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When We Die
The Science, Culture, and Rituals of Death
By Cedric Mims St. Martin's Press
Copyright © 1998 Cedric Mims
All rights reserved.
ISBN: 978-1-4668-8385-7
CHAPTER 1
What is Death?
When I consider the short duration of my life, swallowed up in the eternity before and after, the little space which I fill, and even can see, engulfed in the infinite immensity of spaces of which I am ignorant, and which know me not, I am frightened, and am astonished at being here rather than there, why now rather than then ... the eternal silence of these infinite spaces frightens me.
From 'Pensées', by Blaise Pascal, French mathematician and moralist (1623–62)
The Death of Cells
In the body cells are always dying. Blood cells, cells in the skin, those lining the intestines: all are either shed like leaves or degenerate and die. A white blood cell lives for only a few days, and each day we lose millions of cells from our skin and intestines. The fine white dust that you pick up on your finger when you run it over a shelf or other surface consists mostly of dead skin cells, and during a lifetime each of us sheds about 18 kg of skin. The live, naked cells lining the intestines suffer continual physical damage, and are shed after a few days. To replace all these lost cells and keep the body intact, other cells are constantly dividing. Cell death is therefore the natural state of affairs, and 'In the midst of life we are in death.' That passage from the the service for the burial of the dead in the Book of Common Prayer takes on a biological meaning.
You could say that these cells don't have to die, and that nature could have arranged for them to live much longer. But at the skin surface and in the intestine the inevitable mechanical damage is best met by continually shedding cells and replacing them with new ones. And the white blood cells, armed with powerful chemical weapons for use against invading microbes, need to be regularly dismantled and replaced by new ones. It is a common belief that cells in the test tube go on multiplying for ever. But the fact is that no cell can manage more than about sixty divisions (see chapter 4). After that, the cell ages and dies. A few types of cell, like nerve cells or heart muscle cells, stay as they are throughout life, all the time recreating themselves as old molecules are replaced by new ones, but not actually dividing.
The reasons why cells have to die becomes more obvious when we consider the development of the embryo. During this period the growing organs are always having to be remodelled and reshaped. Certain structures have to be demolished and cells destroyed. Our tail and our gill slits, for instance, present in the early embryo as we recapitulate our origin from primitive vertebrates, must be altered and diminished at later stages in development. In the same way the tadpole's tail is disposed of as the tadpole turns into a frog. As these events unfold, cells have to be killed off. A great deal of destruction accompanies the process of construction. Accordingly, to take care of these needs, all cells have a special 'autodestruct' or suicide program built into them. It can be switched on as required, and is an essential resource during development, and in certain infections when cell suicide is the best strategy for defeating the attack. It is called 'apoptosis' and is described in chapter 4.
The Necessity of Death: Nature's Strategy
Life is a process of constant change. All living things must reproduce and multiply, and when they die their offspring take their place. But the places are limited. The opportunities, or in modern jargon the ecological niches, are not infinite. There is a limited amount of room on the earth. This means competition, and the best fitted ones are going to survive and out-reproduce the others. This is how evolution works. Without death, the world would soon fill up with whatever creatures were present at the time, and there would be no more change, no more evolution. Without death, a single cell, after dividing each day for many weeks, would have produced hundreds of tons of cells and these would rapidly cover the surface of the earth. Nature is so prolific that death has to take a hand, even at the level of the elephant. If a female elephant bore six young during her lifetime and they all survived and reproduced at the same rate, then after 700 years the descendants of a single pair would number about 18 million. Hence the struggle for existence. Death is necessary. To die and leave the stage is the way of nature. It was put simply by the French moralist Montaigne (1533–92) in his essay 'To Study Philosophy is to Learn to Die': 'Give place to others, as others have given place to you!'
Death takes other things besides the individual at the end of life and the cells in the developing embryo. Certain objects are needed at one time but can be discarded when they have served their purpose. The placenta is doomed to die after the birth of the offspring, and is usually eaten by the mother (except in human beings). The umbilical cord soon dries up and dies, leaving its mark. Adam, strictly speaking, should be represented without a navel.
Why, we might ask, has nature chosen the strategy of death, the strategy of billions of short lifetimes, rather than some other basis for life? It is because this is the only way to ensure change, which, together with competition, is the driving force of evolution. The ultimate reason for sex is that it is a method for mixing together the genes of different individuals. It increases the variety of gene mixtures, and gives evolution something to work on.
