A “Scientific Fairy Tale” of Origin of Mammals

The ranking of living beings in a hierarchical order has persisted across different cultures and philosophies for millennia. Aristotle’s “ladder of life” and the mediaeval notion of the “great chain of being” categorised organisms into “higher” and “lower” forms. While a hierarchical view of the living world was dominant in biology until the nineteenth century, modern biological thinking attempts to avoid categorising extant organisms as “higher” and “lower” or “primitive” and “advanced”. However, in this paper, I show that the “ladder of life” persists in subtle ways. Critical discourse analysis of current biology textbooks shows a linear history of life, with the “Age of Amphibians” followed by the “Age of Reptiles” and then the “Age of Mammals”. Textbooks downplay episodes in evolutionary history that seemingly counter this linear history of life, such as the “dominance” of ancient relatives of mammals before the “Age of Reptiles”. I further argue that by terming the ancient relatives of mammals as proto-mammals but dinosaurs as reptiles (not “proto-reptiles”), the “origin” of mammals is delayed, and problematise this terminology. I argue that similar to the origin stories of nations or human groups, the “origin” of taxonomic groups can be powerful tools that give an appearance of purpose for their existence. The origin of mammals as nocturnal creatures during the “age of darkness” when “monstrous” reptiles were “dominating” gives the narrative moral and political undertones. In addition to implicitly justifying the “Age of Mammals”, this linear and hierarchical history of life limits understanding of the diversity and richness of life.