In The Fruit, the Tree, and the Serpent: Why We See So Well, anthropologist Lynn Isbell makes the case that humans evolved distinctive capabilities to see and to communicate, in response to snakes, the most dangerous predator of our primate ancestors. The book marshalls evidence across a range of disciplines: neuroscience, primate behavior, paleogeography, molecular biology, and genetics to make the argument.
Isbell’s argument sounds like “Eve’s revenge” against the argument in Terrence Deacon’s Symbolic Species. While Isbell argues that “the snake did it”, the Deacon argues that “Adam did it” – humans’s understanding of symbols evolved to express the sexual ownership of women by men. In his book, Harvard neurologist and anthropologist argues that the understanding of symbols is the main differentiator of human intelligence. Humans invented an abstract symbol and group ritual – such as wedding rings and marriage cermonies – to mark the fact that a woman is the exclusive sexual property of a man. This allowed humans to live co-operatively in groups (which enables more efficient hunting and gathering).
Both stories are fascinating assemblages of scientific evidence making arguments about the origins of distinctively human capabilities. But, as I said in a blog post about the Symbolic Species, Deacon’s argument skips over alternative explanations of the same evidence. The ability to see beyond immediate evidence to consequences remote in time and space can be explained with Robin Dunbar’s hypothesis of gossip, or storytelling in general. Deacon himself argues that language is overdetermined; there are so many advantages that it’s hard to tell what came first.
I enjoyed Deacon’s book for the evidence it brought about how the human brain processes language, and I look forward to reading Isbell’s book, which I read about in the Atlantic review, for the research she assembles about the evolution of vision and cognitive capabilities. But I strongly suspect that I’ll think about Isbell’s argument what I thought about Deacon’s – there is evidence for it, but there are also many other ways to explain the path of evolution, and no solid way to prove these explanations of the distant past. We’re humans, so we search for causes and tell origin myths, even when we’re using the tools of science.