Man and embryo: Historicizing ideas about humanity in the study of reproduction, 18th–19th centuries

This article is concerned with historicizing the idea that all people belong to a single collective of biological human beings. It analyzes implications and changes in the concept of “Man” over the 18th and 19th centuries, particularly in the study of reproduction and embryos. Examining gendered assumptions in 18th-century generation systems shows how these theories described the formation of male more than female embryos. This asymmetry matched the idea that only rational males, standing above nature, were determinant for the concept of Man. In the 19th century, new studies pushed Man closer to the rest of the natural world, provoking a readjustment in definitions of Man and understandings of the human embryo. However, far from equalizing humanity, the 19th-century concept of Man introduced a hierarchy in the human species based on different levels of embryonic and evolutionary development.