Science Sunday

ScienceSunday: Darwin Day!

Today, February 12, marks the 203th birthday of Charles Darwin. His landmark work, On the Origin of Species, revolutionized biology, and the scientific view of how the diversity of life that exists today came into being, by proposing the idea that, according to common legend, Thomas Henry Huxley, a contemporary of Darwin’s, first read it, he asked how he didn’t see it first, it seemed so clear and obvious. This idea was that of evolution by natural selection

Darwin's original Tree of Life

Natural selection is an elegantly simple idea: All populations have some amount of variation in them. Most of these differences are neutral; some are harmful; other provide an advantage in the current environment. Neutral variations come and go over generations. Harmful variations die out. Beneficial variations become more common. Over time, based on the selective pressures of the environment, these variations add up, causing significant changes and eventually fundamentally changing a species. This is one of the primary mechanisms by which both microevolution (changes within a species) and macroevolution (change into a new species) occur.  However, there are other mechanisms of evolution as well, such as sexual selection and genetic drift. Artificial selection also occurs, when humans use the principles of selection and genetics to adapt a species to their own purposes. We do this with crops, to produce more nutritious and filling food, and with domestic animals (such as all the different breeds of dogs), both for aesthetic and practical purposes. In fact, artificial selection of pigeons, along with the observation of different species of finches on the Galapagos islands, provided the impetus for Origin.

While there have been some modifications to Darwin’s theory of natural selection, as scientists came to understand how heredity works, after the works of Gregor Mendel were rediscovered and reevaluated, and learned more about ecology and modes of evolution, by and large the theory has remained the same, even 153 years after The Origin of Species was published. Natural selection is one of the most well-supported theories in science, with independent lines of evidence supporting it from nearly every branch of biology – ecology, paleontology, medicine, genetics, and more.

If you’re interested in reading Darwin’s works, including On the Origin of Species and The Descent of Man, they are available as open source documents at Darwin Online.

Images from Wikipedia

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Ali Marie

Ali Marie

Ali Marie is a recent Master's of Education graduate, and is now venturing back into the world of non-traditional education, as an outreach program leader at a children's museum. Her interests vary widely, but include board games, music, dinosaurs, and science as a whole.

You can find Ali on Twitter, @ascientifica.

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