The Romeo Error

by Lyall Watson

  Ask most biologists to define death and you learn that it is an absence of life." Ask for a definition of life and you get almost as many answers as there are practicing biologists, but despite the fact that life arose from nonliving matter, very few of the descriptions will be framed in the negative terms that are applied to death. This is strange, because in the cosmos death is the state of equilibrium, the natural condition to which all life tends if nothing from outside is added to maintain it in action. The Greek and German words for life express this quality more precisely than the English by giving the sense of "remaining" or "persisting." Life has been well described as the adhesive property, and logically it is the state that deserves to be defined negatively, as "an absence of death."

  We have a bias toward life. In an evolutionary sense this prejudice is good and useful, it has survival value, but it does not help us to understand the intricate relationship that exists between life and death. It makes death very difficult to examine objectively. One psychologist describes his research into death as ending all too often with the realization that "I have simply observed my mind as it scurries about in the dark." [142]

  Perhaps the best way to come to scientific grips with death is to take biology, still protesting that it is the science of life, back to consider life at its most simple, to look at life when it is still in doubt, when there is little to distinguish living from nonliving.

  Molecular biologists today have access to more and more sophisticated electronic aids to vision, and with each increase in magnification, it becomes clear that there is in principle no ultimate gap between living and dead matter. As the structure and behavior of molecules come to light, it seems that living organisms can best be described as nonliving matter that has become organized in a special and different way. Studies which are now beginning to focus on this difference show that it is largely a matter of degree and that all possible stages of organization intermediate between what we consider "dead" and what we define as "living" are present in nature. It is impossible to draw a line anywhere along the spectrum and say "life begins here."

  The material in which life becomes organized is organic matter. It is composed of carbon compounds. Of all the more than one hundred elements now known, carbon is unique in that it can combine with itself to form very large conglomerations of thousands of atoms, called macromolecules. The most common of these are proteins, which make up about half the dry weight of any living organism. Man has over 100,000 different kinds of protein in his body, but he is nothing special in this respect. Proteins form the stuff of all life. In organisms as different as cabbages and kings, almost identical proteins get together to control the speed of chemical reactions and to act as controllers of all growth processes; and these proteins are all formed under the watchful eye of one small group of related macromolecules that carry the plan of organization from one generation to another. Living things, no matter how much they may differ from each other in appearance and behavior, are identical at a fundamental level. They came to life in the same way, and they depend on the same chemical processes for maintaining an independent existence and for reproducing themselves.

  There is also a limiting factor common to all life. To carry out these fundamental activities, a large number of giant molecules are necessary, and all of these have to be accommodated within the same container. So a certain minimum space is required, and this lower limit to the physical size of any independent living organism has been calculated to be about five thousand angstrom units in diameter, [48] which means that twenty thousand such structures could fit side by side across the width of a fingernail. This limitation suggests that we could begin to define death as anything smaller than five thousand angstrom, but hovering uncertainly in the lower regions of the death-life continuum are a number of entities that range from one half to one fiftieth of this critical size and yet still show many of the characteristics of life. These awkward nonconformists are the viruses, and they hold some vital clues to a realistic assessment of death.

  Viruses reproduce themselves, but to do so they have to make good their chemical deficits by invading the cell of a more conventional organism. Here they take over the biological assembly lines and divert them from making the normal substances of the host cell to producing new viruses. It has been argued that this dependence on other life means that no virus can be considered a living organism in its own right but, with the exception of green plants, there are very few living things that do not feed directly on other forms of life. The viruses cannot be disqualified on this count.

  The ability to reproduce themselves under any circumstances makes viruses more lifelike than the red cells in our blood. A pinprick drop of blood swarms with five million cells that contain hemoglobin and convey oxygen from the lungs to the rest of the body, but during their development they have lost their nuclei and are therefore completely incapable of reproduction. This does not mean that they are dead. Mules and sterile men are not condemned to death simply because they cannot reproduce. There are obviously degrees of deadness, and the red blood cells are considered to be more alive than dead because of their complex internal integration. They have become organized in that vital "special and different way."

