Working Group on Teaching Evolution, National
Academy of Sciences
ISBN: 0-309-53221-3, 150 pages, 8.5 x 11, (1998)
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Teaching About Evolution and the Nature of Science http://www.nap.edu/catalog/5787.html 1
Why Teach Evolution?
hy is it so important to teach evolution?
After all, many questions in biology can be answered without mentioning evolution: How do birds fly? How can certain plants grow in the desert? Why do children resemble their parents? Each of these questions has an immediate answer involving aerodynamics, the storage and use of water by plants, or the mechanisms of heredity.
Students ask about such things all the time.
The answers to these questions often raise deeper questions that are sometimes asked by students: How did things come to be that way? What is the advantage to birds of flying? How did desert plants come to differ from others? How did an individual organism come to have its particular genetic endowment? Answering questions like these requires a historical context—a framework of understanding that recognizes change through time.
People who study nature closely have always asked these kinds of questions. Over time, two observations have proved to be especially perplexing. The older of these has to do with the diversity of life: Why are there so many different kinds of plants and animals? The more we explore the world, the more impressed we are with the multiplicity of kinds of organisms. In the mid-nineteenth century, when Charles
Darwin was writing On the Origin of
Species, naturalists recognized several tens of thousands of different plant and animal species. By the middle of the twentieth century, biologists had paid more attention
to less conspicuous forms of life, from insects to microorganisms, and the estimate was up to 1 or
2 million. Since then, investigations in tropical rain forests—the center of much of the world’s biological diversity—have multiplied those estimates at least tenfold. What process has created this extraordinary variety of life?
The second question involves the inverse of life’s diversity. How can the similarities among organisms be explained? Humans have always noticed the similarities among closely related species, but it gradually became apparent that even distantly related species share many anatomical and functional characteristics. The bones in a whale’s front flippers are arranged in much the same way as the bones in our own arms. As organisms grow from fertilized egg cells into embryos, they pass through many similar developmental stages. Furthermore, as