Adaptation as a fact of life has been accepted by many of the great thinkers who have tackled the world of living organisms. It is their explanations of how adaptation arises that separates these thinkers. A few of the most significant ideas:[21]
Empedocles did not believe that adaptation required a final cause (~ purpose), but "came about naturally, since such things survived". Aristotle, however, did believe in final causes.
In natural theology, adaptation was interpreted as the work of a deity, even as evidence for the existence of God.[22] William Paley believed that organisms were perfectly adapted to the lives they lead, an argument that shadowed Leibniz, who had argued that God had brought about the best of all possible worlds. Voltaire's Dr Pangloss[23] is a parody of this optimistic idea, and Hume also argued against design.[24] The Bridgewater Treatises are a product of natural theology, though some of the authors managed to present their work in a fairly neutral manner. The series was lampooned by Robert Knox, who held quasi-evolutionary views, as the Bilgewater Treatises. Darwin broke with the tradition by emphasising the flaws and limitations which occurred in the animal and plant worlds.[25]
LamarckLamarck's is a proto-evolutionary theory of the inheritance of acquired traits, whose main purpose is to explain adaptations by natural means.[26] He proposed a tendency for organisms to become more complex, moving up a ladder of progress, plus "the influence of circumstances", usually expressed as use and disuse. His evolutionary ideas, and those of Geoffroy, fail because they cannot be reconciled with heredity. This was known even before Mendel by medical men interested in human races (Wells, Lawrence), and especially by Weismann.
Many other students of natural history, such as Buffon, accepted adaptation, and some also accepted evolution, without voicing their opinions as to the mechanism. This illustrates the real merit of Darwin and Wallace, and secondary figures such as Bates, for putting forward a mechanism whose significance had only been glimpsed previously. A century later, experimental field studies and breeding experiments by such as Ford and Dobzhansky produced evidence that natural selection was not only the 'engine' behind adaptation, but was a much stronger force than had previously been thought.[27][28][29]
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