If there is one thing we can be certain of in life, it’s that eventually we will die – that is, we will no longer be alive. Sadly we are not completely certain what “being dead” means: defining death is much more complicated than it appears, and it’s getting harder to define all the time.

As recently as a century ago, it was priests not doctors who declared a person dead. When in doubt, they looked for signs of putrefaction. As medicine advanced, however, it became apparent that death was not an event, but a process.

Even so, for practical purposes an arbitrary line had to be drawn. First it was taken as the heart stopping. Then came the notion of brain death and in the 1960’s this seemed like the way forward. For a while it was even considered foolproof: once activity ceases in the brain and brain stem you can never regain consciousness, and without intervention the body will quickly shut down.

But foolproof it is not, and the fact that several hundred neurologists and philosophers are gathering next May for the fifth International Symposium on the Definition of Death shows this only too well.


Technology brings problems

The real spanner in the works was the invention of ventilators – machines that keep lungs breathing and hearts pumping even after the brain has suffered extensive damage. This raised for the first time the question of whether people could or should be treated as dead simply because their brain was dead.

One set of philosophers argues that the destruction of the frontal lobes, with the memories and personality they store, is enough to declare someone dead. This definition includes those in a “permanent vegetative state“. Others resist the idea of brain death altogether and insist that the heart must stop beating before a body can be treated as dead.

The compromise “whole-brain-death” position, which has been written into law in most of the industrialised world, is that a person can only be declared dead if almost all brain function has been irreversibly destroyed.

Whichever definition is adopted, there are many practical and political implications: after all, doctors are generally obliged to treat the living and stop treating the dead. Some bioethicists have even proposed that individuals should choose their own definition of death.

As diagnostic technologies have advanced, declaring total and irreversible brain death has become ever more problematic. In the 1990’s medical advances allowed residual brain activity to be detected in many patients who would have previously been considered brain-dead.

Death of identity

The growing ability to compensate for loss of the brain’s regulation over the body means doctors can maintain some brain-dead bodies indefinitely. We have also discovered more about the brain’s self-repair mechanisms and are rapidly developing new ways to repair damaged brains. It may soon be possible to engineer new neural tissue from patients’ cells and transplant it into damaged areas. Progress in nanotechnology and the miniaturisation of computing will also eventually allow brain damage to be repaired with implantable machines.

All these advances make defining brain death increasingly difficult – and our ability to rebuild destroyed brains may eventually force us to develop a brand new definition of death, based not on brain activity but on personal identity: would you be the same person if your entire brain, including all your memories and personality, were destroyed and then grown anew?

What is it like to die?

It seems it is not death per se that scares most people: once you’re dead (really dead, that is) you won’t know anything about it. What does seem to frighten people is the process of dying, and whether it will be painful. So do we have any idea about how it might feel to die? Of course there are not many people to ask.

But a few people have died and been brought back. Their tales, together with extrapolating from medical experience, can shed light on what it’s like to meet your end in various different ways: from electrocution to hanging, and from drowning to lethal injection (beware – this article is not for the faint-hearted!). The latter – lethal injection – is another extremely contentious issue. It’s been branded too unreliable, too painful and just plain inhumane.

But it’s not always blood and gore: if you’re lucky enough to die peacefully of old age, that is.

Dealing with loss

Another potentially frightening event is the death of a loved one. It can certainly be a very sad and painful time. There are thought to be five main stages of grief: disbelief, yearning, anger, depression and finally, acceptance. The most common emotional difficulty experienced is, unsurprisingly, emotional loneliness.

Losing a partner is generally assumed to be one of the most stressful experiences that people encounter. Marriage is such a strong bond that if one partner dies, the person left behind is put at a significant risk of following suit: it’s known as the “widower effect”.

The science behind how grief affects the body is still in its infancy, but it is thought to act via stress. Lack of close support can also increase risky behaviour, such as heavy drinking. And the risks differ according to the way a person dies: if somebody dies of an illness that needs prolonged and burdensome care, then their surviving partner has a higher chance of dying.

It is a curious fact that the widower effect tends to affect white people more than black people; perhaps because elderly black people tend to receive more support from friends and family than elderly whites.

For those married people who think this appears too bleak, don’t despair: marriage is intrinsically healthy. The elevated risk of dying associated with losing a partner is lower than for those who are single or who never married.

Animals feel grief too

It seems that it’s not just humans that experience grief, animals also appear to do so. Elephants are thought to mourn the dead, and gorillas have been seen holding wakes.

It is not just the loss of someone close that appears to induce grief. Take the tragic deaths of people caught in the 9/11 bombings or the death of Princess Diana. This may not be grief after all, but rather a morbid fascination with death. Many people engage in an increasingly popular pursuit known as dark tourism, which involves visiting sites where people have suffered or died in tragic circumstances, such as the killing fields of Cambodia, the ruins of New Orleans, or the extermination camps of Auschwitz-Birkenau.

