Why do human cells die off so quickly?

Human cells die for one of two reasons. They either suffer from some kind of environmental trauma that suddenly and accidentally leads to cell death, or they kill themselves in a planned, controlled process known as apoptosis. It turns out that the latter scenario is very important for healthy human development and life.

Apoptosis is the opposite of unplanned cell death: it is the carefully executed death of a specific cell, sometimes called “programmed cell death” or “cell assisted suicide.” This ability to die on command is encoded in the genome of humans and other organisms. Apoptosis is used to maintain the number of cells in the body at a certain specific level so that the body can change rapidly, for example, during embryonic development and destroy harmful cells.