Death

In humans and in A.s.a. H. pain is an important feedback signal, part of our value system. Forgetting is important for learning and death is forgetting taking place at a high level in the memory hierarchy.* Nick Lane argues that death is one of evolution's 10 greatest inventions.**
I've considered the question of immortality in various blogs.*** I had thought that we humans spent too much time in training and too little time working in our "prime." (15 Oct. 2010 blog) But perhaps if we come to live longer we will simply find ourselves attacking even tougher problems and will then have to spend proportionately more time in our "training" phase.

*e.g.,  "Science advances one funeral at a time."
** Life Ascending, Norton, 2009
***15 October 2010, 31 March 2018, 2 and 5 April 2018, and 16 March 2019 for example.