Nineteenth Century Evolution

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.

Jean-Baptiste Lamarck studied the transmutation of species. He did not think there was a common ancestor but that there were simple forms of life that were still being spontaneously generated. He felt that there was some type of life force that caused species to be more complex with time. This was related to the great chain of being. Remember too that he thought that changes in a species adaptation to the environment during its lifetime were later inherited by the offspring.

The concept of transmutation of species was a more primitive explanation for evolution. It described the ways in which certain species transformed into other species. Certain idealists like Louis Agassiz and Richard Own believed that species of plants and animals had fixed characteristics that were both unchangeable and developed by the creator. They used embryological patterns of development could explain the relationships between the species. Each of these ideas made Charles Darwin more convinced that he needed proof and sound science to back his theories.

As you have learned too, there were many ideas that predated Charles Darwin s theories on natural selection. Darwin himself looked at selective breeding and the ideas put forth by others indicating that harsh environmental conditions led to weeding out of the weakest individuals in a population. When Darwin wrote on natural selection, he named those early theorists that had anticipated natural selection before it was somewhat more proven.

Also prior to Darwin was Patrick Matthew, who indicated that, if there was enough of an evolutionary change leading to a new species, the new species might not be able to reproduce with species it had evolved from. This is how he defined a new species. We will talk about Charles Darwin in a minute but suffice it to say, he did not believe in the fixity of species, writing secretly on the transmutation of species prior to his actual finished work on natural selection.

By the time of Darwin in the 1850s, it was a hot topic of debate as to whether or not species evolved. Darwin s work changed all that by indicating that evolution existed by new species diverging from existing species. Thomas Henry Huxley was an anatomist who was convinced by Darwin s work on the origin of species. He displaced the ideas of natural theology with naturalism, which did not involve theological ideas. Huxley used paleontology to help explain aspects of evolution, which included the idea that birds evolved from reptiles. This was proven by the discovery of Archaeopteryx in Europe as well as North American ancient birds that had teeth. The evolution of horses was also uncovered through paleontological records.