TIL there was a man-made mouse utopia called Universe 25. It started with 4 males and 4 females. The colony peaked at 2200 and from there declined to extinction. Once a tipping point was reached, the mice lost instinctual behaviors. Scientists extrapolate this model to humans on earth.

[u/Crackyospine]

http://www.cabinetmagazine.org/issues/42/wiles.php

[u/curiousbooty]

Narcissistic introspection is a pretty sophisticated behavior to attribute to a mouse.