Christa died of pancreatic cancer. It was not the easy death we all hope will be our lot, a soft fade of lights finishing with the final click of a switch. She wasted away physically until her bones were shrink-wrapped in skin. Rather than a single light switch, she was like an office tower that blacks out one floor at a time as cleaners toil toward the basement.
In her final weeks Christa lost her memories, starting with the most recent and working backwards. On one day I visited she could no longer recognise her daughter, a woman in her twenties. A few days later her husband, to whom she had been married 30-odd years, was also a stranger. She gravitated unerringly toward her oldest memories, singing songs from her childhood, then nursery rhymes; and then she burbled and squealed like a baby—devoid of language, arms flailing with the random motor function of a newborn.
I hovered at her bedside in the hospice during her final hours. By then, it seemed, Christa was an empty vessel, her mind having long since parted company with her body. In the absence of her will, which might have overridden an automatic survival instinct, her body drew on primordial reserves, fighting tenaciously for every breath.
Then, in the small hours, she drew a sharp rattling breath, head arched back, eyes wide open, mouth framing a silent, harrowing scream. The priest, who some hours earlier had administered the last rights, placed a hand over her eyes to close them, smoothing her brow and adjusting her head to soften that awful rictus. Family and friends who had gathered around the bed were silent, each privately working through the moment.
The priest mumbled something and we moved closer to one another, seeking comfort. Then, from the centre of our huddle, came a huge gasp: Christa’s frame shook, her eyes jerked open and, oblivious to our horror, she was breathing again, desperately clutching at the air with her lungs. An hour or so later this happened again, and then one further time, before she finally succumbed to death.
Jaws of life
As we shuffled off into what was left of the night, the thought hardly seemed controversial to me that throughout the ordeal I hadn’t really borne witness to the moment that Christa died. The woman I had come to know had clearly not been present in that final-curtain scene. A beautiful actor gasping out an important last message, then slumping dead in the arms of a comforter, is a grand movie fiction, allowing us to imagine that we will remain intact, undiminished and radiant, until the end. In stark contrast to this, the death I had witnessed had been an erosion, an undignified decay of a human into something more primal.
Before the invention of machines that could measure brain activity and monitor vital signs, we had to rely on crude measurements of life. With only outward indicators— breathing, blinking, pulse—to guide those present, death often seemed to occur in an instant. Alive then dead, a transition from one side of a threshold to the other: thus has death been portrayed on the stage and in celluloid, as a single event.
In reality, what we witness as the body slumps into apparent lifelessness is simply the cessation of vital activities: air exchange, a beating heart, motor function. Brain activity can, and does, persist for a time longer. Certain auditory and other sensory pathways can remain intact for several minutes beyond a sign-posted death. The brain selectively turns off expendable and energy-hungry operations in a last-ditch fight for survival. This process, triggered by systemic stress, is now recognised as a key feature of death, even in cases of severe trauma.
Christa’s body started shutting down non-vital systems, including some higher brain functions—diverting precious energy to core metabolism—weeks before her final breath. Her primary tumour had metastasised, sending strong signals that a crisis was looming. Having been given adequate warning, her body was able to prepare counter-measures, to the extent that she could even conjure a response when respiration had failed.
For many people, though, a sudden curtailment of oxygen to the brain, through trauma or cardiac arrest, is their first knowledge that death is approaching. Without medical intervention, any internal response to such a drastic circumstance is likely to fail. In these circumstances, sudden loss of mobility, respiration and pulse masks a storm of brain activity.
Humans are neurocentric, in the habit of identifying themselves intrinsically or even solely with their consciousness. At the departure of a self-aware mind, little value is bestowed on a carcass. Philosophers have long derided the body as the vehicle of the mind, and clerics have called it the vessel of the soul. When my mother died last year, a death that was similar in many ways to Christa’s, I surprised myself, finding that I could handle her corpse just a few minutes after her death with no feeling towards it. My emotions were tied up with her departed consciousness, essence, soul—call it what you will. My callousness toward her remains seemed incongruous to me even at the time, given that her body had given birth to me and nurtured me. Yet without animation this body meant little.
We don’t override mind-bias easily, and neither should we, yet humans are far more than conscious entities inhabiting a transportation system. Organs other than the brain are vital to our integrity. We are complex communities of cells interacting through chemical exchange. We are arrays of specialised organs and support systems, drug factories and electrical networks. We are storage banks, sensory pathways, webs of finely balanced defence mechanisms, regulation systems and elaborate self-repair units.
It is tempting to take the view that mind and body are unrelated or only tenuously related, but that dichotomy becomes less convincing as knowledge advances. Small changes in the balance of brain chemicals, such as neurotransmitters (e.g. dopamine or serotonin), in hormone levels, in signals transmitted through the nervous system, even in diet, can radically affect personality, mood and intelligence, the touchstones of self-perception. A brain reacts intimately to the ever-changing state of the body, and the body obeys the commands of the brain. The division of mind and body is less clear-cut than it might appear.
Death, too, not only shuts down the mind, but seeps through the body’s systems at every level—organism, organ, cell and sub-cell—and each system declines along an independent trajectory. Death should really be viewed as a cascade of little deaths culminating in a critical loss of viability rather than a single event.
Before the middle of the 20th century, death was ascertained by checking for a pulse. But as emergency medicine improved, cardiac arrest came to be viewed as merely the failure of one important support system to still-viable organs, a reversible step on a journey that leads to death only when intervention fails. Now, modern first aid steps up to a state of quasi-death—in which all the outward signs of death are present—knowing that the patient can be revived through the use of cardiopulmonary resuscitation (CPR) and defibrillation, often with little or no permanent damage.