  In 1935 Wendell Stanley at the Rockefeller Institute (now Rockefeller University) in New York discovered that it was possible to concentrate the juice from infected tobacco plants and to isolate the tobacco mosaic virus in a crystalline form. [129] The crystals of this particular virus are long and thin and apparently indistinguishable from the crystals of purely chemical compounds. They can be crumpled and powdered and kept in a glass tube like any other inert organic substance, such as powdered sugar. Both virus and sugar crystals can be made to grow again. If the virus powder is inoculated into growing tobacco plants, it goes immediately into solution and starts to prey upon the cells of the leaves and to produce more virus. The sugar powder needs a different kind of treatment. A concentrated solution of sugar has to be made and to be kept at a special temperature. Then this solution has to be either seeded with a sugar crystal or left long enough to itself for molecules to accumulate into a structure of the right shape. This structure then increases in size and splits in certain ways until two identical crystals are formed. In both cases reproduction has taken place, but there is a critical difference in the way that this has been organized.

  Most organic substances do not readily form crystals, but will do so in a pure and highly concentrated solution. A crystal can usually be formed only from identical molecules (hence the need for purity), which become attracted to each other and arrange themselves to form a regular and repetitive pattern. This is how both virus and sugar crystals were formed in the first place. Once each has been powdered and destroyed, the sugar can only be brought back to the crystal state by diluting it and then applying heat to bring it back to the critical concentration. When the process is complete, there is no more than the original amount of sugar, but when the virus powder is diluted in a host cell, it starts off a biochemical reaction which not only releases heat but results in an enormous multiplication of virus material.

  The sugar is involved in a closed thermostatic chemical reaction. The virus induces an open thermodynamic process in which there is an exchange of matter with the surroundings. This is the vital difference between living organisms and nonliving organic matter. Both obey the same fundamental physico-chemical laws, but they differ widely in the way that these apply to them. Living matter is organized in such a way that it draws on energy in its environment to maintain its order. Nonliving matter simply becomes disorganized.

  If the subject of crystals seems remote from biology and our concern with life and death, just look at the back of your hand. The surface skin cells are all translucent crystals attached to one another by thin films of oil. These cells are hard and filled with keratin and by most definitions are dead. Very soon they will be sloughed off and disappear along with the other 500,000 million cells we lose each day, but while they last, they lie
over the surface of the whole body like a plastic suit of armor designed specifically to protect the delicate tissues beneath. Truly living cells cannot survive exposure to the air, but the protective crystal cells are not killed by being forced to the surface by replacement from below. They commit suicide. Long before the cells reach the outside air, they begin to produce fibrous keratin until the whole cell body is filled with the horny substance. Technically these cells are dead. They certainly cannot reproduce themselves, but they equally certainly consist of matter that is highly organized and that is arranged at a special place at a particular time.

  Are the skin cells dead? If so, our bodies are literally covered with death. There is not a living cell in sight, and yet our friends, who see nothing but death, persist in regarding you as alive. Let us give them the benefit of the doubt, because it is becoming clear that there are varying degrees of death. It seems that the most realistic classification of living matter will turn out to be one that relies on a combination of both life and death. The one thing That the strange behavior of viruses demonstrates beyond a shadow of a doubt is that the old polar definitions are totally inadequate.

  Life depends on death. We owe our lives not only to the cells that erect a barrier between us and the outside world but also to armies of others that regularly lay down their lives in internal battles dedicated to the greater glory of the organism.

