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On the Origin of Species | Context


Scientific Predecessors and Contemporaries

In contrast to some of the earlier characterizations of this period, it is clear the idea of evolution was not conceived in a vacuum. The ideas presented in On the Origin of Species build upon arguments proposed by previous and contemporary researchers who have tried to make similar issues clear. These sources of influence are clear upon reading On the Origin of Species, as Charles Darwin makes use of these ideas in presenting his own arguments for the theory of natural selection.

While often described as an opponent of Darwin's theory of natural selection, 18th-century French biologist Jean-Baptiste Lamarck was in fact one of the first naturalists to describe a theory of natural development in his work, Zoological Philosophy, in 1809. Lamarck's theory of inheritance of acquired characteristics argues a change in an organism during its life will pass directly to its offspring. While this accounts for inheritance-based change, it deviates fundamentally from Darwin's theory in it fails to account for the time span involved in these organismal changes. Furthermore, it only addresses change at the level of the individual, not the population.

Thomas Robert Malthus, an early-19th-century English economist, is also mentioned in On the Origin of Species thanks to his work on population growth in An Essay on the Principle of Population (1798). While Malthus's work focuses on human population growth, Darwin applies these ideas to other species as well. Darwin is particularly concerned with one of Malthus's ideas, known as the "Dismal theorem," which recognizes human population growth, when left unchecked, will outpace available subsistence resources. While Malthus uses this point to argue for human population control, Darwin argues natural selection includes a natural mechanism for population control of nonhuman organisms. This helps explain why some species survive while others fail.

Charles Lyell is another early-19th-century researcher who had a direct influence on Darwin's thinking. Lyell's major work, Principles of Geology, was published in three volumes over a period of three years, from 1830 to 1833. This groundbreaking work was premised on uniformitarianism—the idea the processes that shaped the earth for thousands of years are still the same processes shaping the earth today. Uniformitarianism went directly against the widely held belief the earth was shaped by cataclysmic events, such as volcanic eruptions. Not only did Principles of Geology provide evidence for the age of the earth, but it also provided a sense of the continuity of time that could be applied to species.

While Darwin was formulating his theory of natural selection, the botanist monk Gregor Mendel was conducting experiments on pea plants that would lead to discoveries on genetic heredity. Mendel lectured on his experiments in 1865 and published the paper "Experiments on Plant Hybrids" in the journal of the Natural Science Society in Brünn. His experiments led to what are now known as the law of segregation and law of independent assortment, both of which became the basis of modern genetic studies. While Darwin was unaware of Mendel's work at the time it was conducted, it provided a mechanism by which natural selection occurred. In the early 20th century, scientists and researchers combined Mendelian genetics and Darwin's theory of natural selection into what is now known as "the modern synthesis," or neo-Darwinism. In combination with later research, it was argued population-level changes were the result of natural selection, gene flow, mutations, and population drift. The modern synthesis continues to be the accepted theory today.

Early-19th-century naturalist and biologist Alfred Russel Wallace was one of Darwin's closest colleagues. While Wallace conceived an idea very similar to that of Darwin's theory of natural selection, he failed to receive the same public acclaim as Darwin. Having known of Darwin's work, Wallace sent the naturalist a letter detailing his idea. Darwin and Wallace would later give a joint presentation, but Darwin was the one to have their ideas published. Later in life, Wallace became a spiritualist, and became less convinced the idea of natural selection could account for everything.

HMS Beagle Expedition

Darwin departed from Plymouth, England, on December 27, 1831, aboard the HMS Beagle. The ship sailed around the tip of South America, to the Galápagos Islands, then to New Zealand, and finally to Cape Town, Africa, before heading back to England. All told, the trip lasted five years, ending in 1836. The data Darwin gathered on this journey informed his theory of natural selection.

The trip was initiated by a letter from one of Darwin's professors, John Stevens Henslow, detailing how Captain Robert FitzRoy was looking for a companion for a survey on the HMS Beagle. Darwin became FitzRoy's companion, as well as the ship's naturalist and geologist. During his voyages Darwin kept meticulous journals that would later bolster his theories. While the voyage sparked in Darwin the beginnings of his understanding of natural selection, it was not until he revisited his notes the many natural processes he observed would become clear.

Darwin was mainly concerned with understanding the geological processes he observed during the journey. This geological focus would help solidify his understanding of uniformitarianism, a process Darwin refers to over and over in On the Origin of Species in order to illustrate the theory of natural selection over a broad span of time.

During his time in South America, Darwin observed a variety of unique species, geological formations, and fossils that added to his ideas involving the history of unique structures (such as the blind tuco-tuco) and ancestral species (such as in the fossils of extinct armadillos).

From South America Darwin traveled to the location he is most associated with today, the Galápagos Islands. It is here he observed the variation in finch beak structure that led him to conclude years later they had adapted to different feeding methods. The latter portions of his journey to New Zealand reinforced his emphasis on Lyell's theory of uniformitarianism and provided experiences he would later draw on for his work On the Origin of Species.

Modern Influence

By the time of Darwin's death, the idea of evolution was fairly universally accepted. However, the specifics were still debated and under scrutiny. In contrast to the theory of natural selection, many were convinced evolution was working toward a particular purpose. Darwin's work provided the impetus for the end of the idea of rational design in scientific endeavors. This shift was not immediate, but occurred over many years. While creationism has remained a popular idea, this is only the case outside the scientific community.

Darwin's ideas have not remained static but have been reinterpreted and incorporated with new data. The first major incorporation was with Darwin and Mendel's work on genetic heredity. Even after the rediscovery of Mendel's experiments, many were not convinced Mendel's and Darwin's ideas were compatible. However, in 1942 Ernst Mayr and Julian Huxley published Systematics and the Origin of Species and Evolution: The Modern Synthesis, a work that attempted to translate genetic factors into testable field hypotheses.

Unfortunately, some racist ideas spawned from Darwin's theory, mainly social Darwinism—or the idea some human races were more "advanced" than others. This misconception would provide the rationalization for racial discrimination and imperialist policies during the 19th and 20th centuries. Despite the use of Darwin's name, social Darwinism has no connection to the theory of natural selection as described by Darwin himself. Rather, it is a misconception of his ideas applied to the common perception at the time that organism-level change was characterized by progression toward a specific ideal.

Today, Darwin is considered one of the most influential scientists because of his role in changing both the scientific and public perception of biological processes. Not only did he bring the concept of antiquity into the biological sciences, but he did so in a systematic way. His arguments were based on qualitative descriptions of field experiences that would pave the way for more quantitative descriptions. While today deductive methodology is argued to be the most useful for understanding scientific processes, Darwin's inductive methodology represents the first attempt to systematically describe the processes influencing biological variation.

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