Normally, the window for resuscitation—before organs suffer significant damage or the brain undergoes irreversible neuronal degeneration—is only around four minutes, although cooling the body to slow metabolism or applying artificial ventilation can hugely extend this window.
At a cellular level, tissues rely on a constant supply of oxygenated blood for their mitochondria to produce adenosine triphosphate (ATP), which provides energy for the myriad processes that are essential to the functioning of living cells. ATP is consumed by cells almost as quickly as it is produced, and until very recently it was thought that a few minutes disruption to ATP production would cause irreparable tissue damage; however, recent discoveries have caused a rethink.
When researchers deprived laboratory-cultured heart cells of oxygen, the cells took hours rather than minutes to die. Although a few minutes without oxygen is enough to send heart and brain cells on a seemingly irreversible path to extinction, the destructive processes do not actually begin for several hours. Cells remain intact and viable in a low-energy state for an extended period before they die.
Why is it, then, that irreversible brain damage occurs after just four to five minutes without oxygen, and that doctors can’t revive a patient after an hour if the body is still in good condition? The answer is surprising. Cells that have been without oxygen for more than five minutes aren’t critically damaged by the cessation of oxygen, they die on reperfusion— that is, on resumption of an oxygen supply. Instead of returning the body to normal function, a jump-started oxygen supply causes oxidative stress.
This is because in the absence of oxygen, precursors to harmful free radicals build up in heart and brain tissue. When the blood supply is restored, white blood cells coming into contact with these compounds produce an inflammatory response, releasing signalling molecules and free radicals. Such reactive molecules directly damage cells and also initiate apoptosis, or cell suicide, a process significant in embryonic development and a defence against damaged or cancerous cells. Once oxygen is reintroduced, we literally self-destruct.
The standard emergency treatment for victims of cardiac arrest—oxygen, defibrillation and epinephrine—now appears the one most likely to kill them, unless it is initiated within just a few minutes of collapse or unless the victim has been lucky enough to receive CPR prior to hospitalisation. New approaches are therefore being developed, centred round the idea of lowering body-core temperature and artificially circulating fluids to normalise physiology before attempting to restart the heart.
A recent trial at four US hospitals that utilised this approach was dramatically successful. Medics introduced an icy saline slurry, developed at the University of Chicago’s Emergency Resuscitation Center, into and around veins and certain organs. Circulated by a heart-lung bypass machine, the mixture rapidly induces hypothermia, allowing blood chemistry to be adjusted for gradual and safe reperfusion. Eighty per cent of heart-attack patients recovered, compared with a more usual survival rate of 15–18 per cent. This new methodology again moves the goalposts: even being dead for an hour or two might not be fatal.
The advent of modern life-saving procedures has blurred our understanding of when a person (or animal) can be considered to have died. Some surgery, such as the removal of cerebral aneurysms, can require that a patient be rendered in a state analogous with clinical death (or even embalmment) for the duration of an operation: the body is cooled, the heart stopped and blood drained from the vascular system. Under these conditions the brainstem and cerebral hemispheres fall electrically silent. At the end of the operation, which might take an hour, warmed blood is reinfused and the patient resuscitated. Anyone undergoing such an ordeal could, by any reasonable measure, be declared incontrovertibly dead, but if they recover, it follows that they were not.
Given then that we can no longer declare someone dead at the onset of heart failure, when should we suppose that they are dead? Should an individual be considered dead when resuscitation has failed, or at the moment a decision is made not to resuscitate, or when they reach a point beyond which there is no prospect of successful resuscitation? How can any of these decision-based events be measured against a physical state except in the abstract? Is irreversibility the key feature of death, and how does one locate that threshold? Or should we, for convenience, nominate a threshold organ other than the heart as a signifier of death when it too falls silent?
While irreversibility is commented on in medical literature and certainly provides the benchmark for advanced surgical procedures, there is a threshold organ that has taken on the mantle previously held by the heart. In New Zealand, as elsewhere, a person is considered medically dead on the demise of their brain.
As practices go, a brain-death criterion raises few objections because it aligns with the presumption that a persistent vegetative state—in which there is no electrical activity—indicates an end to consciousness. The value we place on consciousness is the key. We perceive little value in a living body that cradles a dead brain, yet we will fight tooth and nail to rescue a living brain in a dying body.
Brain death as our threshold criterion has the added benefit of being tidy. Diagnosis is based on a standard clinical examination, and when performed accurately it is considered unequivocal. Accepting that death has occurred when all electrical brain and/or brainstem activity has terminated is not without its problems, though. When a body is kept alive on a ventilator, it can contain a dead brain but still have the physical appearance of someone who is merely sleeping. To have a family member pronounced dead in this state is difficult to rationalise. This has led to celebrated instances where family members have refused to agree to the withdrawal of life-support, or attempted through the courts to force hospitals to maintain life-support. Such cases are generally packaged by the press as disputes about whether a family or a medical facility should preside over an individual’s “right to life” (i.e. their right to medication), but legal arguments normally hinge on measurements of brain activity.
As well as being the centre of all consciousness, the brain is the regulator of the vital processes of the body. Total brain death, in the absence of artificial life-support, means no part of the body has the independent wherewithal to survive. While it is sometimes asserted that some parts of the body do survive for hours or days post-death, there is no foundation to this view. The oft-quoted growth of fingernails and hair on corpses is illusory—dehydration causes flesh to pull away from hair and nails, giving an appearance of growth.
