Arkansas 180: A New World Revealed
“When on board H.M.S. Beagle, as naturalist, I was struck with certain facts in the distribution of the inhabitants of South America….” Thus begins Charles Darwin’s The Origin of Species By Means of Natural Selection, a book that has changed the way humans understand the world and our place in it.
William McComas: “Evolution has nothing to do with what the organisms might want. It has to do with what tools they have available and it has to do with what pressure is put on that population by nature itself.”
In 2009, people around the globe are celebrating the Year of Darwin: the 200th anniversary of the birth of Charles Darwin and the 150th anniversary of his landmark book.
William McComas, science education professor at the University of Arkansas, has visited the Galapagos Islands five times and has photographed the creatures that Darwin had observed.
William McComas: “By the time that Darwin got to the Galapagos Islands, he was at the end of his five year voyage. I think he had perhaps about…I think he had less than a year of travel left. So he’d been four years on the seas already and traveling extensively in South America. He’d visited other islands. He was a pattern-seeking guy and he was collecting data in a really interesting fashion. Trying hard, in some sense, not to jump to conclusions.”
It’s clear that many of the animals living on the Galapagos Islands did not originate there but carried the traits necessary to survive and for their progeny ultimately to evolve into new forms.
William McComas: “ At some point in the distant past, on rafts of vegetation washing off from the shore of South America, were these hapless tropical iguanas that got washed out to the Galapagos Islands. Evolution took these iguanas in two different directions. The iguanas evolved for life on land in one case — they’re called land iguanas — and the marine iguanas are the ones that developed this amazing ability to hold their breath for long periods of time in very cold water and feed on algae. The tortoises are as interesting a story and as clear a story about evolution as is told by the iguanas. Those that lived on the wet islands, they were able to feed on the ground. Their shell shape is very much like an Arkansas box tortoise — just a lot bigger. If the tortoises end up in a much more hostile environment, where food was harder to find on the ground, this is where evolution took the tortoises in two directions at the same time. They did become larger and at the same time they developed a very interesting phalanging on their shells. The reason that this was an advantage to the tortoise is that the food sources were higher up.”
Over the ten years after his return to England, Darwin considered what he had found, conferred with other scientists and in 1859 publishedOrigin of Species.
In his last sentence, he uses the word “evolved” for the first time in the book: “There is a grandeur in this view of life in which endless forms most beautiful and most wonderful have been, and are being, evolved.”
William F. McComas is the Parks Family Professor of Science and Technology Education in the College of Education and Health Professions at the University of Arkansas.