The great triumph (or horrible tragedy, depending on how you look at it) of being human is that our brains have evolved over hundreds of thousands of years to understand our mortality. We are, sadly, self-aware creatures. Even if we move through the day finding creative ways to deny our mortality, no matter how powerful, loved, or special we may feel, we know we are ultimately doomed to death and decay. This is a mental burden shared by precious few other species on Earth.