Were he biblical in his longevity, Charles Darwin would be 200 years old today. This year is also the 150th anniversary of his groundbreaking “Origin of Species”. I was listening to a Podcast of NPR’s “All Things Considered” the other day about the controversy still surrounding Darwin in the U.S. – a program which prompted much rolling of eyes from your underwhelming correspondent. I guess after spending four plus years in places where Darwin is about as controversial as Galileo, one tires of hearing about the ongoing attempt to discredit his ideas in theocratic Islamic states. Oh, and the U.S. as well.

In the days and months preceding Darwin’s bicentennial year, there has been a lot of revisionist history surrounding the naturalist – rewriting him either as a buffoon, anti-christ or saint – none of which is particularly relevant. There has also been a recent conceit in the popular science press to question the validity of Darwin’s theory based on recent molecular evidence regarding the ‘Tree of Life’ (an artificial construct in itself). This is a dangerous meme, because publications like The New Scientist are not suggesting that Darwin’s core hypotheses were wrong, they’re pointing out minor inconsistencies in the way that evolutionary biologists look at species level relationships. However, they have inadvertantly given fuel to the bonfire by which the Creationist fringe warms its hands.

So, in celebration of Darwin’s big 2-0-0, I thought it may be worth pausing to reflect on the elegantly simple, but earth shattering, ideas that Darwin first proposed 150 years ago.  

Darwin actually trained at Cambridge to become an Anglican minister, but was distracted by the opportunity to take a trip on the H.M.S. Beagle, which had been commissioned to survey South America for the Empire. Darwin, employed as the ship’s naturalist, departed Britain in December of 1831 and during the five year round the world journey of the Beagle collected vast geographical and biological samples. Later, back in England, he used some of these samples as a catalyst to the formation of a theory that he called transmutation. Poring over a collection of finches that he had made on the Galapagos Islands, he noticed that birds from different islands were similar both to each other and finches from the mainland. It occurred to Darwin that the islands could have been colonized by the mainland birds and then changed once they were established on the island. 

Not a particularly controversial idea, one would have thought, but the accepted dogma regarding the diversity of life on earth at the time was that each species had been created in its current manifestation – that a creator god had placed different species of finches on the continent of South America and on each island of the Galapagos about 3,000 years before. Darwin’s idea, the idea of descent with modification – that one species could have evolved from another, flew in the face of 1,800 years of church doctrine. It was nothing short of heresy. 

From this idea of transmutation, Darwin came up with the concept of natural selection – the idea that this transmutation was driven by ecological processes.  For this, he employed the theories of Thomas Malthus who proposed that human populations would eventually outgrow their food production capacity and kill themselves off. Darwin could see that if animal populations grew too large then they would be faced with a competitive situation and that individuals that were better able to cope with shortage would reproduce preferentially. Again, his finches served as inspiration. He noticed that different populations from different islands with different food sources had notably different beak shapes. Bed on that observation and he hypothesized that a random change in beak shape in one individual could give that bird an advantage in feeding. That bird would be more robust and thus would breed preferentially, passing that mutated beak shape to its progeny. Over a number of generations, the trait (beak shape) that lent a selective advantage would become fixed in the population. Hence natural selection driving speciation. Darwin expanded this idea by invoking examples of artificial selection in agriculture and animal husbandry. He continually invoked variation as the fuel that drove evolution. 

With both the idea of descent with modification and natural selection in hand, Darwin was able to construct the first evolutionary tree. Working with the idea of descent with modification, he was able to make the next intellectual hop to propose that similar species were related by a common ancestor. Again, in the context of our knowledge today it doesn’t sound like a vast leap, but Darwin’s contemporaries – the few who had accepted that there was any kind of transition of form – thought that it occured in a linear fashion. In other words, species A gave rise to species A’. Darwin’s breakthrough was the idea that species A gave rise to two new species – B and C. In his later book, “The Descent of Man”, he used the example of men being related to apes via a common ancestor – a proposal that threw the religious zealots of his day (and ours) into fits.*

Darwin’s ‘Origin of Species’ was by no means complete, a fact that Creationists take great joy in pointing out. He had no concept of the gene. Mendel was a contemporary, but they were not aware of one another’s work so Darwin was never able to fully explain the inheritance of variation. In his day, Darwin’s theories were just that – theoretical. It has taken 130 years of hard work by scientists to help those theories evolve into the fundamental scientific truth as we understand it today. And there are exceptions to some of Darwin’s hypotheses – there has been a lot of work recently into the role of horizontal gene transfer in speciation. The effects of epigenetic gene regulation have inspired some to reconsider Lamarck’s inconsistent ideas ideas about linear progressive evolution. Darwin was not infallible nor were all of his ideas completely original, but he was remarkably prescient for his time and an outstanding scientist. His ideas have stood the test of time and have been repeatedly supported by overwhelming experimental evidence. For that, he deserves respect from both the scientific and lay communities. For his ideas and his ability to synthesize a thesis that changed scientific though from natural observations, he stands among the great scientists and thinkers in our species’ history. 

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* To be strictly accurate, Darwin was not the first to propose that humans are related to apes, but he tends to get the credit.

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