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Jean Lamarck
In 1800 Lamarck first set forth the revolutionary notion of species mutability during a lecture to students in his invertebrate zoology class at the National Museum of Natural History. By 1802 the general outlines of his broad theory of organic transformation had taken shape. -
George Cuvier
In 1825, the French naturalist Georges Cuvier proposed his theory of catastrophes that states fossils show that animal and plant species are destroyed time and again by deluges and other natural cataclysms and that new species evolve only after that. -
Charles Lyell
In 1838, Lyell published the first volume of Elements of Geology, describing European shells, rocks and fossils. Lyell was a religious man and didn't believe in evolution until later, after he read On the Origin of the Species. After that, he accepted it as a possibility, seen in his later 1863 publication of The Geological Evidence of the Antiquity of Man and his 1865 revisions of Principles of Geology. -
Charles Darwin
In The Origin of Species, published in 1859, he laid out the evidence demonstrating the evolution of organisms. -
Alfred Wallace
In 1889, Wallace wrote the book Darwinism, which explained and defended natural selection. In it, he proposed the hypothesis that natural selection could drive the reproductive isolation of two varieties by encouraging the development of barriers against hybridisation. -
Stephen Gould
Gould's most significant contribution to evolutionary biology was the theory of punctuated equilibrium developed with Niles Eldredge in 1972. The theory proposes that most evolution is characterized by long periods of evolutionary stability, infrequently punctuated by swift periods of branching speciation.