The Pillars of Darwinism

This month marks the 150th anniversary of the publication of Charles Darwin’s On the Origin of Species . The evolutionary theory he presented in that great book rests on two pillars: the idea of descent with modification, and the idea of natural selection. amp#160;

Darwin believed that present-day organisms are descendants of much simpler ancestors: they are the products of unbroken lines of heredity that stretch back to the origin of life. Today, we have a mass of evidence, ranging from studies of ancient fossils to the latest discoveries of molecular biology, that supports this theory.amp#160;

Darwin, however, did not invent the idea of descent with modification. Fifty years earlier, Jean-Baptiste Lamarck had suggested that living things are products of a long historical process of transformation. But the evolutionary mechanisms he proposed, which included the inheritance of characteristics induced by the environment, never found favor.amp#160;