What does Howie believe to be the four reasons why it is good for brain cells to die in the book, The Mezzanine: A Novel?

• The brain undergoes a pruning to improve processing capacity.

• The best neurons survive human bad habits like drinking, making the brain stronger as a whole.

• Surviving neurons make imitation possible.

• Neuron death is necessary to deepen and increase the subtlety of one's ideas.