The most sophisticated form of cell death, however, is unlike the other two types. Apoptosis, a Greek word used to describe falling leaves, is a programmed form of cell death. When a cell becomes old or disrepair sets in, it is nudged, usually by signaling molecules, to undergo a form of controlled self-demolition. Unlike in necrosis, the cell doesn’t burst, doesn’t tax the immune system, but quietly dissolves. Apoptosis is the reason our bone marrow doesn’t weigh two tons or our intestines don’t grow indefinitely.

As important as apoptosis is to death, it is essential for life. While as humans, we often consciously or unconsciously hope to achieve immortality, immortality has a very real existence in the cellular world — it’s called cancer. In fact, most cancers occur because of defects in apoptosis, and most novel cancer therapies are designed to allow cell death to occur as it normally would.

In many ways, therefore, life and death at a cellular level are much more socially conscious than how we interface with these phenomena at a human level. For cells, what is good for the organism is best for the cell. Even though cells are designed entirely to survive, an appropriate death is central to the survival of the organism, which itself has to die in a similar fashion for the sake of the society and ecosystem it inhabits.

We humans spend much of our lives denying death. Death, however, is not the enemy. If there is an enemy, it is the fear that death arouses. The fear of death often induces us to make choices that defy the biological constraints of our existence. Such choices often lead us to a fate that more closely resembles necrosis, involving the futile activation of innumerable resources eventually resulting in a cataclysmic outcome, rather than apoptosis. Furthermore, even as we hope to defy our mortality, our cells show the devastation that can occur for the organism if even one cell among billions achieves immortality.

When I asked Robert Horvitz, the Nobel Prize-winning biologist at the Massachusetts Institute of Technology who was part of the group that discovered apoptosis, what lessons we could learn from cell death, his answer demonstrated exactly why we have failed to understand death in the context of our lives: “Only once before has someone approached me to discuss the existential questions that might relate what is known about cell death to human existence.”

The question for us, then, is: What is the human equivalent of apoptosis in the context of our society? One way to approach that question is to look at what the human equivalent of necrosis is. To me, if a human being is in the hospital with intensive, life-sustaining therapies such as artificial respiration, nutrition or dialysis sustaining them with little hope of recovering reasonable brain function, such a state could be considered necrosis. Almost any other alternative, whether one dies in the hospital having rescinded resuscitation or intubation (DNR/DNI), at home with hospice services or with the aid of a physician’s prescription, has much more in common with apoptosis.