There are two things we should take away from this. First, self-awareness is not a hard and fast line. Instead, it is probably a continuum. That is an especially important lesson to keep in mind with animal research. A species might have the skill, even if some individuals do not. This is true for chimpanzees, who do not all pass the mark test, and can lose the ability as they age. Linked concepts, like empathy, exist in species and individuals that are not able to pass a mark test. Rats, for instance, do not pass the mark but still engage in some limited empathetic behaviors. And passing the test does not mean an individual has self-awareness, or mirrors, all figured out. After all, it is not uncommon to see a human child pass a mark test and then immediately look behind the mirror, as though not quite getting what it is.
Second, the mark test itself is not the end all and be all of self-awareness.
"Self-awareness is like gravity," Johns Hopkins's Roma says. "We can't touch it directly, so if we want to measure it, scientists must develop valid techniques to directly observe its effects. Currently, mirror mark tests are the best-known and most accepted method, but the absence of an effect does not necessarily mean the absence of the thing we're trying to measure. Ultimately, evidence from multiple techniques should converge on the truth, whatever it may be. Such is the beauty of how scientific advances turn controversy into common knowledge."