Antebellum Scientific Thought On Human Evolution
Antebellum scientific thought was dominated by theories of human evolution that attempted to create the image of racial groups as distinct units, isolated from one another, or as hailing from a single common ancestor, united under such a connection. The divergent nature of the arguments at the core of each theory caused great debate amongst scientists, but also indicated their sentiments towards slavery.
The dominant theory of polygenism, supported by Louis Agassiz and Samuel Morton, functioned as a scientific justification of slavery. Polygenism opposed the commonly held view that all of humankind were the descendants of Adam, as espoused in the Book of Genesis, in favor of the theory that humans of different races originated from fundamentally different ancestors. Polygenism thus viewed each race as a single unit discrete from others, and believed that the distinct physical qualities of each race were immutable and passed down from one generation to the next. American polygenism was fortified by the work of creationist Samuel Morton in his Crania Americana (1839) and Crania Aegyptica (1844) in which he studied the skulls of the five major races and identified variations in cranial capacity and facial features specific to each race. Morton concluded that each race possessed different levels of intellect and that the variations between each race’s skull were far too vast for them to all hail from a common ancestor, leading polygenists to believed that God, or a divine Creator, placed each race on Earth in order of their intelligence, with the large-headed ‘Caucasians’ first and smaller-headed ‘Negroes’ last.
European-born naturalist Louis Agassiz was polygenism’s foremost supporter in antebellum scientific thought. Agassiz held that that all living creatures were situated within a great chain of being given their personal degree of perfection in relation to the primordial ideal of their respective species. As the product of both Agassiz’s ordered view of the universe and the racialized hierarchy of Morton’s studied crania, polygenism emerged as a scientific justification of slavery. It upheld the social hierarchy of antebellum America; white people were positioned at the very top of the chain, dominant and biologically ‘perfect’, and black people at the bottom, biologically ‘inferior’.
As polygenism entered mainstream American thought, those who benefited from its scientific racism were able to legitimize their racism and justify their support for the oppression and horrible mistreatment of African slaves. Though some polygenists claimed to be anti-slavery, it is impossible to separate such claims from their support for an such explicitly racist concept.
Charles Lyell’s theory that long periods of time caused gradual changes in the Earth’s geologic surface influenced the work of Darwin and created opposition to catastrophism, thus paving the way for Darwin’s evolutionary theory to take hold. Herbert contends that the success of Darwin’s Origin of the Species relied on the geologic theories regarding the antiquity of the Earth and species extinction (2015). During the first half of the nineteenth century, myriad American scientists were supporters of catastrophism, a theory with roots in Christian theology and the devout conception of humankind as existing within close temporal proximity to Genesis.
Catastrophists held that God realized his divine plan for Earth by executing specific creations at different times; he destroyed life on Earth through a single great catastrophe (i.e. a great flood), and would then repopulate the planet with new species. Catastrophists understood changes in species and the earth’s geologic crust as a result of each catastrophe. Darwin’s theory of evolution was influenced greatly by Charles Lyell, a geologist who rose to prominence after offering an explanation of changes in the Earth’s geologic crust that challenged catastrophism.
In both Pompeii and Herculaneum, Lyell observed that destructive volcanic eruptions allowed for the gradual accretion of fresh soil. Similarly, his study of the Niagara Falls led him to conclude that the forceful water had caused the falls to erode 30cm a year. Lyell identified that the original Falls were two times the size he had seen them at in 1842 and 1852, respectively, and given his formula for erosion, concluded that it had taken them 35,000 years to reach their contemporary size.
Ultimately, Lyell held that such changes were consequences of the gradually cumulative effects of natural forces over long spans of time. Lyell’s conception of time as something slow and immeasurable validated Charles Darwin’s theory of evolution, as an extended period of time uninterrupted by great catastrophes was necessary to his process of natural selection. Twenty-nine years after the 1930 release of Principles of Geology, a work that showcased Lyell’s gradual-change theory, Darwin would publish his own groundbreaking text – one strongly influenced by Lyell’s geological work.
Darwin’s study of variations within species of animals and plants led to the development of his own theory of evolution, one which opposed polygenism. English naturalist Darwin published Origin of the Species on the eve of the American Civil War. In this seminal work, Darwin empirically studied different forms of natural life that he observed during his time on the Beagle and the period following his disembarkation of the ship. Darwin proposed that an increase in the population of a specific species would cause the individuals with characteristics poorly suited to their environment to die off, thus allowing those with advantageous traits to survive and pass their traits down to the next generation. Through this process of natural selection, a species would evolve from their common primordial ancestor (and potentially create new species, or in the case of humankind, new races.
At the heart of Darwin’s text exists the theory of common descent, or the monogenic theory of human evolution: that every race within each species had their origins in a common ancestor. Though he infamously skirted around the explicit mention of humankind in Origin, Darwin’s theory of evolution affirmed that every human race shared a common ancestor, and thus all races were equal. Darwin’s empirically-testable theory of evolution negated the legitimacy of polygeny and thus its justification of slavery. The theory’s abolitionist undercurrent was no mistake; it was well known that Darwin’s worldview was founded on the attainment of moral progress and the abolishment of slavery.
Conclusion
Antebellum scientific thought on human evolution was fundamentally characterized by dichotomous theories that on the one hand attempted to prove the superiority of Caucasians over non-white races, and on the other attempted to prove the unity and equality of all races. As the American Civil War drew to a close and slavery was abolished, the pseudo-scientific racism at the heart of polygenism displaced the theory from favor in mainstream science. In turn, Darwin’s empirically-testable theory of evolution via natural selection and common descent inspired a major paradigm shift away from racism and towards the progress of humanity.
