What sort of thing, fundamentally, are you and I? For convenience, I use the term persimal to refer to the kind of thing we are, whatever that kind turns out to be. Accordingly, the question is, what are persimals? One possible answer is that persimalhood consists in being a human animal, but many theorists, including Derek Parfit and Jeff McMahan, not to mention John Locke, reject this idea in favor of a radically different view, according to which persimalhood consists in (...) having certain sorts of mental or psychological features. In this essay, I try to show that the animalist approach is defensible as against the mentalist approach. I also suggest that animalists have a plausible story to tell about cases such as brain transplantation and dicephaly that might appear to support the mentalist approach. (shrink)