However, Darwin did believe that animals had some sense of self, and also championed the notion of evolutionary continuity, leading him to also write, "Nevertheless, the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind." Thus, there are shades of gray and not black-and-white differences between humans and other animals in
cognitive abilities. So, while animals might not ponder life and death the way humans do, they still may have some sense of self.
After decades of studying animals ranging from coyotes and
gray wolves to domestic dogs and Adelie penguins and other birds, I've come to the conclusion that not only are some animals self-aware, but also that there are degrees of self-awareness. Combined with studies by my colleagues, it's wholly plausible to suggest that many animals have a sense of "mine-ness" or "body-ness." So, for example, when an experimental treatment, an object, or another animal affects an individual, he or she experiences that "something is happening to this body."
Many primates relax when being groomed and individuals of many species actively seek pleasure and avoid pain. There's no need to associate "this body" with "my body" or with "me" (or "I"). Many animals also know the placement in space of parts of their body as they run, jump, perform acrobatics, or move as a coordinated hunting unit or flock without running into one another. They know their body isn't someone else's body.
