Today we celebrate the 200th birthday of Charles Darwin, the scientist who brought the world irrefutable evidence of evolution and introduced natural selection, the process by which it occurs.

Darwin is the only scientist who we honor with a day, despite many others who made significant discoveries. His work had the greatest impact because it provided an evidence-based alternative to belief-based views on the origins of life.

In 1831, at 22, Darwin was hired as companion to the captain of a British sailing vessel, whose task was to survey the coast of South America. When Darwin left on this five-year voyage, he shared the prevailing view of his time that Earth’s variety of life forms had been placed by God in their present form. During the voyage, Darwin assumed the role of ship’s naturalist. His observations served as the basis for the 1859 publication “Origin of Species,” in which he detailed the findings that catalyzed his realization that organisms change over time. Though renown for his work on the Galapagos Island finches, Darwin’s observations of fossils along the eastern coast of South America had an immediate impact on his views. There he found fossils of giant ground sloths and armadillos, absent from the present-day fauna, but strikingly similar to smaller modern versions. Darwin’s interpretation that these extinct animals were ancestors of the present-day forms was at least as reasonable as the idea that God had placed them there separately. In “Origin of Species,” Darwin also introduced natural selection.

In natural selection, a life form less suited to an environment either dies before reproducing or reproduces less than a better-suited version. Consequently, in time a population will contain more of the better-suited form. The environment determines the direction of change. Today, we observe many examples of natural selection including the emergence of antibiotic-resistant bacteria and drug-resistant HIV. Understanding the evolution of disease and developing appropriate treatments is one example of the importance of this concept in our everyday lives.

It is puzzling that after 150 years of scientific corroboration of Darwin’s ideas, recent legislation undermining the teaching of evolution in U.S. schools has been proposed in seven states by creationists — proponents of belief-based views on life’s origins. Creationists have challenged the teaching of evolution ever since the trial of science teacher John Scopes in 1925 in Tennessee. Creationism’s changing titles have been “scientific creationism” in the 1970s, “intelligent design” in the 1980s and, most recently, “academic freedom.” Current legislative proposals contend that evolution and natural selection lack significant scientific support. By presenting evolution as a theory in crisis, supporters hope to open the door for the teaching of creationism alongside or in place of evolution in America’s science curriculum.

It is perhaps imperative then, given the perseverance of creationism in the U.S., that we celebrate Darwin and the importance of his ideas to science and society today. Indeed, many religious organizations recognize that there is no conflict between the acceptance of evolutionary processes and the existence of faith. Religion has a role to play in the celebration of Earth’s diversity. In Darwin’s words, “There is grandeur in this view of life … from so simple a beginning endless forms most beautiful, most wonderful have been, and are being, evolved.”

Susan Swensen is a professor and chair of the biology department.
E-mail her at sswensen@ithaca.edu.