Like the graduated failure of other organs and systems in the body, the death of the brain does not generally occur in a given instant. A brain spirals into death, shutting down in a sequence from top-level activities, such as those of the frontal and prefrontal lobes, which house intelligent thought, decision-making, complex social emotions and memories, to the primitive regions of the brain housed in the brainstem.
The brainstem, which is little more than a swelling at the top of the spinal cord, is popularly referred to as a “crocodile brain”, because it resembles the complete brain of a modern reptile. It is similar to structures that appeared in organisms 500 million years ago, and it controls basic bodily functions, including breathing and heart rate. Even when the neo-cortex has fallen silent, indicating consciousness has ceased, an active brainstem can maintain neurohormonal regulation, keeping the body’s fluids and electrolytes in balance.
Because it can be difficult to determine whether someone is dead even with sensitive machines, paramedics do not usually have the authority to declare a patient dead unless that diagnosis is unequivocal. Under emergency protocols, resuscitation attempts must be continued until the patient is examined by a doctor, which is why so many persons are declared DOA (dead on arrival at a medical facility). Electroencephalographs (EEGs), which record electrical activity in the brain, are the best aids to making this judgement.
But even EEGs are not infallible. They have been known to detect erroneous impulses, and there have also been rare cases in which electrical activity has been too low to detect. To guard against this, hospitals may monitor EEG readings at intervals and declare death only when an EEG has been flat for an extended period. A special brain X-ray can also detemine if blood flow is present.
Once a brain-death diagnosis has been made, all life-support can legally be removed, although if organ donation for transplantation is a possibility, life-support may be maintained. Indeed, only organs removed in such circumstances are acceptable for transplantation. In New Zealand, it is usually only some accident victims, typically those who have suffered head injuries, who make suitable organ donors. In the United States, where gun ownership is enshrined in law, there is a steady tide of otherwise-healthy gunshot victims dying on life support who are good candidates for organ donation. In China, the practice of executing prisoners after establishing a donor match has created a burgeoning marketplace for body parts. Thus, New Zealand has a proportionally smaller pool of organs available for transplant than these and many other countries. You can refer to your driver’s licence to see whether you have volunteered your own corpse for organ harvesting—although at present relatives can, and generally do, overrule a person’s decision to donate.
Death and beyond
For the living, death is life’s dreaded moment. Humans know its inevitability and vividly contextualise it. There are many religious and cultural traditions that claim knowledge of what awaits one after death, and all of this knowledge is mystical in nature. Science has no information about any continuance after death. Nothing vital (other than microbial life) can be detected on or around a corpse, and no verifiable transmissions have ever been received from the dead. Despite this, religious and mystical traditions universally treat death as a transit point, the moment of birth into another life, rather than simply a termination of this one. For adherents to these traditions, immortality is a given—albeit in an altered state of being—but the expected quality of the afterlife is based on a judgement of deeds while alive on Earth—an incentive to moral conduct.
Indian-based religions, like Hinduism, Jainism and Buddhism, view death as the soul’s abandonment of the body, and an accumulation of earthly credits or demerits dictates the form of rebirth. This has echoes of the Biblical/Qur’anic view of judgement, except that death in the Indian doctrines is viewed as the apex of the revolution of a wheel, as worn-out humans, having failed to overcome life’s vicissitudes, are recycled into newly minted bodies for another attempt. Only those who attain enlightenment transcend the cycle and gain a paradoxical peace of no return—a reversal of the logic of the Abrahamic religions, life’s greatest goal being the avoidance of pesky immortality through endless reincarnations.
Funeral rituals for all religions are therefore rites of passage, and such rituals exist in all cultures and have existed throughout recorded and archaeological history. Archaeologists even cite evidence of ritual burials among extinct pre-humans, Homo neanderthalensis, who made careful graves, ornamented corpses with ochre and buried them with weapons, tools and other items for use in the afterlife.
The universality of belief in an afterlife perhaps hints at the power that the threat of personal extinction can exert over our imaginations. Modern neurobiology has mapped out the parts of the brain that are involved in intellectual, emotional and cognitive interactions (see brain-map sidebar), and we can reasonably suppose that these mental activities cease with disintegration of the neural substrate. Souls, on the other hand, which are an important theological concept, cannot be proved to exist, and neither can they be proved not to exist. But such a lack of scientific measurement does not apply to the physical act of dying. We now have considerable information regarding both the subjective experience of death and how this personal experience might be partially accounted for by known physiological processes.
First-hand descriptions of the death experience should be viewed as suspect if a narrator claims to be dead or in contact with the dead—although mediums and shamans might disagree with this point—but compelling subjective accounts do arise out of the near-death experience (NDE). NDEs are reported in a significant portion of those revived from impending death or otherwise on its fringes. NDEs can even be found in literature dating to antiquity. The oldest to be documented is the legend of Er, from Book Ten of Plato’s Republic (360 BC).
Er, a soldier, apparently slain on the battlefield, regains consciousness on his funeral pyre. He speaks of a strange journey to a place where judges sit between openings in heaven and earth, sending unjust souls downward to a place of dreadful suffering, and the righteous aloft to a “place of delights… beauty beyond words”. In this place, where the heavens are girded with pillars of pure light, Er encounters streams of humanity going toward an afterlife and, having completed a thousand years of bliss or torment, heading back to Earth to be reincarnated.
Stories like Er’s now have a familiar ring to them. Given a steady improvement in resuscitation and other first-aid techniques, NDEs have become commonplace. George Gallup, on the basis of polling reported in his book Adventures in Immortality (1982), calculated that millions of Americans had had such an experience. Typically an NDE is characterised by: an out-of-body sensation, especially of floating or flying above the body; bright lights, tunnel vision, or flying along a tunnel toward a growing light; vivid dreamlets or visions, often with a euphoric dimension and a strong sense that what is being imagined is real; a deep feeling of pleasure or peace, or sometimes dread; family and friends, including the deceased and even the living, appearing in a story line; and strong religious elements, such as encountering saints or scriptural characters and arriving in heaven or hell.
