2009 has been colder than normal here in Emmitsburg's corner of the universe, which put a stop to any ambitions I might have had for observing nature first-hand. I seem to have reached that time of life when a cold, brisk day
prompts me to curl up in a comfortable chair with a good book instead of bundling up and going outside to look for birds. In theory, this should be acceptable; there is a vast amount of scientific information I have yet to master, as well as music to hear and novels to enjoy, and the birds will be happy for me to look at them
when it is warmer. In practice, though, it hasn't worked well. The chair does not cooperate. We have grown old together, and it has conformed itself to the exact shape of my rheumatic joints, so I seldom last 15 minutes in it without dozing off. Nevertheless, we keep trying.
Between naps, I have been thinking a lot about Charles Darwin. It would be hard for a biologist not to think of him; February 12 was his 200th birthday, and the news media have been full of articles and programs about him, most of which contained errors. Hoping for something more original, I looked up
Darwin's horoscope for Feb. 12, and found the following: "You are whimsical and funny and don't mind showing a silly side… but when it comes to serious business you have the sang-froid of a ninja master." Not too good a fit! The only silly thing I ever heard of Darwin doing was when traveling through Argentina with some local
gauchos as guides, he tried to catch a cow with a weighted rope or bola (the gaucho version of a lasso); he got the rope tangled around his horse's legs and had a nasty fall. I had to look up sang-froid; it comes from a French word meaning cold-blooded, and now means composure or imperturbability. That doesn't fit either; Darwin
suffered from stress and depression all his life. So I decided to stick to what I know.
I can't claim to be an expert on Darwin, but it is impossible to be an ecologist without having some knowledge of his "theory." All of the things we know in science begin as theories, which are nothing more than attempts to explain how and why things work. Some theories are about specific details; for
example, in the 1620's William Harvey published a theory that the circulation of blood was caused by the pumping of the heart. This was a radical idea because it disagreed with the teaching of famous doctors like Galen, but it was tested by experiment and quickly proved to be correct. In Darwin's case, the questions before him
were on a grander scale, like why fossils exist, or why animals like the cat family occur in such varied forms as lions, tigers, leopards and cheetahs. People had become increasingly curious about such questions in Darwin's time, because digging canals and coal mines in the Industrial Revolution had led to the discovery of
fossils that were unlike living animals, and botanical gardens and zoos were full of strange creatures that had been unknown in Europe before the time of Columbus. The idea that living things might change over the course of time was not new; several people had proposed theories of evolution before Darwin's time, but none of them
could be defended successfully.
Darwin's theory was deceptively simple; it began with two obvious points. First was variation, the fact that all individuals are different. If you buy a herd of sheep, they all look alike at first, but within a week you will have names for all of them. Some have different amounts of black around their
faces; some are bigger, or more aggressive, or tamer, or better mothers, but each is different. Point two was over-production: every species produces more offspring than can ever survive. This is self-evident: Think what the world would be like if every maple seed grew into a mature tree, or every mouse lived to produce full
litters, all of which survived and reproduced. From these two points Darwin reasoned that if all individuals are different and the environment cannot support all of them, the ones that are best suited to the environment will have a better chance of surviving… i.e., survival of the fittest. And if the environment changed over
long periods of time, survival of the fittest would make living things change too. This all made sense; the sticking point was that in order for change to be permanent, the characteristics that enabled the fittest to survive would have to be inherited, and when Darwin first figured this out, no one understood how inheritance
worked. He knew this was a weakness in his theory, and was reluctant to publish it until he had overwhelming evidence; so he worked on it for 20 years before circumstances finally forced him to publish in 1859.
When Darwin's theory first came out, many biologists questioned it because of the problem about heredity; others accepted it at once, assuming that heredity eventually would be worked out. They were right; at just that time, Gregor Mendel was doing experiments with peas which would lead to the birth of
the new science of Genetics. Mendel published his work in 1865 and sent a copy to Darwin. Unfortunately, it was written in German, which Darwin could read only with difficulty; he did not have time to sit down and translate it, so he laid it aside and it was found among his papers after he died. It is one of the great ironies in
history that when other scientists criticized Darwin's theory, the answer to their criticism was lying there on his desk, unread. Of course, Darwin might not have understood Mendel's paper even if he had read it; several other well-known scholars read it and failed to see its relevance to evolution. So the connection between
evolution and genetics was not fully worked out until the 1930s, long after both Darwin and Mendel had died.
The economist, Martin Feldstein, once remarked that "knowing" is always a matter of degree. This means scientists have the ultimate job security; their task is to understand nature, and they are aware that they can never know it all. New questions arise; new theories attempt to explain them. If they fail,
they are discarded; if they hold up, eventually they become accepted as correct explanations of the natural world. They are then called paradigms, and become part of the mindset of scientists; they are assumed to be true unless something is discovered that they cannot explain, and then a new theory must be developed. Scientists
are human; like everyone else, they do not like to give up their old ideas, so it takes time for a new theory to be accepted. This process of replacing a major old idea with a new one is called a paradigm shift. Young people usually accept the new idea first, and it may take years of argument and controversy before it gains
acceptance by everyone else. David Brooks observed that "intellectual history moves forward in a hearse;" some people hang onto old ideas as long as they live, even if they were proved wrong years ago.
Darwin's theory initiated the greatest paradigm shift in the history of biology; in public opinion it is still not complete. Recent surveys show that evolution is now accepted by over 99.5 % of all biologists, but public acceptance has been much slower. Various surveys have found that 150 years after its
publication, between 39 and 51% of non-scientists believe in evolution. This is roughly the same fraction of the public as those who believe in horoscopes. In the meanwhile, it is worth noting that Abraham Lincoln, who was born on the same day as Darwin, also generated a paradigm shift: 143 years after the Civil War ended, the
American electorate decided that a person's competence and ability were more important than the color of his skin. Paradigm shifts may be slow, but they do happen.
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