There is an important biologic backstory to Michael Lundblad's ambitious new book, which examines the consequences within US literature and culture, circa 1900, of the idea that people are animals too.
Here is the backstory: in or about 1800, the possibility emerged for thinking of human beings as part of, rather than outside, the animal kingdom. The Great Chain of Being from classical philosophy had once organized all entities, supernatural and natural, along an ideal vertical scale. But the new, naturalistic taxonomies of the nineteenth century used a different figure, the Tree of Life, to describe the relationship among living creatures. This new model linked all species, human and nonhuman, in terms of descent—and the tree itself could change over time, with branches extending, diverging, even breaking off.
Here is how Erasmus Darwin in Zoonomia (1794–96) described the naturalistic way of placing beings “endued with animality” in relation...