The best way of looking at it is to remember that your germ cells (eggs, sperm) are fundamentally different from the rest of you. These cells, or a few of them at least, will outlive you, surviving after the egg has been fertilized and then dividing to form a new individual, your offspring. All the rest of you, all your somatic (bodily) organs and cells, die when you die. It is your DNA, your genes in the eggs and the sperm, that survive in your descendants. This is the pathway for changes in genes being handed down through the generations and allowing evolution. You and your body are no more than a device by which the germ cells ensure their immortality. To put it the other way round, your body sacrifices itself so that the germ cells can live on. Nature cares about the survival of your DNA rather than the survival of you yourself. The distinction between the immortal line of germ cells (the germa) and the mortal rest of the body (soma) was made more than a hundred years ago and is a useful one.
Why Immortality would Raise Problems
One other possibility would have been for nature to have produced superorganisms that never aged or died. But agelessness would have serious drawbacks. First, it would have made it impossible to achieve the drastic transformations in living creatures over millions of years that were needed to adapt to changing conditions. Animals and plants have had to undergo fundamental changes in response to alterations in climate, food, predators and so on. They did it by producing new individuals (offspring) at regular intervals, each generation showing slightly altered features. This allowed for change. The penalty for failure to change and adapt was death. Second, it would mean that as the old individuals accumulated there would soon have been no room for future generations. Third, there are daunting biological problems in designing an immortal.
One of these biological problems concerns DNA. Our genes have to put up with constant low-grade bombardment and irradiation damage which comes fom rocks and from outer space. All cells make occasional mistakes when they are making a second copy of their own DNA in preparation for division. These changes in DNA are called mutations, and they are nearly all harmful. Initially, most of the changes are corrected or repaired, but as cells get older they are less able to carry out the repairs. The DNA abnormalities accumulate and cell functions are interfered with. This has a lot to do with ageing and cell senescence, and is dealt with in more detail in chapter 4. How would the immortals get round this problem? An immortal species, if ever it arose, would be staking its existence on a single solution to the problem of survival: its solution. Assuming that thousands of other species were still around, these would still be undergoing the relentless change and adaptation that has been the stuff of life ever since it began. The immortals would have to watch out and keep these other species in their place, not permitting any developments that might threaten their supremacy. They would also have to control their own numbers at an optimal level for the environment. They would have to look after their own evolution, and in doing so would be distorting the archetypal rules of the game. They would have replaced nature.
Am I giving a description of the human species at some distant future time? Once all the secrets of DNA are solved and we know exactly how to make whatever we want, there will – theoretically – be no limits on what we can do to manipulate human development. We have probably already exempted ourselves from the ancient rules of nature, because the 'unfit' now survive; and little is known about what changes this is making in our gene pool. Once we had the capacity to modify, change, even improve our genes in the laboratory, we could take over our evolution – as we have already taken over the evolution of dogs, cats, cattle and other domestic animals. It seems unlikely that our present characteristics, the ones that evolution selected out as best for a hunter-gatherer life 100,000 years ago, for a life of uncertainty, famine and disease, would be appropriate for human life in the distant future.
Contemplation of such possibilities arouses a host of ancient fears. What opportunities for madmen, for despotic rulers, for mad or at least unethical, scientists! Words like 'cloning' (see chapter 12) add to the foreboding, and we regard this picture of the future with dismay. But it will almost certainly come to pass, and will probably not be so bad as many fear. For the apprehensive, there is the reassuring thought that checks and brakes will still exist in the form of the old-fashioned, uniquely human qualities like wisdom, common sense and, perhaps most old-fashioned of all, lovingkindness.
Death of a Whole Species: Extinction
So far, we have been looking at the individual cell or the individual living creature, but the idea of death applies also to the species. It is a fact that 99.9 per cent of all the species that ever existed are now extinct. Those alive today are the tips of the tiniest twigs of the tree of evolution. Only about one in every ten thousand species that ever lived are still around. Throughout life's history there have been one or two extinctions every week. In terms of its emotional impact the death of a species may be less disturbing than the death of an individual creature; but it is still death, on a larger and equally irreversible scale.
An extinction can take place quite quickly. When people think of an extinct species they often think of the dodo, a flightless bird about the size of a turkey that used to live on the island of Mauritius. Within a hundred years of their arrival (by about 1681), human settlers on the island had exterminated it. In 1810 another bird, the American passenger pigeon, existed in its millions. Migrating flocks darkened the skies and the weight of their numbers broke great branches from trees. As late as 1871, 136 million pigeons were concentrated in a single nesting area of 850 square miles in Wisconsin. Yet by the end of the century the species was rare, and the last individual died in Cincinnati Zoo in 1914. The International Council for Bird Preservation lists 108 species of birds, worldwide, as having become extinct since the year 1600 (the total number of bird species is about 9,000). Most of these extinctions have been caused by human activities. However, deaths of whole species have been a regular feature of evolution, essential for change and progress. At times, too, there have been mass extinctions, in which vast numbers of species have been wiped out. One such episode occurred at the end of the Cretaceous period, 66 million years ago, when the dinosaurs and much of marine life perished. One explanation is that an asteroid hit the earth, forming a global cloud of dust particles which blocked out light and heat from the sun, causing radical climatic change with which many species could not cope.
