Originally published 13 November 2001
My first Social Security check arrived this week, a bittersweet milestone. On the one hand, it means a modest release from the pressure of making a living; more time to smell the roses, so to speak. On the other hand, the check will be a monthly reminder of…
Well, let’s not get morbid. With a little luck, my twilight years will be golden, and every one of those years is a gift of our scientific, relatively peaceable civilization.
Only a century ago, the average male lifetime in the United States was 45 years. Today it’s in the 70s — and rising. Never before in history have so many of us had the expectation of a ripe old age.
But the average lifetime won’t rise forever, at least not without some genetic jiggering. There are biological clocks ticking in every cell of our bodies. Our cells are fated one-by-one to die, each at its appointed time, until finally the entire colony of cells expires.
For multi-celled creatures like us, death is not the opposite of life; death is part of life.
Single-celled organisms are potentially immortal. With an appropriate environment and nutrients, bacteria can live forever. Genetically programmed, inevitable death appeared rather late in the history of life, just 600 million years ago, at the same time as sex and multicellularity. And it has only been in the last few decades that scientists have begun to understand that if you want to have creatures with eyes and ears, brains and backbones, gonads and gods, then you gotta have death, too.
Writing in the journal Nature, biologist Gerry Melino notes that an individual cell in a multicellular organism can do one of three things — divide, specialize, or commit suicide. If division and specialization occurred without cell suicide, an 80-year-old person would have 2 tons of bone marrow and a gut 16 kilometers, or 10 miles, long, Melino states.
The whole business of building and maintaining a multi-celled organism is a genetically orchestrated dance of cell division and cell death. For example, as a human embryo develops, the extremities of the limbs first look like stumpy ping-pong paddles. Then cells start to selectively die in a way that turns the paddles into hands and feet with digits. We have fingers and toes because certain cells were programmed for suicide.
So, death can be creative. The Grim Reaper has an alternate role as a Michelangelo who releases the form from within the block of marble.
Sooner or later, in every multi-celled creature, the reaping runs ahead of the shaping and we experience senescence, the physical decline of old age. Scientists are not sure how or why senescence evolved, but humans are the only creatures for which it makes much difference. For other animals and plants (and for ourselves until recently), death by accident or violence was a more likely fate than doddering old age. If evolution never selected against senescence, it may be because it never had a chance to do so.
But here I am living in a civilization that has invented antibiotics and childproof caps, vaccinations and seat belts, sterile parturition and the ABM Treaty. It is possible that I will collect my Social Security check for 10 or 20 years, unless I’m a victim of accident or fatal violence from my own species. This is a huge new thing in the history of life: Not nature red in tooth and claw, but Centrum Silver and senior aerobics.
For most of the history of our race, death came as a bolt from the blue — a snake bite, an impacted tooth, a thump on the head, starvation. There was an apparent arbitrariness to the circumstances, and our ancestors were quick to invoke the intervention of gods or malevolent spirits, and to imagine that the interruption was only temporary.
Now, with the benefit of medical science and the orderly assistance of civilized society, we live long enough to see that death is a necessary part of the plan, a corollary of life that is built into every cell of our bodies. This is all rather too new for us to have figured out how to deal with it. By and large, our cultural and religious responses to death are the products of a time when only the lucky survivor experienced senescence — when the Grim Reaper with his glistening scythe was a more continuous presence than the Michelangelo with his artful chisel.
Only a few thoughtful philosophers and scientists have been brave enough to consider the lessons of programmed cell death. Microbiologist Ursula Goodenough states this in her book, The Scared Depths of Nature: “Sex without death gets you single-celled algae and fungi…Death is the price paid to have trees and clams and birds and grasshoppers, and death is the price paid to have human consciousness, to be aware of all that shimmering awareness and all that love.”
Our bodily lives, she says, are the gifts wrought by our forthcoming deaths.
