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Carolus Linnaeus
Linnaeus developed a classification system that was used to group organisms by their similarities. He deserted the idea that organisms did not change and suggested that some might have arisen through hybridization. -
Georges-Louis Leclerc de Buffon
He dismissed the idea that organisms arose separately and suggested that species shared ancestors. Linnaeus’s idea that organisms might have arisen through hybridization helped Buffon form these proposals. He also believed that the Earth was more than 6,000 years old. -
James Hutton
Hutton proposed the theory of gradualism which is the idea that the Earth’s land forms were shaped extremely slowly by many geological forces. -
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Erasmus Darwin
E. Darwin proposed that all living things were descended from a common ancestor. Buffons’s idea that species shared ancestors helped E. Darwin form this proposal. He also suggested that more-complex forms of life arose from less-complex forms of life. -
Thomas Malthus
He published “The Principle of Population” and talked about how the human race is likely to overpopulate causing space and food to become scarce. His book had concepts that reflected on the idea of struggle in natural selection. -
Jean-Baptiste Lamarck
He proposed that all organisms evolved toward perfection and complexity. He believed that species did not go extinct but instead evolved into other organisms. He came up with the idea known as the inheritance of acquired characteristics that stated environmental changes were causing an organism’s behavior and structure to change and evolve over long periods of time. -
Jean-Baptiste Lamarck (continued)
He made an incorrect conclusion about how traits were passed on. He thought traits in individual animals arose in direct response to environmental changes. -
George Cuvier
He didn’t think species could change and believe species could go extinct. He observed rock layers and fossils and saw that fossils in the deepest layers were different from upper layers. He came up with the theory of catastrophism which states that natural disasters such as floods and volcanic eruptions have happened often during Earth's long history, which shaped land forms and caused species to become extinct in the process. -
Charles Lyell
Lyell published the principles of Geology. He expanded Hutton’s theory of gradualism into the theory of uniformitarianism. Uniformitarianism states that the geologic processes that shape Earth are uniform through time. -
Alfred Russel Wallace
He co-developed the theory of evolution along with Darwin. He discovered the concept of evolution by natural selection on his eight year expedition to Indonesia where he observed all sorts of wildlife. Wallace and his mentor, Charles Darwin, published a joint paper since they had both come to the same conclusions. -
Charles Darwin
Darwin observed differences in appearance among island species. He saw that species found on one island looked different from those on the nearest mainland. Some differences seem suited to the animals' environments and diets and some did not. Darwin concluded that species may be able to adapt to their surroundings which lead to genetic change in a population over time. a common ancestor. -
Charles Darwin (continued part 1)
Next, Darwin observed fossil and geologic evidence supporting an ancient Earth and species changing over time on his voyage on the S.S. Beagle. Extended the ideas of an old Earth and slow, gradual change to the evolution of organisms and called this evolutionary gradualism. -
Charles Darwin (continued part 2)
He published a book called The Origin of Species explaining his findings: heritable differences, not all offspring can survive and reproduce, the struggle for existence, evolution by natural selection, and descent with modification from a common ancestor. -
Earnest Haeckel
He supported Darwin’s findings and in addition published the Recapitulation Theory. This theory states before organisms are born, they pass through developmental stages that resemble adult animals that come from another species, in nearly the same order that these other species split off during evolution. -
E.J. Steele
Steele hypothesized the RNA/reverse transcription-based mechanism of somatic hypermutation (cellular mechanism in the immune system and it adapts to foreign elements that come near). He combined ideas from both Darwin and Lamarck and formed what is now known as Meta-Lamarckism. Meta-Lamarckism combines their ideas and condenses it to gene activation by reverse transcription and natural selection.