| Chapter 1: | Introduction |
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New Ways of Thinking
Until recently, aggression was assumed to be a major force in the evolution of many species. If a male is strong and aggressive enough to be able to mate with most of the females in a group, his genome will obviously be important to the group’s future. Competition was presumed to be pervasive. The Mermaid’s Tale: Four Billion Years of Cooperation in the Making of Living Things, by Kenneth Weiss and Anne Buchanan (2009), however, tells a different story. In the past, evolution was thought of as something large that happens over hundreds or thousands of years. No one, even Charles Darwin, knew exactly how this was carried out in the short term. Weiss and Buchanan argued that natural selection is one way, but only one way, by which evolution can proceed. Evolution is, rather, a multidimensional process.
Evolution can occur because of environmental change. Consider a northern pond surrounded by forest. In natural succession over the years, the pond slowly filled with reeds, then gradually with more terrestrial plants, and finally with saplings. Fish and frogs that lived in the pond disappeared, to be replaced by woodland creatures such as mice and shrews. One population of animals has “won” and another has “lost,” but there has been no contact between them.
Another way is through organismal selection, meaning when members of a species select a new environment (although usually not consciously). Perhaps part of a forest in North America may be clear-cut, leaving areas of scrub and brush behind. Deer will soon move into this new region. Again, this could lead in the future to an evolutionary change.
Or, members of a species may spread out over a wide area and, by chance, become separated into two factions. One group may even have swum to an island while another remained on the mainland. In time, with random mutations occurring in each group, these populations will eventually be unable to interbreed, or they may not want to do so. Again, there has been no competition.