Darwin and his magnificent theory

Happy Birthday Darwin!

February 12, 2009 marks what would be Charles Darwin’s 200th birthday and the 150th anniversary of his landmark publication, On the Origin of Species. Lovers of science and those who acknowledge what an important discovery evolution is, will celebrate by having Darwin celebrations, lectures and discussions.

The reason Darwin is lauded as a genius may be a mystery to some, particularly to those who are fundamentally opposed to the theory of evolution. With that in mind, I will discuss a few reasons why science lovers and scientists will honour Darwin and his assertion that the tremendous variety of life is recorded in the natural world around us.

Evolution is the most well-supported and solid theory in the science canon. Even gravity, which is self-evident every time we get out of bed, does not boast such unified support. Russian-American geneticist Theodosius Dobzhansky even went as far to say that “Nothing in Biology makes sense except in the light of evolution”. Put simply, evolution is the unified theory of biology.

Before moving on with a thorough treatment of why evolution and Darwin are celebrated it is worth mentioning what Darwin presented in On the Origin of Species 150 years ago. Darwin outlined his observations of the natural world and therefore evidence that populations modify and adapt to environmental pressures. He called the mechanism that gives rise to new adaptations and species “Natural Selection”. Here is a snippet from On the Origin of Species that sums up his theory nicely:

As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form.

This pattern of inheritance, adaptation and selection was later coined “Survival of the Fittest” though Darwin himself never actually coined the phrase. In todays terms, evolution is defined as a change in gene frequency over time. Darwin only had a simple, vastly incomplete fossil record and observations from his time in the Galapagos archipelago. It would take more than 70 years after Darwin’s death in 1882 for a more complete picture of how evolution occurs in the cells of organisms. It was James Watson and Francis Crick who discovered the DNA helix and the genetic revolution began, confirming the observations made by Darwin and his contemporaries.

Since Darwin’s account entered the scientific arena it has successfully withstood an immense amount of testing from multiple lines of inquiry. Today there exists a massive amount of evidence with a more complete picture of how evolution works. Genetics, geology, molecular studies, biochemical and anatomical findings converge to show evolution to be a fact and natural selection (among other drivers) as a mechanism for evolutionary change. The fossil record now contains a wealth of species and a tree of evolutionary change emerges from this data. As we dig deeper, the fossils become less complex until there are no vertebrate species – showing that vertebrate species emerged during the Cambrian Explosion 530 million years ago.

Geneticists can now map the entire genome of species showing how species are related on a genetic level. For instance, the human genome is approximately 98% identical to that of chimpanzees. More specifically, mutations in genes provide unambiguous clues to inheritance. A great example can be seen in the fact that humans cannot synthesise vitamin C. Unlike many other mammals we need to consume vitamin C in our diet, which isn’t a problem given the amount of oranges we produce! The gene for the synthesis of vitamin C exists within humans but is “faulty”. Our primate ancestors, who also cannot synthesise vitamin C have the exact same gene with the exact same mutation that gives rise to it not working.

When one really grasps the power and elegance of evolution and what it says about how life developed, it is as startling and as astonishing as looking at another galaxy through a high powered telescope.

I have run out of space here to fully explain how and why evolution is probably, as Richard Dawkins would say, “the most powerful idea to ever occur to a human mind”. Hence forth, I shall return to this fascinating topic soon.


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