I don't know if it's true, but I once heard that the only degree Darwin possessed was in theology.
That is correct, but your question suggests you think that might somehow devalue his scientific work. Or perhaps you just found it surprising. A decade or so ago, on another forum, a member challenged the contribution of Darwin in large part because his degree was in theology. The following was my response. (The last two paragraphs addressed his additional argument that Wallace was more important than Darwin in the history of evolutionary theory.)
Creationists, pseudo scientists and others claiming a knowledge of and interest in evolution sometimes assert that Darwin was not educated as a scientist. Their implication is that, as a consequence, his theory of evolution by natural selection must be flawed. That foolish misapplication of logic is best ignored, leaving us to deal directly with the claim concerning his education.
1. The majority of naturalists in England in Darwin's time were ministers of the church. It was expected that one of the sons of any well to do family would acquire a living. These typically afforded much free time and these reverends indulged the Victorian interest in nature. (While Darwin's father intended he become a doctor, like himself and his brother, Darwin's distaste for the idea forced the alternative on him.)
2. From his childhood he was absorbed in nature. ("I was a born naturalist.") He collected specimens (wildlife collection was a Victorian passion) and avidly read nature books.
3. Darwin's degree may have been in theology, but while at Cambridge he was exposed to the logically constructed writing of Paley (
Natural Theology) and the penetrating logic of Whewell (
Bridgewater Treatises). He was also taught botany by Professor J. S. Henslow, who was a cleric, and geology by Adam Sedgwick, who was a cleric. Being a cleric was almost a requirement for being a naturalist at that time!
4. "Darwin's letters and biographical notes give the impression that in Cambridge he devoted more time to collecting beetles, discussing geology and botany with his professors and hunting and riding with similarly inclined friends, than to his prescribed studies." (Ernst Mayr, in
One Long Argument Harvard University Press 1991)
5. "..when Darwin had completed his Cambridge years he was an accomplished young naturalist." (ibid.)
6. He then embarked on the Beagle for a voyage lasting five years, where he was exposed to more opportunities for research than many a Ph.D. student, opportunities which he seized and made full use of, as evidenced by the specimens he collected, the learned reports he wrote, and the novel concepts he brought to geology and biology.
7. You rightly praise Wallace, but who was it in all of England, in the entire world, that Wallace chose to share his new hypothesis with? Who did he seek out as the one naturalist who could best evaluate its worth? Darwin. If Wallace was so enthused by Darwin, why are you so against him?
8. Wallace himself said this "[
Darwin's early works] great as each of them is separately, and, taken altogether, amazing as the production of one man, sink into insignificance as compared with the vast body of research and of thought of which the
Origin of Species is the brief epitome, and with which alone the name of Darwin is associated by the mass of educated men." (Natural Selection and Tropical Nature", London 1883.)