Intriguingly, the few accounts of NDEs from medieval times (when pulpits were fiery and inquisitors all the rage) mostly involve descents into hell. Visions of heaven or peace are more normal in contemporary experiences. Story lines vary with a cultural weighting, too. A Christian’s account might include biblical figures, whereas a Hindu is more likely to encounter characters of Vedic origins, and children usually find themselves surrounded by what they know—their friends and people who are still living. But cultural profile does not play a part in other elements of these descriptions, for which explanations might be found in brain chemistry.
Out-of-body experiences will reliably occur given the right pattern of stimulation. Neuroscientist Michael Persinger demonstrated that he could induce out-of-body experiences in anyone by subjecting their temporal lobes to patterns of magnetic fields. Swiss neuroscientist Olaf Blanke and his colleagues discovered that they could induce comparable effects through electrical stimulation of the right angular gyrus in the temporal lobe. Many chemicals, such as atrophine and LSD, will also stimulate this response. That there are receptor sites in the brain for such chemicals means that there are naturally produced chemicals in the brain which, under certain conditions (the stress of trauma, for example), can induce any or all of the feelings described in an NDE.
Some aspects of NDEs can even be replicated in unlikely settings. During aerial-combat manoeuvring in modern aircraft, fighter pilots and aircrew are subjected to huge, sudden accelerations. These accelerations can produce forces of eight or nine times standard Earth gravity. This means that a 75 kg man becomes a 675 kg man, and under these circumstances, blood flow to the head is severely reduced as it pools in the abdomen and extremities. Pilots and crew normally lose consciousness under this level of stress.
Trying to minimise the risks for those handling aircraft undertaking high-speed manoeuvres, the USAF School of Aerospace Medicine in Texas conducted studies into gravity-induced loss of consciousness (G-LOC) by simulating high G-forces in a giant centrifuge. On regaining consciousness, subjects described their experiences in terms very similar to those used by people who have undergone NDEs: tunnel vision, vivid dreamlets, euphoria, out-of-body travelling and bright lights. What both types of trauma—death and G-LOC—have in common is a sudden interruption of blood flow to the brain.
Yet another group who encounter a similar suite of experiences are people who take the dissociative drug ketamine, which is used as an anaesthetic and has hallucinogenic side effects. In this case, however, oxygen deprivation to the brain is not involved, but there is still a link. Ketamine binds to a class of brain receptors, the N-methyl-D-asparate (NMDA) receptors, which are at the forefront of activity in an oxygen-deprived brain. These receptors normally bind the neurotransmitters aspartate and glutamate.
When blood flow to the brain is reduced, oxygen deprivation acts as a trigger for the release of glutamate, which floods the brain. Brain cells rely more heavily than other cells on aerobic respiration because they store almost no glucose for emergency energy production in the absence of oxygen. Deprived of energy, neurons become depolarised as potassium ions leak out and sodium and calcium ions rush in. This sets up a chain reaction in which the pumps that usually draw neurotransmitters into the cells go into reverse. As glutamate is released, it triggers neighbouring neurons into firing (when they should sensibly be conserving energy), adding to the glutamate flood. This deluge of glutamate over-activates NMDA receptors, and many cells self-destruct, via apoptosis. In response, the brain releases ketamine-like chemicals that bind to NMDA receptors, effectively creating a blockade.
While this action protects brain cells from glutamate toxicity, it produces hallucinogenic effects matching those of ketamine. This state, in concert with neurons firing at random throughout the brain, might account for much of the content of dreamlets. In areas like the frontal cortex, where long-term memory is located, rapid-fire synaptic activity could be expected to produce something akin to the cliché of your life flashing in front of your eyes.
In the visual cortex, most neurons are aligned with the centre of the visual field. Computer modelling suggests that random firing of these neurons produces a tunnel effect with a bright light in the centre (refer Dying to Live: Near Death Experiences, Blackmore, S. 1993). As neuronal excitation increases, the spotlight effect expands. Flashes further out create a sense of motion, because the brain interprets any random movement on the periphery of the visual field as forward motion. The net effect is one of zooming down a dark tunnel toward a bright light, which grows to fill the entire visual field.
The brain habitually attempts to make sense of its situation and tends to string together a story line to fit the circumstances. An example of this routine mechanism is the way that a ringing telephone or other external stimulus becomes threaded into a dream. The spell is broken only by cognitive dissonance: when you lift the receiver (in your dream) and the phone paradoxically continues to ring, you awaken. But in death, the brain is in partial sensory isolation and further stressed by hallucinogenic and dissociative effects. Aware that death is approaching, a mind might draw on any preconceived notions it has to make sense of what is happening, interweaving this interpretation with its own desperate activity.
All of which provides a physiological model for near-death experiences, but there is no guarantee that this is an exact description of death. There is one major difference between the NDE and the actual death experience, namely that death entails no period of recovery. In an NDE the brain revives while it is still in sensory isolation, which could account for some—or even encapsulate the richest portions—of the NDE.
That said, death contains the same basic ingredients: a glutamate flood, hallucinogenic brain chemicals, lights in the visual cortex, and random firing of neurons throughout the brain. Those who have NDEs normally report losing their fear of death.
