Theories of evolution

Linnaeus
In the mid-1700's, the Swedish biologist Carl Linnaeus developed the scientific nomenclature system still used in biology. He placed humans in the order of the Primates along with apes and monkeys, but seems to have encountered little criticism. Linnaeus' system was purely descriptive, making no claims about origins. Also, its hierarchical nature meshed well with the hierarchical social and political systems of the time.
Lamarck
The French scientist Jean Lamarck postulated in the late 1790's that organisms underwent changes in their lifetimes that were passed along to their offspring. Lamarck's celebrated example is the giraffe, which supposedly had to stretch to reach the leaves of trees and passed the tendency for a long neck on to its offspring. However, as anyone knows who has ever seen videos of Africa, the giraffe overshot the target because it grazes the trees from the top down. Actually, numerous experiments have failed to show any transmission of inherited characteristics. If Lamarck's mechanism existed, Eskimos ought by now to be able to live in the Arctic without clothing. In reality, Eskimos can freeze to death just like anyone else. Also, virtually nobody lives permanently above 5000 meters elevation; the human body just can't adapt to that little oxygen.
Nevertheless, Lamarck deserves credit for one important insight: organisms evolve to fit their environment. Lamarck seems to have encountered little criticism for making this suggestion.
Hutton and Lyell
At about the same time, James Hutton and other founders of geology were first working out the methods for interpreting the record in the rocks, and concluded that the Earth had to be far older than indicated by the Biblical account. In the 1830's Charles Lyell published his concept of uniformitarianism, the present is key to the past. Other geologists laid out the presently-used geological period names in their proper sequence, though they had no means of estimating the length of geologic time. There was some grumbling from Biblical literalists, but nothing approaching the fury that greeted evolution.
Darwin
During the 1830's, Charles Darwin made his celebrated voyage on the H.M.S. Beagle. And thereby hangs an interesting tale. Why was Darwin on the Beagle? The standard answer is that Darwin was the ship's naturalist. But British naval doctrine of the day called for the ship's physician to be responsible for gathering scientific observations.
British naval discipline was very rigid; seamen did not socialize with officers, junior officers did not socialize with senior officers, and nobody socialized with the captain. On a long voyage the captain could go insane from isolation. One option sometimes was to bring his family along so they could all go crazy together. (Just imagine being cooped up with several children in a room ten feet square on a rolling ship for several months at a time.) The captain of the Beagle, Fitzroy, had reason to be concerned since depression ran in his family and some of his relatives had committed suicide. (Fitzroy himself would about 30 years later.) So another solution was found: take along a civilian, of the appropriate social class but not bound by naval regulations. Darwin was hired aboard as an extra naturalist, or "supernumerary", but his real job was social peer and gentleman companion to the captain.
The plan didn't work very well. The regular naturalist was a capable man but was no Darwin, and he had himself sent home for medical reasons from Brazil. Fitzroy was a Biblical literalist and social conservative; Darwin much more liberal, and poor Fitzroy found himself almost as isolated as if he'd gone by himself. Nevertheless, the voyage gave Darwin ample time to make observations You can map the voyage of the Beagle by simply scanning a world atlas for place names containing "Darwin", "Beagle" and "Fitzroy", commemorating places where the Beagle stopped.
It's easy to cast Fitzroy as a villain here; he really isn't. He was a Biblical literalist not so much for doctrinal reasons than because he believed it was the best system for maintaining social order and good naval discipline. Later in his life he battled courageously for a system of weather forecasting to help reduce shipwrecks around the British Isles. He was capable of fighting for scientific innovation and was concerned about saving human life. He appears to have been a thoroughly decent if somewhat rigid man. But for the rest of his life he and Darwin had a love-hate relationship and Fitzroy was deeply chagrined at his own unwitting role in the discovery of evolution.Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay