Babies show signs of recognizing themselves in the mirror at about 15 to 18 months of age. But dolphins can recognize themselves even earlier—as young as 7 months old, according to a study recently published in PLOS One.
Self-recognition takes sophisticated cognitive processing and was once thought to be a uniquely human ability. But since the 1970s, great apes, elephants, dolphins, and magpies (yes, a crow) have shown the capacity to recognize themselves in a mirror.