Is death reversible? An experiment that partially revived slaughterhouse pig brains raises questions about the precise end point of life.
- Death has had a changing definition over the millennia. Originally, it meant cessation of breathing and a heart that had stopped.
- The advent of mechanical ventilators shifted the locus of death to the brain—dying became loss of brain function, an irreversible coma.
- Partial revival of pig brains hours after decapitation, which was demonstrated in a recent experiment, could again upend definitions of mortality.
“And death shall have no dominion”—Dylan Thomas, 1933
You will die, sooner or later. We all will. For everything that has a beginning has an end, an ineluctable consequence of the second law of thermodynamics.
Few of us like to think about this troubling fact. But once birthed, the thought of oblivion can’t be completely erased. It lurks in the unconscious shadows, ready to burst forth. In my case, it was only as a mature man that I became fully mortal. I had wasted an entire evening playing an addictive, first-person shooter video game—running through subterranean halls, flooded corridors, nightmarishly turning tunnels, and empty plazas under a foreign sun, firing my weapons at hordes of aliens relentlessly pursuing me. I went to bed, easily falling asleep but awoke abruptly a few hours later. Abstract knowledge had turned to felt reality—I was going to die! Not right there and then but eventually.
Evolution equipped our species with powerful defence mechanisms to deal with this foreknowledge—in particular, psychological suppression and religion. The former prevents us from consciously acknowledging or dwelling on such uncomfortable truths while the latter reassures us by promising never-ending life in a Christian heaven, an eternal cycle of Buddhist reincarnations or an uploading of our mind to the Cloud, the 21st-century equivalent of rapture for nerds.
Death has no such dominion over nonhuman animals. Although they can grieve for dead offspring and companions, there is no credible evidence that apes, dogs, crows and bees have minds sufficiently self-aware to be troubled by the insight that one day they will be no more. Thus, these defense mechanisms must have arisen in recent hominin evolution, in less than 10 million years.
Teachings from religious and philosophical traditions have long emphasized the opposite: look squarely into the hollow eyes of death to remove its sting. Daily meditation on nonbeing lessens its terror. As a scientist with intimations of my own mortality, my reflections turn toward understanding what death is.
Anyone who undertakes this quest will soon come to realize that death, this looming presence just over the horizon, is quite ill defined from both a scientific as well as a medical point of view.
FROM THE CHEST TO THE HEAD
Throughout history, everyone knew what death was. When somebody stopped breathing and his or her heart ceased beating for more than a few minutes, the person was, quite simply, dead. Death was a well-demarcated moment in time. All of this changed with the advent of mechanical ventilators and cardiac pacemakers in the middle of the 20th century. Modern high-tech intensive care decoupled the heart and the lungs from the brain that is responsible for mind, thought and action.
In response to these technological developments, in 1968, the famous Report of the Ad Hoc Committee of the Harvard Medical School introduced the concept of death as irreversible coma—that is, loss of brain function. This adjustment was given the force of law by the Uniform Determination of Death Act in 1981.
We investigate the question – is death reversible?
This document defines death as either irreversible cessation of circulatory and respiratory functions or irreversible halting of brain function. Quite simply, when your brain is dead, you are dead.