Summary
Highlights
For millennia, humans have sought to understand their place in the natural world. Ancient Greek philosophers, like Plato, positioned humans high on his 'Scala Naturae' or 'Chain of Being'. Plato initially defined humans as 'featherless bipeds,' a definition humorously challenged by Diogenes, leading to the addition of 'flat nails' and Aristotle's observation of buttocks as a cushion for sitting. Historically, few empirical arguments could genuinely separate humans from the animal kingdom.
Carl Linnaeus, the father of taxonomy in the 1700s, struggled to morphologically distinguish humans from other apes. Despite being a Creationist, he acknowledged the lack of clear anatomical differences and humorously noted that, as a naturalist, he perhaps 'ought to have done so' had he not feared religious censure.
Charles Darwin's 'The Descent of Man, and Selection in Relation to Sex' (1871) directly addressed human origins. Darwin argued that humans, like all species, descended from pre-existing forms, highlighting homologies with other primates, mammals, and tetrapods evident from embryonic development. He also posited that human mental traits and behaviors, including altruism and cleverness, differed merely in degree, not in kind, from other animals, placing humanity on a continuum with the rest of the animal kingdom.
Darwin's 'Descent of Man' also tackled the debate between polygenism (human races having different origins) and monogenism (all human races originating from a single common ancestor). He found support for monogenism, primarily based on the interfertility of all human races, an observation made by John Bachman. This rejected ideas of racial superiority and separate creations or evolutions, advocating instead for the unity of humanity through common descent. This concept would later be overwhelmingly supported by genetic work.
While Darwin laid the foundational ideas for biological anthropology, cementing human continuity with the tree of life, genetics as a field was only developing around the same time. Gregor Mendel's work, conducted in 1866, was not rediscovered until around 1900, after Darwin's passing. This highlights that early biological anthropology, though recognizing human similarities with other animals for centuries, established its core principles before the full understanding of genetic mechanisms.