Charles Darwin, the Voyage of HMS Beagle, and the Development of Darwinism

In his youth, Charles Darwin (1809-1882) was an indifferent student but something of an amateur naturalist, botanist, and geologist. There is a (possibly apocryphal) story that he was once out looking to add to his insect collection and found first one beetle and then another that he had to have. With both fists occupied, he then spotted yet a third desirable specimen. He attempted to solve the dilemma by popping one beetle into his mouth, freeing up a hand to grab the third. But this beetle expressed its dislike for its new environment by emitting an obnoxious fluid, causing Darwin to cough and gag so violently that he lost all three beetles.

Although originally slated for the Anglican Church, he early realized that this was not a suitable career for him. Instead, he signed on to the crew of HMS Beagle as an unpaid naturalist for a circumnavigation of the globe that would take five years. As the ship made its way around the southern tip of South America, Darwin traveled extensively through the continent's interior, examining the fossil beds and collecting biological specimens. He was impressed by the constantly changing varieties of life he saw, but his experiences in the Galapagos Islands off the coast of Ecuador were even more impressive. He encountered his famous finches there. He recognized the differences between organisms seen on the islands (which were of recent volcanic origin) and the mainland, and the differences in organisms between the islands themselves.

Upon his return to the United Kingdom, Darwin encountered the writings of Thomas Malthus, the famous "prophet of doom" who believed that the human population was expanding too rapidly and that humans would shortly exhaust available food and living space. Darwin applied his ideas to the ways in which populations of organisms are kept in check. But he was in no immediate rush to publish. He deliberated for many years on his observations and theories. Finally he was spurred into action when he learned that Alfred Russell Wallace was about to publish almost identical ideas independently conceived. And so in 1859 his magnum opus appeared--On the Origin of Species. Darwin's major ideas were not based on experimentation but on observation linked to a conceptual framework or paradigm; technically this makes his "theory" a hypothesis.

Darwin's great ideas can be succinctly summarized as:

1. Species are not immutable. This contradicts the idea prevalent at the time Origin was published that species are fixed (immutable.)

2. "Descent with modification" can account for life's diversity, all living things having descended from a very small number of common ancestors.

3. Natural selection, vulgarly expressed as "the survival of the fittest." There is much more to this idea, as we will discover shortly.