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Carolus Linnaeus
Created a system to classify different organisms by their similarities and relationships by evolution. He also proposed that organisms are different by Hybridization: a crossing by different species (a group of organisms closely related enough to produce fertile offspring). (Influenced Georges-Louis LeClerc de Buffon) -
Georges-Louis LeClerc de Buffon
Suggested that different species shared common ancestors. Buffon also argued that the Earth was older than 6,000 years old (influenced Charles Lyell) -
James Hutton
Proposed that the changes he saw in different landforms caused slow changed to occur over a long amount of time. Hutton had to argue with other scientists that it wasn't a short amount of time causing those changes, but a long amount of time. Created the principle of Gradualism: when soil, sand, or dirt over a long period of time would create something as big as rivers, canyons, or mountains. (Influenced George Cuvier, Charles Lyell, and Charles Darwin) -
Thomas Malthus
In 1789, Malthus wrote and published a book called "The Principle of Population". He wrote observations and explained how if the human race wasn't kept under control at a certain level, the world would become overpopulated. Malthus also described how starvation and world hunger would always be a problem, due to the human population increasing faster than the supply of food. (Influenced Alfred Russel Wallace and Charles Darwin) -
Erasmus Darwin
Between 1794 and 1796, Erasmus Darwin proposed that all living organisms were the offspring of a common ancestor. Along with this he also suggested that more-complex organisms would be the offspring of the less-complex organisms. (Influenced Charles Darwin) -
Jean-Baptiste Lamarck
Between 1744 - 1829, first proposed that organisms would always evolve to perfection, since no scientist believed organisms would go extinct. Lamarck took back his first proposal, then proposed that changes in an environment cause the organism to change which would lead to the use or disuse of an organ for the organism, over a long period of time. Those changes would be passed from one organism down to the other through reproduction. (Influenced Charles Darwin, Charles Lyell, and George Cuvier) -
George Cuvier
Cuvier didn't believe a species/organisms could go through evolution as the past scientists had, but he did believe that a species/organisms could go extinct. He examined rocks and discovered fossils, the remnants of organisms that lived in the past. Cuvier proved his theory by Catastrophism: when volcanoes, floods or earthquakes (Catastrophic events) would occur, they would wipe out past species/organisms causing them to become extinct. (Influenced Charles Lyell and Charles Darwin) -
Charles Lyell
He published "Principles of Geography" in the 1830s and grew James Hutton's theory of Gradualism. From the theory of Gradualism, Lyell created Uniformitarianism: the process that shape Earth's land was done together through time. He also observed that every layer of rock was formed together (uniform) and laid down by sand, rocks, or dirt. Uniformitarianism combined his theory and Gradualism, which replaced Catastrophism by George Cuvier. (Influenced Charles Darwin and Alfred Russel Wallace) -
Alfred Russel Wallace
Wallace and Charles Darwin decided to work together on the theory of natural selection. Both scientists had worked with animals and plants, which led them to present their theory to a group of scientists. Their theory stated 4 important key parts: Variation (the inherited differences in every organism), Overproduction (the competition between offspring to live), Adaptation (the better fit in an environment will live), and Descent with Modification (the best trait will be passed down). -
Charles Darwin (Continued)
Later on Darwin's voyage, he traveled up a mountain in the Andes and found the fossils from past marine organisms. An earthquake came and moved land up above sea-level, which Charles Darwin personally witnessed. His observations from the earthquake and marine fossils in the Andes Mountains solidified and supported Lyell's theory of Uniformitarianism. (Influenced Earnest Haeckel) -
Charles Darwin
Darwin traveled to the Galapagos in 1831 where he studied the Galapagos Tortoise and the Galapagos Finches. He observed how all the species on the island looked different from the same species on different islands, especially the tortoise. Those differences were the tortoise's diets, shell, skin, body, and living place. Darwin then came to the conclusion of Adaptation: a feature that allows an organism to become a better fit for its environment. -
Ernst Haeckel
He was influenced by one of Charles Darwin's books, "On The Origin of Species by Means of Natural Selection". This encouraged Haeckel to creat the Biogenetic Law which is also the Theory of Development: all species on Earth have a common ancestor. He found evidence from embryology which supported his theory of Development and the Biogenetic Law. -
E.J. Steele
Made a hypothesis that would give information to help explain Lamarckian Evolution: as somatic cells (any cells that are not the sexual-reproductive cells. ie skin cells, nerve cells, blood cells) change over time due to changes in their environment, copies of the mRNA (messenger RNA) that were produced become picked up by dormant retroviruses. The mRNA becomes mixed with the DNA by reverse transcription and inherited into the next generation of that organism.