Ever since Darwin first published his theory of evolution in On the Origin of Species by Means of Natural Selection there has been ongoing controversy surrounding the theory and it's implications. It's important to note that this controversy does not exist within the scientific community, but in the realm of dogmatic religious thinking which requires the Biblical creation story to be literal history. For scientists, the theory provides the overarching framework by which all of biology is understood. Perhaps the most remarkable aspect of Darwin's theory is that while Darwin published it 150 years ago, before the age of genetics and biochemistry, it flourishes under intense critical scrutiny and continues to be supported by new scientific evidence that Darwin could never have conceived of. Due to it's exceptional simplicity and vast explanatory power, this theory has been called, 'the greatest idea ever' by Daniel Dennett. I too would add Darwin's idea to the short list of best ideas ever. In Evolution Carl Zimmer chronicles the history of this great idea, from its earliest days, to it's role in modern science, and into the future.Zimmer recounts the days prior to Darwin's theory in which the fact that life on earth had changed over time was well known among most people with a rudimentary knowledge of scientific discovery. Many thinkers who immediately preceded Darwin had put forth their own ideas about how such change took place. However they often came up woefully short in their ability to explain the scientific data and generate fruitful predictions about future findings. Darwin's unique contribution occurred to him while travelling the world as a young and green naturalist aboard the HMS Beagle. He realized that the apparent changes in life over time were in direct response to environmental changes brought on by geological and climatological events in the earth's history. As the environment changed, certain traits that varied among members of a species might confer ever so slight a survival advantage to the individual(s) possessing that trait. When extrapolated over immense periods of time and further environmental changes, such changes will lead to a great diversity of life such as we observe in our world. This mechanism for change, which Darwin called 'Natural Selection', is the defining characteristic of Darwinian evolution.
Throughout the book, as science marches forward, Zimmer provides numerous examples of findings that could only have been predicted under the framework of Darwinian evolution and thus lend further support for Darwin's theory. He also discusses the many anti-evolution objections and legal battles that have arisen over the years, most notably in the United States. Early objections often took the form of overtly religious sentiment, citing a literal interpretation of the Biblical creation story and genealogies as reason enough to reject Darwinian evolution as the explanation for life's diversity and the geological evidence for a very old earth. However, after a handful of high profile embarrassments showing that this form of young earth creationism had no scientific merit, the anti-evolutionists abandoned this form of overt religious objection.
More recently, anti-evolutionists have attempted to reframe their objections in scientific terminology, with concepts such as Intelligent Design (ID). While ID dresses itself up in scientific language, it lacks any scientific credibility since it doesn't adhere to the scientific method of generating and testing hypotheses, nor does it provide any evidence in support of it's 'theory'. While ID advocates like to pretend that their objections have some scientific basis rather than simply being religious arguments, they are incapable of supporting their conclusions with any form of scientific data. Not only is their objection motivated solely by their overly simplistic literal interpretation of scripture, ID promotes a way of thinking that is intellectually inert. The manner by which ID draws conclusions is by looking for gaps in our existing scientific understanding, such as how the human blood clotting mechanism evolved. Once such a gap is identified, ID then waves it's magic wand and concludes that an Intelligent Designer (read God) created the structure from scratch. This sort of premature conclusion serves only to stifle further investigation or understanding of the human blood clotting mechanism since it suggests that all is known that we are capable of knowing. This manner of thinking not only lacks scientific credibility, but also strains theological credulity as well. What happens to our conceptions of God if and when we do determine how the blood clotting mechanism evolved? Objections to evolution are not scientific, or even scientifically motivated. When someone suggests that science curriculum should 'teach the controversy' or 'the weaknesses of evolution', they are asking for equal time to be given for a severely inferior idea that has no scientific basis and they are not promoting quality science education.
Towards the end of the book, Zimmer spends a little bit of time discussing some of the more recent and perhaps speculative ideas that have sprouted from Darwinian thinking such as evolutionary psychology, cultural evolution, artificial intelligence, and ecology. His discussion of each of these is rather brief, but a good overview of some of the newer developments in fields that have been and will continue to be informed by Darwinian evolution. For each of these, there are much more comprehensive discussions to be found elsewhere, but Zimmer provides a good introduction.
For a relatively short book (423 pages) Evolution touches on a wide variety of subjects and scientific findings, with the purpose of demonstrating the importance and far reach of Darwin's theory. While the book may be a little bit overwhelming as an introduction to Evolution, it is a great second or third book for someone who has done a little bit of reading about evolution.
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