The motivations behind dark tourism are not clear-cut. Sometimes it is to pay respects to a loved one, but it may also be to connect with an event seen on TV, to learn more about what happened, or simply out of curiosity. Or perhaps it’s because death has been almost completely hidden from everyday life in most developed countries that people feel the need to readdress this balance.

What happens after death?

So when it comes to death, what are we sure of? Well we know what happens to your body from the moment you leave it. Unless frozen or mummified, dead bodies inevitably decompose.

As soon as the heart stops, gravity takes hold. Sometimes only minutes after death, a purple stain appears where the blood settles in the lowermost parts of the body. The skin and muscles sag, the body cools, and within 2 to 6 hours rigor mortis sets in.

Starting with a stiffening of the muscles in the eyelids, it spreads throughout the body before the muscles relax again. Rigor mortis can last between 1-4 days depending on various factors, not least the ambient temperature.

Two or three days after death, the body starts to putrefy. Bacteria which normally inhabit the body, especially the bowel, take over. The first sign of putrefaction is a green discolouration, which eventually spreads over most of the body before turning it purple and finally black.

Decomposition and deduction

Bacteria in the intestine produce a rank-smelling gas which bloats the body and makes the eyes bulge. A week after death, blood-coloured blisters appear on the skin and the slightest pressure causes the top layer to slip off. After 3 to 4 weeks, the hair, nails and teeth loosen, and the internal organs disintegrate before turning to liquid.

Finally, nothing is left but the skeleton. Is it true that hair and finger nails grow after death? The answer is no: they just appear to as the skin dries out and shrinks away from the hair and nails.

Decomposition is often very useful to forensics experts who can deduce when death occurred by looking at the stage a body has reached. Forensic entomologists can even look at larval stages of insects in corpses to work out the timing of death, although this might not be as accurate as once thought.

There are also chemists who are developing a “sniffing detective” – a device that can measure the volatile gases given off by a corpse at the different stages of decomposition – they hope it will aid forensics.

Disposing of your body

And then there’s the question of what to do with your body once you no longer inhabit it. The choices are endless: you can be buried in a coffin in the ground, or cremated, and now there are more environmentally friendly ways to go: you can have your body freeze-dried and then shattered to make a soil-enriching powder, or have a woodland burial – where your body is wrapped in a cloth and left in the soil to provide compost. Or perhaps you might want to be put on public display, or have your ashes turned into a strange work of art with its own mortality – or being a New Scientist reader, you might fancy donating your body to science.

For those who want to play a long game, there’s always the option of having your body frozen. Researchers have had success with reviving frozen organs, and if the more fantastic goal of bringing someone back to life after a spell in the freezer remains elusive, at least research is telling us what it would take to perform such a miracle.

Life after death?

Perhaps the most intriguing question for many people is whether or not there is life after death. A few have even concocted truly astonishing experiments to find out. Not surprisingly, they have failed to come up with credible answers. There is a train of thought that near-death experiences might offer a clue, although researchers think they are simply an illusion related to REM sleep.

In the developed world, most people are lucky enough to live lives that end as a result of ageing and its associated diseases, rather than because of premature death due to infectious disease or accidents. As result, we are able to repress our fear of death by not thinking about it much.

The age at which people need to think about death is constantly being pushed back because of better nutrition and medical care. Technology promises to continue this trend: stem-cell therapy and brain prosthetics promise the possibility of reviving and rebuilding brains currently diagnosed as dead.

Doctors are also getting better, albeit slowly, at resuscitating patients who in the past would have died. Some researchers are even experimenting with suspended animation as a way to protect seriously injured people until they can be transported to an operating theatre.

What does the future hold?

The continual rises in human life expectancy now suggest there is no maximum lifespan, and research, for example into stem cells, free radicals, and even social status, is suggesting how we can reduce the number of avoidable deaths. There’s also plenty of advice on how you can maximise your own lifespan.

But if we could all live into the hundreds and even beyond, what sort of world would it be? Initially it could be difficult – as life spans increase, we may be exposing ourselves to a rather bleak future in which we all spend a large proportion of our lives old and ill. And even if we conquer ageing as well, we will have some heart-wrenching moral dilemmas to face as the planet becomes progressively more overcrowded. There is a way out, though. If some futurists have their way, death will be replaced by uploading ourselves onto computers. That will solve the overcrowding problem, no doubt, but expect a run on computer memory.

Perhaps it is only taxes that are certain after all.

Death – Delve deeper into the riddle of human mortality in our special report.