I noted a couple of days ago that the National Academy of Sciences and the Institute of Medicine released “Science, evolution, and creationism.” Catching up on my reading this morning I find that Francisco Ayala, who chaired the committee that produced the report, has an editorial about the report in the most recent issue of the Proceedings of the National Academy of Sciences USA. Here are a few key passages:
Biological evolution is the central organizing principle of modern biology. Evolution provides a scientific explanation for why there are so many different kinds of organisms on Earth and gives an account of their similarities and differences (morphological, physiological, and genetic). It accounts for the appearance of humans on Earth and reveals our species' biological connections with other living things. It provides an understanding of the constantly evolving bacteria and viruses and enables the development of effective new ways to protect ourselves against the diseases they cause. Evolution has made possible improvements in agriculture and medicine and has been applied in many fields outside biology, including forensics and software engineering; it has stimulated chemists, for example, to use the principles of natural selection for developing new molecules with specific functions....
Biological evolution is part of a compelling historical narrative that scientists have constructed over the last few centuries. The narrative begins with the formation of the universe, the solar system, and the Earth, where conditions occur suitable for life to evolve. There are theories that seek to account for how life originated on Earth, but none of them has gathered enough supporting evidence to be generally accepted by scientists. But natural selection, discovered by Darwin, has been convincingly demonstrated as the process that accounts for the adaptive configuration and function of organisms (for their “design”). Darwin's greatest contribution to science is not that he accumulated evidence demonstrating the evolution of life, but that he discovered natural selection, the process that accounts for the design of organisms and their wonderful adaptations to survive and reproduce in the environments where they live, including wings for flying, legs for running, eyes to see, and kidneys that regulate the composition of the blood.
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Science and religion concern different aspects of the human experience. Scientific explanations are based on evidence drawn from examining the natural world and rely exclusively on natural processes to account for natural phenomena. Scientific explanations are subject to empirical tests by means of observation and experimentation and are subject to the possibility of modification and rejection. Religious faith, in contrast, does not depend on empirical tests and is not subject to the possibility of rejection based on empirical evidence. The significance and purpose of the world and human life, as well as issues concerning moral and religious values, are of great importance to many people, perhaps a majority of humans, but these are matters that transcend science.
I think Ayala's wrong that “Darwin's greatest contribution to science is not that he accumulated evidence demonstrating the evolution of life, but that he discovered natural selection....” True, evolutionary ideas were around well before Darwin wrote On the Origin of Species,1 but it wasn't until the Origin appeared that evolution became widely accepted among scientists. And when the 50th anniversary of the Origin's publication was celebrated in the early 20th century, many biologists doubted the importance of natural selection.
Even later in 1928, Nordenskiöld wrote in his history of biology
Natural selection is certainly retained in principle by some students of heredity ... but it is really of no practical importance; the phenomenon and it is therefore not possible to fit it into a subject of research that is based on exact observations. (Nordenskiöld, The History of Biology, Alfred A. Knopf, New York, NY)
Nordenskiöld was wrong of course, as the Modern Synthesis would soon show, but given the history of biology, it's hard to argue that Darwin's co-discovery of natural selection2 is his greatest contribution. His amassing of evidence from biogeography, comparative anatomy, and systematics that all living things share a single common ancestor is a contribution at least as great as that of discovering the theory of natural selection.
1Including ideas that his grandfather, Erasmus Darwin, put forward.
2Alfred Russell Wallace co-authored the original paper describing the mechanism of natural selection.
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