The animal kingdom contains a wide range of animals that could be considered “persons”, which we are learning as scientists stop imposing human assumptions and instead learn how they interact in their own environment. As a consequence, we are realizing that we have grossly underestimated both the scope and the scale of animal intelligence.[1] Evolution would be inexplicably discontinuous if only humans, or only mammals, or only vertebrates were self-aware.[2] One of the measures of intelligence used is the mirror test for self-recognition, and elephants, chimpanzees, dolphins,[3] and magpies all passed with flying colors.
More important, though, than simple self-recognition is what is referred to as being the subject-of-a-life.[4] Does the entity have a sense of continuity over time, of engagement in a life process? If the answer is “yes,” then harm would limit or cut short those future possibilities. A corollary of that sense of having one’s own perspective is metacognition (thinking about thinking), which research has demonstrated occurs in at least cetaceans[5] and chimpanzees.[6]
Much of the focus of research has been in the arena of intelligence, decision-making, and problem solving, and there is now ample evidence that elephants and cetaceans (whales and dolphins) in particular are very intelligent, second only to humans. Indeed, research is demonstrating that a growing range of vertebrates could be considered nonhuman persons:
- Cetaceans: Whales and dolphins
- Elephants
- Great apes and other primates
- Bears
- Birds
- Other vertebrate species
- Invertebrates
[1] C. Siebert, “Animals Like Us,” Popular Science (January 2015): 52-55.
[2] J. Dunayer, “The Rights of Sentient Beings: Moving Beyond Old and New Speciesism,” in The Politics of Species: Reshaping Our Relationships with Other Animals, ed. R. Corbey & A. Lanjouw, 27-39 (Cambridge: Cambridge University Press, 2013).
[3] D. Reiss & L. Marino, “Mirror Self-Recognition in the Bottlenose Dolphin: A Case of Cognitive Convergence,” PNAS 98 (2001): 5937-5942.
[4] T. Regan, The Case for Animal Rights (Berkeley: University of California Press, 1983).
[5] L. Marino, R.C. Connor, R.E. Fordyce, L.M. Herman, P.R. Hof, L. Lefebvre, D. Lusseau, B. McCowan, E.A. Nimchinsky, A.A. Pack, L. Rendell, J.S. Reidenberg, D. Reiss, M.D. Uhen, E. Van der Gucht, & H. Whitehead, “Cetaceans Have Complex Brains for Complex Cognition,” PLoS: Biology 5, no. 5 (2007).
[6] M.J. Beran, J.D. Smith, & B.M. Perdu, “Language-Trained Chimpanzees (Pan Troglodytes) Name What They Have Seen But Look First at What They Have Not Seen,” Psychological Science 24, no. 5 (2013): 660-666.
