To the ancients, soul was anima, that which animates, the living-, moving-, breathing-ness of a biological being. In this sense, not only animals but plants have souls (of different capacities appropriate to what they are). For many religions, by contrast, the soul is specifically incorporeal, perhaps immortal, and believed to be unique to human beings, who are responsible (to a point) for its condition. To modern science it is, if anything, the hard problem of consciousness, also commonly thought to be the province of just one species.
~ Caitrin Nicol