“For animals, as well as plants, there have never been individuals,” write Scott Gilbert, Jan Sapp and Alfred Tauber in The Quarterly Review of Biology — the 2012 paper, “A Symbiotic View of Life: We Have Never Been Individuals” (abstract, pdf):
Our aims in this overview are to: outline the data demonstrating that animals are symbiotic complexes of many species living together; demonstrate how a thoroughly symbiotic perspective opens important areas of research and offers fundamentally new conceptions of the organism; and explore what this new evidence means for biology, medicine, and for the conservation of biodiversity.
“Like all visible life forms, we are composites,” writes Dorion Sagan in the 2011 Society for Cultural Anthropology paper, “The Human is More than Human: Interspecies Communities and the New ‘Facts of Life'” (book, text, video):
Margaret McFall-Ngai … has proposed that the immune system evolved not to eliminate pathogens but to select for symbionts in the microbe-packed waters of our metazoan ancestors. The immune system in its origin may thus be more like an employment agency, recruiting desired species, than like a national security state, recognizing and refusing entry to guard the fake purity of the Self.
“We argue that interactions between animals and microbes are not specialized occurrences but rather are fundamentally important aspects of animal biology from development to systems ecology,” write McFall-Ngai and 25 coauthors in the 2013 Proceedings of the National Academy of Sciences paper, “Animals in a bacterial world, a new imperative for the life sciences” (abstract, pdf).
These papers describe what might be called the strong case for biodiversity. It’s not merely that species and functional diversity are critical to ecosystem processes. It’s that they are us. Other species are human kin. “The self,” as Tauber writes in the Stanford Encyclopedia of Philosophy, “is polymorphous and ill-defined.”