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Carolus Linnaeus
Carolus Linnaeus was a Swedish Botanist. He discovered and developed a system of classification for all organism known at the time. This system reflects evolutionary relationships and is still used to this day. He abandoned the common belief that organisms did not change and were fixed instead. He suggested that some may have come about through hybridization, crossing that could be observed through experiments with varieties of species. -
George-Louis LeClerc De Buffon
George-Louis LeClerc De Buffon rejected the belief that organisms arose separately and proposed that species shared ancestors based on evidence of past life on Earth. He alo rejected the idea that the Earth was only 6,000 years old and he thought it was much older. Another scientist, Charles Lyell, agreed with him on this -
James Hutton
James Hutton was a Scottish geologist who proposed the theory of gradualism. Gradualism id changed observed in landforms that slowly happened over a long period of time and that this was caused from slow processes that happened in the past. -
Erasmus Darwun
Erasmus Darwin was the grandfather of Charles Darwin and an English physician. Erasmus proposed that all living things were descended from a common ancestor and that more complex forms of life arose from less complex forms. -
Thomas Malthus
Malthus was an English cleric, scholar, and economist. In 1798, he published the Principle of Population, where he theorized that there would be overproduction if the population sizes were not regulated. He also said on top of that, population would increase at an exponential rate that the Earth would not have enough resources to provide for, which in the human race, could result in poverty and famine. This would result in competition between organisms to survive because of the little resources. -
Jean- Baptiste Lamarck
Lamarck proposed that all organisms evolved towards perfection and complexity. He did not think species went extinct and instead thought that they evolved into other organisms. He also proposed that environmental changes caused an organism's behavior to change. For example, he said that giraffe necks evolved as generations of them reached for leaves higher in the trees. -
George Cuvier
He did not think species could change but he did think they could become extinct. He observed fossils and found the ones in deeper layers differed from those closer to the surface. He also came up with the Theory of Catastrophism: natural disasters such as floods and volcanoes have frequently happened in Earth's history, shaping landforms and causing extinction of species in the process. The new species in each rock layer resulted from other ones moving into the area due to catastrophic events. -
Charles Lyell
Lyell expanded Hutton's theory of gradualism into the theory of uniformitarianism, which states that the geologic processes that shape the Earth are uniform through time. He observed processes that made small changes to the Earth's surface and inferred that changes similar had happened in the past. Uniformitarianism soon replaced catastrophism. He also influenced Charles Darwin. -
Alfred Russel Wallace
Wallace went in an 8 year expedition to the Dutch East Indies, now known as Indonesia. He collected over 100,000 specimens of animal, insect, and bird. He eventually came to the conclusion that all living things evolve by adapting to their environment. -
Charles Darwin
Charles Darwin, the grandson of Erasmus Darwin, was a British naturalist who came up with Darwinism, the modern theory of evolution. Darwinism states that all organisms develop through natural selection of inherited factors and adaptations that increase the individual's ability to survive and to reproduce. -
Ernst Haeckel
Haeckel studied evolution and animals. After reading Charles Darwin's published book, The Origin of Species, Haeckel proposed the biogenetic law. This theory states that evolutionary stages are repeated when a young animal is growing. -
E.J. Steele
E.J. Steele is an Australian molecular immunologist. He made a hypothesis that helped creating the first mechanism to prove John- Baptiste Lamarck's theory of Lamarckian evolution. When somatic cell changes occur because of environmental changes, copies of the new mRNA produced by the successful cells are collected by harmless viruses and are transported a to the germline. Then, the new genetic information is merged into DNA by a process involving reverse transcription.