Tuesday, September 1, 2015

Classics Club 12: On the Origin of Species by Means of Natural Selection

This was the most challenging read from my Classics Club list to date, probably because of the extensive and exhaustive details Darwin provided and the slow, meticulous way in which he built up the case for his theory evolution by means of natural selection. Not surprising really, since he knew how controversial this book would be, but the amount of technical detail on subjects I was not especially interested in (pigeon breeding for instance) did make for a slow and sometimes tedious read.

Despite this I'm pleased I made the effort. It has long been on my TBR list, since his theory of evolution is arguably the most important idea underpinning modern biology. I wanted to read it for myself rather than rely on the interpretations, and misinterpretations, of others.

Darwin's theory incorporated several well known facts - plus a few inferences. Within any species there are variations and  many of these variations are heritable.  If all the offspring of any species survived, then its population would increase. Yet, generally speaking, over time populations remain roughly stable. Resources are limited and thus there is a struggle for survival. Those individuals who survive are those more suited to their environment. As they reproduce they pass on their genes to future generations. Over time this can change the make up of the population. An example from nineteenth century illustrates this nicely. Peppered moths come into two colour variations - dark and pale. The dark variation used to be rare. During the Industrial Revolution pollution increased markedly. Dark peppered moths benefited since they were essentially camouflaged while the pale moths stood out and were easier pickings for predators.  Thus the darker moths were more likely to survive and to reproduce that their pale counterparts. By the end of the nineteenth century virtually all peppered moths were dark. In this case a drop in pollution levels led to a drop in the proportion of dark moths. In other cases over time variations within a species accumulate to form a new species. The Galapagos finches are a good example of this.

I was impressed by the wide variety of examples which Darwin used to make his point. His love and understanding of all areas of the natural world shone through. I do wonder if modern scientists, often forced to concentrate in very narrow areas of specialisation, would be able to formulate a similar theory. Perhaps that is why virtually all scientific papers today have numerous co-authors.

It was hard for me to understand why this book caused such an uproar. While not every single detail or supposition that Darwin made has proven true, the sheer weight of evidence which Darwin provided and the careful way in which he slowly built his argument,  seemed convincing to me. Then again I live more than 150 years later, in a society not so dominated by a literal interpretation of the Bible and in which modern science, over time,  has found more and more evidence supporting Darwin's theory.

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