Back in 2009, a Dartmouth neuroscientist named Craig Bennett was fed up with the increasingly
strong dogma surrounding studies of the human experience that used functional magnetic resonance imaging (fMRI). The public had grown to accept headlines that described the findings of recent studies: Men literally see women as objects, we're all actually racist and humans are hardwired for religion, altruism or monogamy. The studies themselves were increasingly designed to cultivate such headlines.
Bennett satirized these soft studies by putting a 3.5-pound salmon, a dead one, in an MRI machine and showing it pictures of humans with an array of facial expressions. With each, Bennett asked the dead fish what emotion it thought the photo showed. Bennett had a surprise in store. Functional scans found slight electrical activity in the fish's brain, which further demonstrated his point. "If I were a ridiculous researcher, I'd say, 'A dead salmon perceiving humans can tell their emotional state,'" he told Wired magazine.
His study (though mostly unnoticed) also underscored a larger issue facing the world right now. We have at our disposal technology that can detect the most profoundly minute signals of life. And yet, we have not yet reached the point where we can bring those signals back to any kind of meaningful level of consciousness once they've disappeared. We are still, in the second decade of the 21st century, unable to revive dead things, human, salmon or otherwise.
Perhaps most hauntingly, these machines challenge our definition of death. We've reached this weird point in human history where we've created technology that has leapfrogged over our traditional methods of distinguishing life, like looking for signs of respiration and feeling for a pulse. We cannot be sure whether those signals are life and are helpless to do anything but observe them. But we can sustain them, and it is in this ability that we reach our current conundrum: We have no idea when death occurs.
This problem is a contemporary one. In centuries past, the problem of defining death was insignificant, aside from the fear of being buried alive, which still loomed large on the minds of those approaching death. George Washington instructed his body be laid out for two days before being entombed, just in case. Frederic Chopin asked to be fully cut open prior to being buried. Safety coffins, a subcategory of caskets appeared in the 17th to 19th centuries. These caskets were generally outfitted with a bell attached to a string hanging down to the deceased's hand or some other means of alerting the living topside that a premature burial had indeed taken place.
Death was death, and there was no real need to define when it took place.
Then two advances -- organ transplantation and life-sustaining technology -- converged in the middle of the 20th century to give us urgent reasons to come up with an acceptable definition of death. We could now artificially maintain the mechanisms of life -- respiration and heartbeat -- in a person whose brain no longer functioned, ostensibly until the person died of old age. But what purpose does it serve to maintain the life of a terminally unconscious patient, especially after it became possible to transfer that person's organs into another person who could put them to good use?
Since science is incapable of quantifying when death occurs, it turned to society for guidance. The 1970s saw a spate of piecemeal legislation, as states created their own definitions of death. Those that did emphasized brain death. In 1981, a council of medical ethicists convened by Jimmy Carter supported this idea of brain-centered death, and the remaining states followed suit.
There is yet no federal definition of death, and there are actually a couple of ways that death can legally take place today. Cardiopulmonary death -- the cessation of a spontaneous heartbeat -- remains an accepted definition of death, but quantifying the moment of death still remains elusive. In 1997, an Institutes of Medicine panel decided that five minutes after the cessation of heartbeat was the moment of death. This choice was arbitrary and sentimental, however. Worse, during this time, the heart is starved of oxygen, and what was a viable transplant organ five minutes earlier becomes useless.
The other organ of life, the brain, has also proved prickly as a means of determining death. The focus for brain death has long been the brain stem, which controls the most basic functions like breathing. Medical science established rigorous criteria for brain stem death. Patients who are subjected to these tests have ice water squirted into their ears, have a tube introduced in their esophagus to induce gagging and are twice taken off ventilators to determine apnea, among other tests.
The problem is, again, some people who are apparently dead can still show the most primitive signs of life. We arrived at the most recent incarnation of the question of death, something like: If your lungs are moving, does that really mean you're still alive?
Last year, the President's Council on Bioethics answered no. Death is now the end of engagement with the world around us. If widely adopted, this idea would end the ventilator debate. A human engaged in the act of breathing does so for survival, a human whose lungs rise and fall does so because of the pressure exerted by a machine. He is no longer engaged in the act of survival and is therefore dead.
This is a momentous move; the heritage of our collective fear of being buried alive has prompted us for decades to err on the side of caution, to prevent even the slightest possibility that those physicians who harvest organs are actually taking them from living people. This newest concept of brain death signals that we have reached the point where we are opting to no longer believe our eyes, but to put our faith instead in the idea that death is something we are not yet able to detect.