We appear now to be in the midst of another mass extinction, caused by our own actions. Thousands of species are dying out each year as humans destroy their habitats or kill them directly. Many species have been obliterated by human hunting. Maybe this is acceptable when it is done for food, as in the case of the giant birds called moas in New Zealand, hunted to extinction within a few hundred years by the Maoris; but doing it for fun is another matter. Elector John George II of Saxony, who reigned between 1656 and 1680, was crazy about hunting, and he shot an unbelievable total of 42,649 red deer. Luckily he did not extinguish the population. Today, we tend to make a fuss when larger, more familiar species are threatened with extinction; but countless less well-known ones are disappearing all the time. It is hard to absorb the fact that living species are now becoming extinct at 100–1,000 times the average rate in the geological past. On the other hand, very many are still with us. Around 1.5 million species are named and recorded (a disproportionate number of them beetles), and there are probably a few million more still not recognized and classified.
The answer to the threat of accelerating extinction rates, as humans swarm over the surface of the globe, their houses and food-growing areas displacing other creatures, is to maintain selected species in zoos. The last wild specimen of the European bison (also known as the wisent) died in 1925, but the species has been saved by breeding it in zoos. Maintaining species in zoos is not just preservation for the sake of it, or to satisfy mere curiosity: it enables study and provides for the education and delight of future generations.
CHAPTER 2
The Main Causes of Death
Anyone can stop a man's life, but no one his death; a thousand doors open on to it.
Marcus Seneca (4 BC–AD 65), Roman philosopher and poet
Until the nineteenth century the world's population stayed well below a thousand million, but since then it has increased at an alarming rate. By mid-1996 the total stood at 5,800 million, and it is increasing at 86 million a year (about 167 born every minute). By the year 2000, it is estimated, there will be 6,158 million of us; by 2025 8,300 million. Presumably the figure will soon be double what it is now. At present at least half of the world's population live in cities of more than a million people. There are 280 cities of this size, three times as many as in 1950, and all the new ones are in developing countries. Birth vastly outnumber deaths.
These are disturbing figures; but the future estimates are not uncontested. Some groups of experts say that the world population is unlkely to double in the twenty-first century, but instead will reach a peak around 2070–80 and then decline. They say, for instance, that fertility is already beginning to fall in many developing countries. Indeed, there are so many factors to take into account that all long-term predictions should be suspect. Most of the people who will be alive in 2020 have already been born, so we can take them into account and make reasonable calculations up to that time. But later in the next century? Will famines continue, will AIDS have been controlled, could new devastating infections appear, and, most important of all, are the elderly going to increase in number until we get near to the 'maximum' natural human life-span?
The Broad Picture
One of the attractions of studying birth and death is that, unlike health and happiness, they can easily be measured, counted. It is true that not everything that counts can be counted, but there is something to be said for knowing about numbers, knowing how often something occurs. For instance, being stung to death by a scorpion is an alarming thing to think about, but can be put into perspective by discovering that only 1,000 people a year worldwide die in this way, compared to 4 million a year who die as a result of of accidents and violence (a total in which automobile-related deaths loom large).
Death rates in developed countries (Europe, North America, Australia, New Zealand, Japan) have declined more or less continuously through the twentieth century. Before 1930 this was due for the most part to fewer deaths during infancy and childhood. By the early 1950s more than 94 per cent of newborn infants could expect to survive to adult life, and by the late 1980s 98–99 per cent. Now, nearly all of the 11 million deaths a year in developed countries are of adults. And the number of deaths is catching up with the number of births. In the UK deaths will exceed births from about the year 2024, at which time the population will have levelled off at about 60 million. The picture is different in developing, poorer countries in parts of Africa, South America and Asia. Here, infant and child mortality is still as high as it was in developed countries in earlier centuries. Most of these deaths are due to infectious and parasitic diseases, often coupled with malnutrition. But we have to make a distinction between the death rate, meaning the deaths per 100,000 population, and the total deaths in the population. For instance, nearly half of the total number of people dying with heart disease and stroke are in developing countries, but in the relation to population the rate per 100,000 people is higher in developed countries such as Finland, UK, New Zealand, Sweden and the USA.
(Continues...)
Excerpted from When We Die by Cedric Mims. Copyright © 1998 Cedric Mims. Excerpted by permission of St. Martin's Press.
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