Many people point to an animal’s ability to recognize itself in the mirror as evidence that it is self aware.

However, a human conception of oneself takes five major forms of information outlined in Table 1. Each of these abilities can exist in gradations. For example:

both chimpanzees and human beings possess the ability to think about themselves into the future (i.e. an extended self-ability), but the computational power of the human extended self is far greater than that of the chimp, thereby allowing human adults to imagine themselves further into the future than chimpanzees can. Similarly, although early humans may have been able to reflect on their private experiences, modern human beings can think about the private aspects of themselves in abstract, symbolic ways.

Source (quote and table): The Evolution of the Human Self: Tracing the Natural History of Self-Awareness by Mark Leary and Nicole Buttermore