Seek Spirit, Savor Intellect

 book forthcoming

Evolution Evolving: What Everyone Needs to Know
By Patricia A. Williams

Table of Contents

1. Grasping the Essentials
2. Understanding Evolution
3. Calculating Genetics
4. Explaining Social Behavior
5. Synthesizing Biology
6. Appreciating Development
7. Seeing through Time
8. Creating a Fourth Synthesis

Conclusion

From the Introduction
As part of my graduate coursework in philosophy, I read Charles Darwin’s On the Origin of Species by Means of Natural Selection and fell in love. “This,” I said to myself, “is what I want to do with the rest of my life.” There is much to love. The book is a masterpiece of philosophical argument. It is also clearly written, filled with fascinating facts and evident affection for animals. It is also logical—a philosopher’s delight. Moreover, Darwin so well understood his own theory that contemporary philosophers and biologists working in the field of evolutionary biology often reread it annually for fresh understandings. Modern biology is evolutionary biology, and evolutionary biology today still derives many of its fundamental insights from Darwin.

Studies of evolution include both fact and theory. It is a fact that groups of organisms evolve, that is, they change over time. The evidence for the fact of evolution is everywhere. Many people think of the fossils that show the history of life on Earth. However, Darwin discovered evidence for evolution from his observations of animals living on islands. They represented different species, yet they all seemed related. He concluded they were related, that they evolved on the islands. Today perhaps the best evidence comes from genes. All organisms—bacteria, yeast, insects, reptiles, birds, and mammals (including us)—share some genes. About 3.8 billion years ago, a population of organisms lived that carried these genes. Every living thing possesses them.

Evolution is also a theory about causes. The main cause of evolution is natural selection. Natural selection is a force in nature that preserves some organisms and destroys others. Natural selection may be environmental, like drought that kills all the fish in a disappearing lake. It may also consist of interactions among species, like that between cat and mouse. Or it can occur within a single species, like mate choice by peahens that gave peacocks their famous tails. Natural selection is also well-supported with evidence. The evidence comes from experiments with living organisms in laboratories and from observations of nature.

This book is about major discoveries in biology and their impact on our understanding of evolution since Darwin published On the Origin of Species in 1859. At the same time, it is also about evolution as science, about whether it is good science, whether its new discoveries constitute good science, and whether they support Darwin’s original concepts.

Darwin’s work on evolution produced four major accomplishments. First, it provided a mechanism (natural selection) that explains how evolution occurs. Second, it united in one synthesis information from fields of biology that seemed separate. Third, it offered testable predictions. Fourth, it inspired new research in every field it touched, creating new publications, techniques, and institutions. It continues to inspire research today.

Most new discoveries after Darwin tended to support Darwin’s work. One, however, threatened to undo his synthesis. This was the rediscovery in 1900 of Mendel’s work on genes that proved inheritance discontinuous, whereas Darwin’s concept of gradual change seemed to imply that inheritance is continuous. However, biologists successfully combined Mendel’s discoveries with Darwin’s gradual evolution and declared Darwin’s synthesis restored under the name New Synthesis (or neo-Darwinism) in 1947. Nonetheless, the New Synthesis remained incomplete. A third synthesis called sociobiology, begun in 1964, restored two other elements from Darwin’s original synthesis—the importance to evolution of relatives and of sexual selection. Now only developmental biology remains excluded. As of the 1980s, biologists began a forth synthesis under the name of evo-devo—evolutionary developmental biology. It is a work in progress.

by Patricia A. Williams

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