Life Expectancy in New Zealand has increased dramatically in recent years. Statistics reveal that we are dying older. The median age at death is now 76 for males and around 82 for females. In the last 25 years, male life expectancy at birth has increased by a staggering 10 per cent, while female life expectancy has improved by 8 per cent. That equates to an extra 7.3 years tacked on to the end of your life if you are male and 5.7 years if you are female. This trend was expected to abate as a “natural ceiling” was reached, but it has not. If there is a natural ceiling for the human life span, we don’t yet know what it is.
If you hail from Polynesian stock, you have less to cheer about. Polynesians enjoy shorter life spans than others in New Zealand. Maori life expectancy at birth is 69 for males and 73 for females, on average 8 years less than for the general population.
Worldwide, longevity is strongly linked with social status, and this is true in New Zealand too. A greater proportion of Maori and Pacific Islanders live on lower incomes and in poorer areas (see deprivation scale) than non-Polynesians, so lifestyle is probably a factor. But even when mortality is measured within social classes, Maori and Pacific Islander mortality is markedly higher.
In the last two centuries, improved sanitation, nutrition and health care have been responsible for increasing life expectancies around the world. Enclosing sewers has provided the biggest boost.
From an individual viewpoint, a longer life span is welcome; governments, on the other hand, may think differently. Their loyalties are split between the welfare of the electorate, managing the economy and being re-elected—the last of these being a diminishing prospect for those who choose to ignore urgent problems to focus on future ones. The accepted paradigm that a life spent paying taxes equates to a well-earned retirement does not take into account the seemingly trivial point that taxes paid today are spent maintaining social services today. As average life expectancy increases, degenerative diseases affecting senior citizens require ever more money creating problems for medical services. We may like the thought of living longer, but the reality may be unappealing if the state and the taxpayer cannot afford to cope with pensioner needs.
Growing concern has stimulated the New Zealand government to invest heavily in a superannuation fund so as to create a buffer against the worst effects of this impending pensioner surfeit. And in recent months, the government has also launched its KiwiSaver scheme, which should lessen the number of retirees entirely dependent on pensions. But will these measures be enough?
Biogerontologists, who study ageing processes to uncover the recipe for longevity, suspect the baby-boomer spike looms as a foothill that obscures a much larger mountain beyond. Raymond Kurzweil, a noted futurist in the United States, outspoken on the subject of life extension, is one of a growing number who believe that the prospect of human immortality is only decades away.
Kurzweil bases his conjecture on converging technologies. He thinks that the growth of cell-biology technologies and genetic engineering, coupled with recent extraordinary advances in nanotechnology, are the key. Kurzweil is a member of the US Army Advisory Board and has had the ear of successive US presidents on the subject of nanotechnology. He predicts that within present lifetimes we will be building miniature robots, no bigger than blood cells, that can swarm through our circulatory systems, repairing damage, combating disease and optimising DNA and other cellular structures.
His speculations sound like science fiction, especially the suggestion that we are so close to such a future, yet who would have believed in the imminent ubiquity of iPods, GPS and the Internet a mere 20 years ago? Kurzweil has his critics, but even conservatives in the field of anti-ageing medicine think that tissue-rejuvenation techniques, xenotransplantation and cell-engineering will push life spans to new limits, possibly running to hundreds of years, and that a portion of these gains could be realised by people who are alive today.
However, requisite technologies are either in their infancy or their advent is based on models that predict an exponential advance in technology. And we don’t know if there would be a limit to the human life span in the absence of the things we know about that kill us. Do other demons lurk in our internal architecture?
In the modern world, just as in the ancient, humans who escape all the diseases, accidents and forms of self-destruction that can prematurely claim their lives die as a consequence of organ failure. Cells die off or enter cellular senescence (having lost the ability to divide), and with fewer healthy cells, organs are less able to regulate internal equilibrium or to respond to stress, making the organism susceptible to disease. Underperforming organs impose systemic stress, leading to a cascade of organ failure.
This prosaic death is what is normally referred to as “dying of old age”. If you are reasonably healthy it will occur in your nineties, while those who are very robust will make it to something a little over 100. The oldest verified age a human has attained is 122.
But organ failure does not have to be fatal. Surgical replacement of failed organs and broken, diseased or worn-out body parts has become commonplace in modern medicine. In theory, it is a simple matter of replacing run-down components with newer ones, as you would for a car. The main drawback to the concept of organ donation as a routine life-extension practice is that vital-organ replacements come from other human bodies, making the supply very limited. There is also the problem of tissue incompatibility, meaning recipients of replacement organs require life-long immuno-suppression. Immune suppression commonly leads to a reduced life span.
Simpler body parts can be replaced more easily. Blood vessels, bone and membranous tissues can be grafted or surgically reconstructed from other parts of the body, circumventing rejection. Bones and joints are often replaced with metal, ceramic or high-density polyethylene implants, which do not trigger immune responses.
If we not unreasonably suppose that surgical techniques and autoimmune-suppression technology will improve, and that organs will become readily available through innovations in manufacture, animal sourcing or bioengineering, replacement surgery could go a long way toward ending premature death. Large-scale surgery will be more feasible if we can master the art of growing new organs from our own stem cells, an increasingly likely possibility.
But extending a person’s age into a second or third century presents another problem entirely. Organs are not the only parts that deteriorate with senescence. Skin, bone, flesh, joints, vascular systems, nerves, sensory receptors, hair and teeth—all these, too, lose vitality with age. However, life spans in a range of animals are surprisingly pliable. Mice or rats on near-starvation but nutrient-rich diets can live 30–50 per cent longer than normal. Calorie restriction has also been shown to extend life spans in yeast, worms, flies and monkeys. A near-starvation diet shows promise for humans too, but it reduces fertility and may have other drawbacks. Not the least of these is that feeling constantly famished could be considered an unrealistically high price to pay for a drawn-out retirement.
