of living creatures, and today it serves as a grand unifying theory, explaining facts that cannot really be accounted for in any other way.