Evolution 101

Sunday, February 12, 2006

Darwin Day

I realize that I said this would be a weekly podcast, and it will, but I thought that this would be a good time to have a special episode since today is Charles Darwin’s birthday. Over the past couple years, more and more science enthusiasts have been celebrating today as “Darwin Day,” mostly just as a way to bring more attention to evolutionary theory in the context of the creation/evolution controversy in popular culture. This isn’t the only holiday of its kind- science enthusiasts have celebrated Isaac Newton’s birthday as Newtonmas, since his birthday is December 25th on the Julian calendar. When I was in high school, my chemistry teacher celebrated “Mole Day,” which honors the number of atoms in one mole of any substance, and I’ve heard that mathemtatics teachers celebrate Pi Day, which honors the number of the ratio between the circumference and radius of a circle. Creationists may use this day to accuse scientists of having a religious reverence for Darwin in the same way that Christians do for Jesus, Muslims do for Mohammed, and Buddhists do for the Buddha. To contradict this, I would like to point out one major difference- no scientist I have ever known has ever prayed to Darwin for a favorable result to an experiment.

But certainly Darwin has made an impact in popular culture, even in his own time. But a question posted to the messageboard by thoughtsurfer from Chicago seemed interesting to me. He says,

“A couple of years ago, my friend's wife looked at my Darwin fish on my car and said, "By the way, who's this Darwin guy?" I was pretty shocked by the question. I realize that most people won't know the fine details of most scientific theories, but to have never heard the name. I told her that was like not knowing who George Washington was.
Have there been any recent polls about how many Americans actually know what Darwinian theory is?”

That also seems shocking to me. But I went to religioustolerance.org, a great reference for religious statistics, and I was able to find a citation of a Gallup poll of Americans from 1991. Although this poll didn’t directly ask people if they knew who Charles Darwin was, it did as what beliefs they held in respect to creation and evolution. People were given three options: 1) strict creationism, 2) theistic evolution, which means that God directed the evolutionary process after creating basic organisms, and 3) naturalistic evolution, which omits any mention of the supernatural at all. The results showed that nearly half of all Americans believe in strict creationism, and less than ten percent believe in evolutionary theory as a naturalistic process. When the demographics were broken down, it showed that men were more likely to reject creationism than women, people with college educations were much more likely to reject creationism than people with only high school diplomas, and rejection of creationism increased directly with salary. Blacks were also more likely to accept creationism than whites. A similar poll in 1997 showed little change in these trends, but also compared laypeople to those with a science background. The results were pretty clear- 90% of people who’ve had some kind of science training rejected creationism outright, and over half accepted evolutionary theory as completely naturalistic.

This data helps motivate me to continue to engage in scientific outreach, such as this podcast. Although thoughtsurfer’s friend’s wife may have been less likely to accept evolution and, presumably, know about Charles Darwin as a woman, but she’d be even more likely to do so without any idea of the scientific principles and facts underlying it.

So who was Charles Darwin, anyway? Was he just some guy who thought up a crazy idea that just happened to be accepted as science and is advanced for the sole purpose of contradicting established religious beliefs? Hardly. Darwin was born on this day in 1809 in England to a wealthy doctor and member of the Unitarian church. (Incidentally, he shared his birthday with Abraham Lincoln, if that helps you place him in history) His paternal grandfather was Erasmus Darwin, who was a physician, inventor, and naturalist who theorized about evolution before his grandson was even born. Although his father wanted him to continue in the family tradition of medicine, Darwin was fascinated with science and biology at a very young age. Rejecting medicine, Darwin was enrolled in school to become an Anglican pastor and did very well as a theology student, but interrupted his education to continue his study of nature when he got the opportunity to travel on board a ship that was traveling to South America, called the Beagle. This journey took five years, and during this time Darwin spent most of his time observing different species and collecting fossils and specimens, as well as writing volumes of notes. He also spent time reading the work of geologist Charles Lyell, who had clearly shown that geological features such as rivers and canyons were the result of gradual changes caused by natural forces working slowly over time. It was particularly while visiting the Galapogos islands, which are a long chain of islands each separated from the other, and very far removed from the South American mainland, that Darwin made the observation that each island contained a slightly different species of finch. He wondered if each species could have derived originally from a single ancestor, which led to the idea of new species forming from existing populations. But this was not an idea that was unique to him- remember, his grandfather Erasmus Darwin had written about a very similar process, and Jean-Baptiste Lamarck, who I mentioned in the previous episode, had also theorized that species could change over time. What made Darwin’s idea unique was the mechanism that was proposed. In science, simply making an observation is not enough to warrant attention, nor is discussing the implications of those observations. For the scientific community to take notice, you have to provide a way to explain how those observations are taking place- you need a mechanism.

He got the inspiration for that mechanism from another man, Thomas Malthus. Malthus was a British political scientist and demographer who wrote wrote an essay demonstrating that, even by our best efforts, the human population would increase exponentially while the food supply would increase linearly. That is to say, the number of people would soon outnumber the availablility of food, and chaos would result. Darwin applied this principle to his idea of speciation- if a certain number of individuals in a population were competing for a limited food source, only those individuals who were best adapted to secure that food and reproduce would contribute offspring to the next generation. Eventually, those individuals that were poorly adapted to their environment would be bred out of existence, and only the best-adapted individuals would remain. Now, admittedly, this seems to be common sense to us now, but it was a revolutionary idea at the time. Darwin published his theory in 1859, calling it, ON the Origin of the Species by means of Natural Selection. Many people don’t know that Darwin wasn’t the only person to come up with this theory- a man named Alfred Russel Wallace, another naturalist working in Borneo had come up with the same idea independently.

Darwin published his theory reluctantly, because he knew that many people, especially those in religious circles, would object to it. But when he knew that Wallace had come to the same conclusions independently, he knew it was necessary to do so. If you get the chance to read Darwin directly, and I highly recommend that you try- you’ll find that Darwin is probably his own worst critic. I find this very commendable as a scientist- it’s a mark of scientific integrity to note the weaknesses of one’s explanation and the alternative explanations for one’s observations. Certainly Darwin’s theory was not complete- it was based on evidence, but he didn’t have nearly as much as he would have like. Fortunately, the discovery of countless fossils since his death and the burgeoning field of paleontology have provided and incredible amount of evidence in support of his theory. Another weakness of Darwin’s theory was that there was no proposed mechanism for the inheritance of traits. The work of Gregeor Mendel, which was carried out during Darwin’s lifetime but laid undiscovered until the early 20th century, showed that traits were inherited in discrete units, called genes. Further work showed that these genes were carried within cells’ deoxyribonucleic acid, or DNA, and Watson and Crick demonstrated the structure of DNA, leading to the modern field of molecular biology.

So, although Darwin’s work was important to the progress of science, I want to make it clear that there was nothing special about the man himself that led to his theory- he was doing nothing more than synthesizing existing science with new theories. If he hadn’t been born, we’d likely be discussing Wallace’s theory of natural selection instead. I also want to make it clear that evolutionary theory does not begin and end with Darwin. As I hope I’ve shown, the work of countless other scientists led up to his work, as well as have developed his work in the years past his death.

But regardless, happy 197th birthday, Charles, and thanks for all your hard work.

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