A family of genes known as sirtuins, which appear to regulate survival mechanisms in adverse conditions, are linked to this starvation effect, and manipulating them directly may prompt the same outcome yet remove the need for restriction of calories. Engineering extra copies of the SIR2 gene has increased longevity in organisms as diverse as yeast, roundworms and fruit flies.
Even so, after a predetermined number of generations about 50 in humans—cells become senescent and unable to divide further. Although cell senescence is a complex process, it appears to be tied to the gradual shortening of chromosomal telomeres as cells go through increasing numbers of divisions. Telomeres are long strings of simple repeating bases that, like the aglets on shoelaces, cap chromosomes. Each time chromosomes are duplicated during cell division, these end regions are eroded by a few hundred bases. Hence, telomeres are thought to prevent damage further along the chromosomes, where genes could be affected, by acting as a buffer.
But although they appear to function like expendable bookends, telomeres contain surprises. Many age-related diseases have been linked to shortened telomeres, although the basis of the effect is unknown. A study done with nematodes showed that a worm’s life could be extended 20 per cent by simply lengthening its telomeres. This result has not been replicated in higher animals, although normal human cells in culture have been able to undergo up to 90 divisions in the presence of an enzyme that lengthens telomeres.
Accumulated oxidative damage caused by free radicals holds another key to cell senescence. Indeed, some believe that ageing is just a manifestation of cumulative oxidative damage. Such damage is linked to a long list of age-related diseases including cancer, heart disease, stroke, arthritis, diabetes and neurodegenerative disorders such as Alzheimer’s. Some cancers are thought to result from mutations caused by free-radical damage to DNA.
Free radicals are unstable molecules with unpaired electrons, particularly reactive oxygen compounds. They are natural by-products of respiration and not altogether bad, playing a handy role in vital processes such as the intracellular destruction of bacteria.
Free radicals stabilise themselves by oxidising (hence damaging) other molecules, including proteins, lipids, carbohydrates, DNA and RNA. But as they are also necessary, the body uses mechanisms such as antioxidants to protect itself from them. Antioxidants are abundant in green plants, and a diet high in fruit and vegetables has been shown to lower the incidence of heart disease and all the other diseases associated with free-radical damage.
Antioxidants are also the cause célèbre of the cosmetics and vitamin-supplements industries. But beware: claims that antioxidants have anti-ageing properties when applied in petroleum-based creams or when taken in concentrated supplements are based entirely on test-tube reactions and a lot of hypothesis. While food is clearly a delivery mechanism to which we are adapted, megadose pills and creams have yet to prove their worth. It may be that humans absorb these molecules best by slow digestive release, or perhaps they are synergistically bound to other molecules in the food. A mounting body of evidence suggests that supplementary intake of antioxidant-rich compounds, including favourites such as vitamin C, vitamin E and beta carotene, might even be toxic in some situations. For example, a 1992 trial of beta carotene and vitamin A given to lung-cancer candidates (19,000 smokers and individuals who had been exposed to asbestos) by the US National Cancer Institute had to be abandoned when mortality rates increased among those receiving the supplements by 28 per cent over the control group.
Tantalisingly, cellular senescence is not universal in the animal kingdom. It is not observed in some lower organisms, including sponges and crayfish, giving hope that this human time bomb can be defused.
Many animals, of which the most advanced are salamanders, have another intriguing ability: they can regenerate entire organs and limbs. Humans are believed to have intact, but inactive, versions of the genes that enable these animals to do this. One gene which is active in newts when they are doing their regeneration trick, msx-1, has been identified in humans and mice, and scientists have already found a way to turn it on at will in mice in order to reconstruct damaged muscle cells.
This means that—in mice at any rate—not only are the genes present, but the intracellular signalling pathways are intact, too. Only the signals required to start the process are missing. If the same holds true in humans, we could see transplant surgery, and especially surgical repair of organs, replaced by regeneration therapy.
Transplantation and regeneration seem less feasible with brains than with other organs, but some biologists postulate that the human brain could survive in good condition for around 200 years were it not subject to the stresses imposed by less robust organs in the body. This idea is obviously untested; however, assuming it is sound, if we could slow degeneration in simpler organs, including the vascular system, this might be enough.
Every time a cell divides in your body, there is a small chance of a mutation arising because of errors made in the copying of its DNA. Hence, the longer you live, and the more divisions your cells undergo, the greater the odds of your developing a cancer. (That said, age-adjusted cancer rates around the world vary somewhat, so there is more to getting cancer than just accumulating years.) Not surprisingly then, as life spans have increased, cancer has become a leading cause of death. In New Zealand, cancer replaced heart disease in 1993 as top killer, and by 2001 accounted for 29 per cent of all deaths, with heart disease relegated to around 22 per cent. You could interpret this as meaning that we are now surviving long enough to be killed by probability.
Death by numbers
Life is a minefield—there are a lot of paths that lead to death, timely and untimely. You don’t even have to have been born to die. Most embryos do not survive the initial weeks of pregnancy—an estimated three-quarters fail to embed in the uterus or spontaneously abort.
This might seem a dreadful enough statistic for would-be humans, but at least these fellows make it over the first hurdle—just getting as far as fertilisation is becoming something of a coup in modern times. A growing trend toward infertility has reached near epidemic proportions worldwide, with around one in seven couples requiring medical assistance to conceive. The United Nations reports that fertility rates have dropped most alarmingly in the last decade in developed countries, with Europe in the worst decline.
