Contributors: Steven M. Stanley — Chair, Patricia Kelley, Richard Bambach, George Fisher, James Skehan, Don Wise, David Dunn.
The Geological Society of America recognizes that the evolution of life stands as one of the central concepts of modern science. Research in numerous fields of science during the past two centuries has produced an increasingly detailed picture of how life has evolved on Earth.
The rock record is a treasure trove of fossils, and by 1841, eighteen years before Charles Darwin published On the Origin of Species, geologists had not only assembled much of the geologic time scale from physical relationships among bodies of rock, but they had also recognized that fossils document profound changes in life throughout Earth's history. Darwin showed that biological evolution provides an explanation for these changes. Since the time of Darwin, geologists have continued to uncover details of life's history, and biologists have continued to elucidate the process of evolution. Thus, our understanding of life's evolution has expanded through diverse kinds of research, much of it in fields unknown to Darwin such as genetics, biochemistry, and micropaleontology. In short, the concept of organic evolution has not only withstood the test of time — the ultimate test of any scientific construct — but it has been greatly enriched.
In recent years, certain individuals motivated by religious views have mounted an attack on evolution. This group favors what it calls "creation science", which is not really science at all because it invokes supernatural phenomena. Science, in contrast, is based on observations of the natural world. All beliefs that entail supernatural creation, including the idea known as intelligent design, fall within the domain of religion rather than science. For this reason, they must be excluded from science courses in our public schools.
This separation of domains does not mean that science and religion are fundamentally incompatible. Many scientists who conduct research on the evolution of life are religious, and many major religions formally accept the importance of biological evolution.
Misinterpreting the Bible's creation narratives as scientific statements, many creationists go so far as to attack the validity of geologic time — time that extends back billions of years. "Deep time" is the foundation of modern geology. It was actually well established, though not quantified, by geologists decades before Darwin published his ideas or most scientists came to accept evolution as the explanation for the history of life. Furthermore, thousands of geologists employing many new modes of research refined the geologic time scale during the Twentieth Century. Near the start of that century, the discovery of naturally occurring radioactive substances provided clocks for measuring actual ages for segments of the geologic record. Today, some billion-year-old rocks can be dated with a precision of less than a tenth of one percent. Moreover, modern geologists can identify particular environments where sediments that are now rocks accumulated hundreds of millions of years ago: margins of ancient oceans where tides rose and fell, for example, and valley floors across which rivers meandered back and forth, and ancient reefs that grew to thicknesses of hundreds of meters but were built by organisms that could not have grown faster than a few millimeters a year. By studying the fossil record that forms part of this rich archive of Earth's history, paleontologists continue to uncover details of the long and complex history of life.
Acceptance of deep time is not confined to academic science. If commercial geologists could find more fossil fuel by interpreting the rock record as having resulted from a single flood or otherwise encompassing no more than a few thousand years, they would surely accept this unconventional view, but they do not. In fact, these profit-oriented geologists have joined with academic researchers in refining the standard geologic time scale and bringing to light the details of deep earth history.
Modern studies of the evolution of Earth and its life are not only aiding us in the search for natural resources, but also helping us to understand how the Earth-life system functions. Annual layers of ice in the Greenland glacier, for example, range back more than a hundred thousand years. These ice records warn that Earth's climate may change with devastating speed in the future. The geologic record also reveals how various forms of life have responded to past environmental change, sometimes migrating, sometimes evolving, and sometimes becoming extinct. In the present world, bacteria are now evolving rapidly in ways that render antibiotics ineffective; to respond to bacterial evolution, we must understand evolution in general.
The immensity of geologic time and the evolutionary origin of species are concepts that pervade modern geology and biology. These concepts must therefore be central themes of science courses in public schools; creationist ideas have no place in these courses because they are based on religion rather than science. Without knowledge of deep time and the evolution of life, students will not understand where they and their world have come from, and they will lack valuable insight for making decisions about the future of their species and its environment.