A New View of Evolution

There have been lots of new books about evolution in the past decade or so. I tend to divide them into three categories:

1. The Standard View: These are books that basically support the Modern Synthesis with some small tweaks here and there. They do not advocate major shifts in the way we look at evolution. Books by Richard Dawkins (The Greatest Show on Earth: The Evidence for Evolution), Jerry Coyne (Why Evolution Is True), Sean B. Carroll (Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom, The Making of the Fittest: DNA and the Ultimate Forensic Record of Evolution), and Ken Miller (Only a Theory) fall into this category.
2. The New View: Some books make the case for a new way of looking at evolution. I'll call it the "New View." Many of Stephen Jay Gould's books fall into this category (The Structure of Evolutionary Theory). He refers to it as extending the modern synthesis. Most of the "extension" is based on a pluralist, rather than an adaptationist approach but other modifications are important. Two recent books by Michael Lynch (Origins of Genome Architecture) and Eugene Koonin (The Logic of Chance: The Nature and Origin of Biological Evolution) fall into this category. It's a view that I share.
3. The Radical View: Some books advocate a more-or-less complete overthrow of the Modern Synthesis, replacing it with the author's pet theory. Examples are: Marc Kirschner, and John Gerhart (The Plausibility of Life: Resolving Darwin's Dilemma), James Shapiro (Evolution: A View from the 21st Century), Lynn Margulis and Dorion Sagan (Acquiring Genomes: A Theory Of the Origin Of Species), Massimo Pigliucci and Gerd B. Müllerand (editors) (Evolution - the Extended Synthesis), many others.

You might think that these three categories represent a progression from a traditional view of evolution to a "new" view and then on to a more radical view. But the funny thing is that the "radical" views usually skip over the intermediate stage and focus on the traditional view as their main target. In fact, the authors of the "radical" books seem to be largely unaware of the "new" view.

The development of the "new" and "radical" views represent parallel tracks, not sequential tracks.

It's easy to dismiss all criticism of the traditional view based on the silliness of most of the radicals. This is a mistake. Those who advocate the "new" view have some serious points and they deserve a hearing. What does this "new" view look like? Here are some excerpts from Koonin and Lynch.

According to the Modern Synthesis, the evolution of life is a process of active adaptation of populations to changing environments. We now realize that although such adaptation is undoubtedly an essential component of the evolutionary process, it is not quantitatively dominant. Although fully aware of the oversimplification inherent in any attempts at grand definitions, I submit this:

The evolution of life is a stochastic process based on historical contingency, substantially constrained by various requirements for the maintenance of basic biological organization, and modulated by adaptation.

Eugene Koonin

Contrary to popular belief, evolution is not driven by natural selection alone. Many aspects of evolutionary change are indeed facilitated by natural selection, but all populations are influenced by nonadaptive forces of mutation, recombination, and random genetic drift. These additional forces are not simple embellishments around a primary axis of selection, but are quite the opposite—they dictate what natural selection can and cannot do. Although this basic principle has been known for a long time, it is quite remarkable that most biologists continue to interpret nearly aspect of biodiversity as an outcome of adaptive processes. This blind acceptance of natural selection as the only force relevant to evolution has led to a lot of sloppy thinking, and is probably the primary reason why evolution is viewed as a soft science by much of society.

A central point to be explained in this book is that most aspects of evolution at the genome level cannot be fully explained in adaptive terms, and moreover, that many features could not have emerged without a near-complete disengagement of the power of natural selection. This contention is supported by a wide array of comparative data, as well as by well-established principles of population genetics. However, even if such support did not exist, there is an important reason for pursuing nonadaptive (neutral) models of evolution. If one wants to confidently invoke a specific adaptive scenario to explain an observed pattern of comparative data, then an ability to reject a hypothesis based entirely on the nonadaptive forces of evolution is critical.

Michael Lynch

When it comes to the acceptance of nonadaptive evolution, we've probably reached the middle stage of a multi-step process. Today, most evolutionary biologists will say, "Of course it's true, that's what I've believed all along. What's the problem?" Then tomorrow, or the next day, they'll write or say something that sounds very much like an adaptationist.

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