New Zealand is not immune to this development. Annual birth rates suggest that New Zealand women average two births, which is below the level required for a population to replace itself without migration (2.1 births per woman are needed for a stable population).
If you have beaten the odds and been conceived (we’ll take that for granted if you’re reading this article), the fast-growing lump of cells destined to be the vehicle for your iridescent soul will find itself in a parasitic relationship with its host, your mother. This relationship is nothing short of warfare from the point of view of the foetus. The protein value of a mother’s diet during pregnancy does not affect the birth weight of a baby (except in cases of severe malnutrition)—the foetus lays first claim to all the nutrients circulating in the maternal bloodstream. Under such adverse conditions it can be hard work for a mother to survive pregnancy.
A woman can of course override her physiological largesse and choose to terminate her pregnancy. In 2005, 17,530 induced abortions were conducted in New Zealand, accounting for 23.3 per cent of all pregnancies. This figure includes abortions on the grounds of foetal impairment, instances in which the life or health of the mother was endangered, and cases of incest and rape.
Death in childbirth for mother and/or baby was very common before the 20th century, but it has become an uncommon death in the modern era. In New Zealand there were 360 stillbirths in 2005 (a rate of less than 1 per cent), and infant mortality (death at under one year old) was just 5 deaths per 1000 live births.
Among young people, motor-vehicle accidents particularly, and accidents in general, are the leading cause of death, although an increasingly micromanaged and regulated society has reduced environmental dangers overall. The most dangerous person you will ever know is likely to be yourself, and not just on account of your own tendency toward reckless behaviour when young. While murders account for a very low percentage of deaths, suicide rates are comparatively high, coming second only to road carnage for 10–24-year-olds.
Suicide is a uniquely human way of dying. Other animals don’t indulge in it, despite popular attempts to anthropomorphise their behaviour. Choosing to take one’s own life requires symbolic thinking abilities to overcome strongly instilled self-preservation instincts.
There is no such requirement, however, for self-sacrifice. Survival instincts can be overwhelmed by instincts to preserve one’s genetic legacy. We view altruism as almost superhuman, but there are numerous examples of animals that will sacrifice themselves to protect broods, or to divert attention from a group of relatives in peril.
Mostly, however, we die from disease. Remove cancer and cardiovascular diseases from the list and you eliminate three-quarters of death’s serial killers.
A place to die
Unlike Christa, who spent her final weeks in a hospice, Mum died in a hospital. The deterioration in her health was unexpectedly speedy on account of an infection and compounded by renal failure, which meant there was no opportunity for her to be moved elsewhere. Like Christa, though, she had access to pain relief. Death in any healthcare institution is managed so as to minimise pain and discomfort. The trade-off for such relief can be a loss of lucidity.
I spent her final night by her bedside. For most of that time there was no sign that she was aware of her surroundings or of my presence. She couldn’t talk, was almost blind, having lost the ability to keep her eyes moist by blinking, and had limited volition. Her breathing was extremely laboured because of fluid accumulation in her lungs; her kidneys, having shut down, had stopped transporting fluids. Her death came on a rising tide, but three or four times in the night she regained her faculties fleetingly, squeezing my hand, even smiling to let me know that she knew I was there. In the morning her breathing became more peaceful, then she died.
Dying in a hospice, Christa was strongly medicated to alleviate pain, administered in measured doses as she slipped in and out of fading consciousness. Her flights from reality and her loss of memory (and identity) could, in part, be attributed to these infusions. There is no question, given the pain she would have experienced as she starved to death, that this was a humane and commendable intervention. Who, when faced with such a harrowing outcome, would not trade some lucidity at the end of their life for effective pain relief?
Euthanasia is against the law in New Zealand and most other parts of the world, but I confess I am uneasy with this standard. Humanitarian instincts compel us to administer pain relief, if necessary to a level that can completely blot out identity, in order to preserve the apparent sanctity of what hangs off the bones of the terminally ill. I am as pathetically neurocentric as the next person and struggle to assign any real value to my life, separate from my identity, when I imagine it so reduced in quality. The legal standard that allows us to harvest organs from bodies with dead brains because they lack the ability to harbour identity and consciousness seems not to apply when absence of identity and consciousness is drug-induced and electrical brain activity is still present. It is hard to fathom. The implication is that electricity alone is a measure of intrinsic value.
But I digress. Despite my unease with the law over this issue, I consider hospices to be without peer among medical institutions. They are caring, thoughtful, high-quality providers of an undervalued service. Dignity and privacy are commodities beyond value to the dying, and hospices are rich in their provision, which is regrettably not always true of some production-line medical practices. However, only half of the total funding for hospices comes from the public purse, and even that has been hard won. For the rest, hospices rely on donations and interminable fundraising.
With an emphasis in the health sector on restorative medicine, it is not really surprising that palliative care has been neglected. Prior to the 19th century, care for the dying fell to families, with or without support from an affiliated church, but in 1897 the Irish Sisters of Charity opened a hospice in Dublin—the first established with the specific aim of caring for the dying. The hospice concept never really caught on, though, and by the middle of the 20th century, people were increasingly dying in hospitals or nursing homes.
The modern hospice movement is an innovation credited to British physician Cicely Saunders, who in 1967 founded St Christopher’s Hospice in London. What was innovative about Saunders’ approach was a shift in thinking: to treat dying as a medical event and to manage it with medicine.
New Zealand joined the movement in 1979, when the Mary Potter Hospice was founded in Wellington. It evolved out of the Mary Potter Ward at Calvary Hospital, which was run for the care of cancer patients by the Little Company of Mary, a Catholic nursing order.
