EURASIAN MAGPIE VS GORILLA
In 1982, mirror tests on two, zoo-reared gorillas failed to demonstrate self-recognition. The authors wrote "[These studies]...suggest that the gorilla may be the only great ape which lacks the conceptual ability necessary for self-recognition." In 1993, a report was published that although six gorillas had previously failed to exhibit self-recognition.
The Eurasian magpie is the only bird to pass the mirror test. Researchers applied a small red, yellow or black sticker to the throat of five Eurasian magpies where they could be seen by the bird only by using a mirror. The birds were then given a mirror. The feel of the sticker on their throats did not seem to alarm the magpies, however, when the birds with colored stickers caught a glimpse of themselves in the mirror, they scratched at their throats - a clear indication that they recognized the image in the mirror as their own. Those that received a black sticker, invisible against the black neck feathers, did not react.
Birds lacks neocortex, the area where self-recognition was thought to reside. Then which part of the brain do birds like Magpies uses to process these complex cognition ? Why do Gorillas failed the mirror test ?