“The price you pay for being aware of your own existence is having to confront the inevitability of your own individual demise.

Death awareness is the price we pay for self awareness.”

Professor Gordon Gallup, commenting on the fact that although chimpanzees are one of the few species that pass his ‘mirror’ self-awareness test, they begin to lose that ability when they pass the age of 30 — about 15 years before death.

[Source.]