Today the hospice movement has 38 New Zealand facilities, and care extends to supporting the terminally ill in their homes. The modern movement can be considered as much a philosophy of care as a physical entity.
There are plenty of sound reasons to bury or cremate the dead. A day after death, the first signs of decomposition become manifest. Without embalmment, a corpse can become dangerously unhygienic in a far shorter time than that normally allotted for disposal. The work of the funeral industry is therefore as much practical as cosmetic.
New Zealand law requires that a cause of death be established before burial or cremation proceeds. This requirement protects the public interest, as it ensures that crimes and other social threats, such as epidemics, are detected. Certification is normally obtained from a doctor, particularly when death is an anticipated result of a straight-forward illness. But when a death is unexplained or occurs in unnatural or violent circumstances, it is reported to a coroner, who then takes steps to establish the cause.
Beside suspicious or enigmatic deaths, those that occur during medical procedures, or when persons are in the care or custody of the state, are also referred to a coroner. A coroner may order a post-mortem examination or launch an inquest if they deem it necessary. A new coroner’s act now means that 14 full-time coroners are dispersed throughout the country.
Post-mortem examination (or autopsy) is a surgical investigation carried out by a forensic pathologist. It involves an external inspection and an internal examination, during which a careful scrutiny of organs and blood vessels is undertaken. In addition, samples of tissue, blood and other fluids are examined under the microscope and tested in the laboratory for any clues that might establish the cause of death, such as the presence of pathogens or toxic substances.
Pathology is the study and diagnosis of disease, and forensic pathologists are expert at teasing this information from the dead. Jane Vuletic is one such specialist, based at the coroner’s office at Auckland Hospital. In a day’s work she might confirm her suspicion that death resulted from coronary heart disease, or reveal the true cause to have been an infection that was masked by the symptoms of a known condition or by its treatment. Forensic autopsies can clarify the circumstances of death in a criminal inquiry, assist in crime-scene reconstruction, and uncover vital clues or furnish important evidence to the courts.
From this perspective, forensic pathologists combine the instincts of a detective with the knowledge and experience of a surgeon and the methodology of a scientist. Jane says that sometimes clues to the cause of death can be gleaned from the physical appearance and circumstances of the corpse (e.g. was the deceased found clutching at the chest?), while other times a definitive cause might only come to light under a microscope.
Checking for evidence of foul play is only one function of an autopsy. In determining precisely how, when and why a person has died, an autopsy can shed light on other diseases or conditions that went undetected, or highlight deficiencies in treatment regimens or hospital practices. All of which makes autopsy a valuable tool in the medical environment, especially given that even when a doctor is confident about the cause of a death, an autopsy will reveal them wrong a significant percentage of the time.
One US study of 1619 hospital patients, published in the Southern Medical Journal (2006), found large disparities between death certificates and subsequent autopsy results. Heart attacks were missed in 25 of 52 cases (48 per cent omission error) and ascribed wrongly in 9 of 36 cases (25 per cent commission error). Autopsies therefore act as an audit, useful for maintaining ongoing standards of care. Correlating the symptoms that patients present with and their cause of death can lead to better diagnosis. An autopsy can also shed light on pathological processes, which aids research and the development of medical treatments and procedures.
Not far from where I lived for a year or two in Melbourne was the old St Kilda Cemetery. I loved the place. Located in a central suburb of a bustling city, it seemed other-worldly, a misplaced piece of ancient Earth. So many cemeteries in New Zealand are well-ordered, featureless paddocks with lines of knee-high granite markers, but this leafy cemetery was filled with exquisite marble masonry, lavish weathered headstones bearing evocative inscriptions, trellised graves, and plots marked with broken angels and weeping madonnas. Many Melbournians have ancestral origins in the Mediterranean and have inherited a Greco-Roman élan when it comes to death.
A sense of reverence and style is present in Maori culture, too. Urupa (burial areas) are linked to marae, and families are usually buried together. The whanau urupa links people to the land that holds the source of their mana.
Tangihanga are held on the tribal marae. Here the dead are greeted, honoured, farewelled, and given over to the care of the long dead. Believing that a spirit is attached to a body until burial, speakers address the open coffin, and the tupapaku (body) is kept company until burial. Once released, the spirit travels to the tip of Cape Reinga as it begins its journey to join its ancestors in Hawaiiki.
Older settler cemeteries are quite similar to their modern counterparts in New Zealand. Headstones and raised plaques (their proportions ever-diminishing) are the notable feature of these places. The term headstone is now interchangeable with tombstone or gravestone, but it was not always so. A tombstone was originally the lid of a stone coffin, and a gravestone a stone slab laid over a grave. Today’s headstones are the modern versions of stelae, which were common to many ancient cultures, from Greek and Egyptian to Gaelic, Chinese and even Mesoamerican. They stand erect over graves as markers so that the dead can be located and, presumably, to warn against accidental disinterment. Made from the most permanent natural material available, a headstone allows an epitaph to survive all living memory of the deceased, making such a monument for many people an imposing legacy.
The modern trend is to opt for cremation, a counterpart of the traditional funeral pyre, an ancient method of disposal still common in countries like India.
Markers and headstones have become less lavish in these material times, reflecting a growing preference for reductionist disposal. It could even be argued that our steady drift from reverence for the dead can be traced to longer life spans as much as to secularity. Extended families are now less common in New Zealand than was once the case, and generational links have gradually been eroded. With modern social arrangements—de facto relationships, common divorce and remarriage and the emphasis on youth—death among the older generations (grand and great-grand) is often less personal than it used to be. If in the future we live to ages that make great-grand relatives common, we will probably become aware of their death only by chance.