In the early 1600s, Rene Descartes developed mechanical philosophy, in which the universe was a sort of natural machine. There were others that followed him and indicated that all of the universe had developed without divine intervention. This was different from philosophers like Gottfried Leibniz and Johann Herder, who believed that evolution was a divine process. Pierre Maupertuis had a materialistic view of nature, indicating that reproduction created natural modifications that accrued over many generations to produce new species and new races of man. He was in support of natural selection and opposed taxonomists who felt that the qualities of species were unchanging. This idea of unchanging species was characteristic of natural theological thinking. In the late 1700s, theorists like James Burnett said that man probably developed from primates and that species evolved over time due to their overall responses to the environment. As mentioned, Erasmus Darwin was a part of this but said that a single living filament gave rise to all warm-blooded animals.
NINETEENTH CENTURY EVOLUTION The ideas and findings of paleontologists entered into evolutionary thinking by the early 19th century. George Cuvier looked at the structural differences between elephants of today, mastodons, and mammoths, which are extinct. He said they were distinct species and was the first to describe the probability that a species could become extinct. Fossils were increasingly looked at in rock layers, which helped to establish how old the earth was. Cuvier said that catastrophism in nature explained some extinction patterns. He also looked at fossil records to see how plant life has evolved. John Phillips, in 1841, identified three major eras in geology. These were the Paleozoic era, which involved the predominance of marine invertebrates, the Mesozoic era, which was predominated by reptiles, and the Cenozoic era, which was dominated by mammals. There was also the work of Adam Sedgwick and William Buckland, who also believed that catastrophic events led to mass extinction and the arrival of new species. Unlike more progressive theorists, researchers like William Buckland believed that the biblical flood was the last major catastrophe in terms of evolution and extinction. Charles Lyell, on the other hand, said that there were more gradual changes in geology that contributed to evolution rather than cataclysmic events.
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