Transcription
Humans have been trying to figure out where they fit in the grand scheme of life on Earth for millennia. Today we know that we are a highly intelligent, bipedal ape which was honed over the course of over 7 million years in the East African Rift Valley, but this was not always the case.
During the Classical Period of Ancient Greece, Plato placed humans near the top of his Scala Naturae, a “Chain of Being” he devised for organizing things in a hierarchical fashion. The bottom place was held by inanimate objects and “lower” animals, with gods crowning the scale. Plato is said to once have given a speech that defined humans as “featherless bipeds”, to which fellow scholar Diogenes responded by bringing in a plucked chicken and proclaiming “Behold, a Man”. After this, “flat nails” were added to the criteria for being human. Plato’s student Aristotle expanded on this and noted that humans also have buttocks that act as a cushion when sitting.
Carl Linnaeus, who lived during the 1700s, is known as the father of taxonomy. He was a Creationist, as many were at the time, but when confronted with how to distinguish morphologically between humans and other apes, he is quoted as saying: “I demand of you, and of the whole world, that you show me a generic character—one that is according to generally accepted principles of classification, by which to distinguish between Man and Ape. I myself most assuredly know of none. ...But, if I had called man an ape, or vice versa, I should have fallen under the ban of all the ecclesiastics. It may be that as a naturalist I ought to have done so.” It should be evident that those who investigated where humans fall with regard to the rest of the animals, few could argue from empiricism that we were indeed apart from nature as something unique and not animal.
Charles Darwin took this to the next level. He is best known for his seminal work on the origins of biodiversity: On the Origin of Species, published in 1859. This text was informed by the voyage Darwin took around the world on the HMS Beagle, and is considered to be the foundation of evolutionary biology. For our purposes though, we must look to one of Darwin’s other most influential works: The Descent of Man, and Selection in Relation to Sex. In this text, published in 1871, Darwin turned his attention to his own species. He notes at the start: "The sole object of this work is to consider, firstly, whether man, like every other species, is descended from some pre-existing form; secondly, the manner of his development; and thirdly, the value of the differences between the so-called races of man."
Right off the bat Darwin notes homology links humans to other primates, mammals, and tetrapods, and that this link is present from the very beginning of development. Utilizing embryology, organisms were compared and shown to be quite similar. These similarities extended to the so-called “mental traits” as well. Darwin saw altruism and cleverness in other animals, from baboons to his own dog, and argued that modern civilization emerged from more ancient states. This was a far cry from the reigning idea that Western civilization was something of a created ideal, and deviations from it were a kind of fallen state of sociality. Ultimately, Darwin found human behaviors and supposed cognitive prowess to be but a stage upon a gradient, which linked humans with other animals: "Nevertheless the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind."
Descent also touched on the racial categorization of humans. Specifically, Darwin analyzes the proposed support for Polygenism and Monogenism. The former suggested that human races have different origins, whether created or evolved, while the latter that all human races come from a single common ancestor. It should come as no surprise that Polygenism was used by many to bolster ideas of racial superiority, namely that white Westerners were the dominant race. Darwin weighed the data, and found that monogenism was supported over polygenism primarily by the fact that all human races were interfertile, an observation originally made by John Bachman. This meant the abject rejection of the idea that human races were created separately or that they evolved from different ape ancestors, in favor of human unity through descent from a common ancestor.
This idea would find overwhelming support through genetic work, which we will discuss at length later in the series, but at the time genetics had not been established as a field. Genetics was developed by an obscure Augustinian friar far off in the Czech Republic in the year 1866. But this man’s work would not be rediscovered and appreciated until around 1900, after Darwin had already passed away. What must be appreciated is that while the foundational ideas of Biological Anthropology were first truly outlined by Darwin, humans had noticed their similarities with other animals for centuries. Genetics would provide the material for Darwin’s mechanisms of evolution, and would cement the continuity of the human species with the rest of the tree of life.