The different legal status of human being and animals is a consequence of their different ontological status. Human being has dignity, which requires the recognition of rights that ensure a dignified life. The animal lacks dignity, but it must be protected by law, even though it does not have recognized rights. This study focuses on the ontological main differences between human being and animals, differences that nowadays can be tested empirically by the data provided by paleoanthropology. Human rights, based on dignity, are the guarantee that human being can develop exclusive capabilities to their way of being and that animals lack.