  For every thousand red cells in our blood, there is a slightly larger, more transparent one with a nucleus. This white cell has the power of amoeboid movement and tends to creep with others of its kind along the walls of the blood vessels instead of being bowled along down the middle in the plasmic tide that carries the red cells to their appointed places. White cells use the bloodstream only as a means of transport and ooze out through the walls of capillary vessels to any point in the surrounding tissues where they may be needed. White cells are ready for instant action. They congregate rapidly at a site of infection or injury and advance on intruding bacteria, taking them captive by flowing completely around the invaders. As many as twenty bacteria can be imprisoned and eventually digested within a single cell, but the battle is by no means one-sided. The corpuscles often die from the effects of bacterial toxins, and the pus that appears at the site of the conflict is simply an accumulation of dead white blood cells. Our bodies obviously need these omnivorous warriors, who not only cope with the constant threat of bacterial invasion but also absorb particles of pollution in the lungs, dissolve splinters, and generally attack anything foreign to the system. To have too few white cells would be disastrous, but the democracy of the organism can be equally seriously threatened by an army that becomes too large. An overproduction of white cells produces leukemia.

  Under normal circumstances a balance is maintained. The body avoids a harmful population explosion by making new cells at the same rate as the old ones die. It does not have to wait until they die, because their deaths have been largely predetermined. Each day part of the body dies in order that the rest might live. The deaths that do occur are clearly not due to chance or to a random competitive process involving only the survival of the fittest. They are directed toward a particular end. Death is programmed into life, and living organisms cannot survive unless the death of certain of their parts occurs on schedule.

  Two embryologists in the United States demonstrated this fact very elegantly in a recent experiment with developing chicks. [239] They showed that the wings of fowl could never be functional unless specific mesodermal cells in the wing bud of the embryo died at an appropriate time and allowed others to develop into flight muscles. The death of these cells is an intrinsic part of the growth program in all flying birds. A similar pattern of built-in obsolescence is apparent in the development of the frog. Tadpoles live in water where they feed on aquatic plants and move about by undulations of a long muscular tail. As they develop, their diet changes to include slugs and worms, and gradually they move closer and closer to the shore where there is a wider variety of insect food. Legs appear, and at about fourteen weeks of age, the young frogs make their way out onto dry land where their tails act only as an impediment. At this point of development, the tail gradually disappears -- it is digested from within by special mobile cells that behave exactly like the white blood cells that attack bacteria, except that they are cannibalistic. Life proceeds by killing itself.

  These are examples of death reinforcing life within a single organism. A much more familiar process is the way in which death maintains a necessary balance by preventing total population growth from getting out of hand. If death did not exist, the fastest breeders would take over the world. One invisible little bacterium could on its own produce a mass equal to the weight of a man in a few hours -- and every ounce of soil contains a hundred million such potential patriarchs. In less than two days, the entire surface of the earth would be covered in great smelly dunes of prettily colored bacteria. Left similarly unhindered, a protozoan could achieve the same end in forty days; a housefly would need four years; a rat eight years; a clover plant eleven years; and it would take almost a century for us to be overwhelmed by elephants. [161]

  Fortunately, the growth of population in many species is self-limiting. In the classic case of botanical succession, a pioneer plant that thrives on soil with a low nitrogen content moves into an open area. Here it grows abundantly; as it does so it adds nitrogen to the soil, and by virtue of its own success it destroys the very conditions that made that success possible. For species without this kind of self-control, there are predators waiting to take their toll.

  Life feeds on life, and this produces a cyclical effect in which the atoms that make up a particular piece of living matter may find themselves going on endlessly from one living form to another. Green plants produce life from soil, water, and the energy of the sun. They may draw their raw materials directly from nonliving matter, but then the plant is eaten by a caterpillar, who gets picked off by a passing sparrow, which falls prey to a hawk, which dies of frostbite and is consumed by scavenging beetles . . . and so on. Once caught up in the network of living matter, atoms tend to find themselves trapped there by a sort of organic momentum that carries them through countless life cycles that may last for hundreds of years. It almost seems as though life is capable of adding some mystical property to nonliving matter simply by coming into contact with it and that, once incorporated into a living cell, matter is changed in a way that makes it more likely to be incorporated once again. We shall see later that it is even becoming possible to measure this change.

  Biophysicist Joseph Hoffman calls this continuing process the "atomic vortex of life" and points out that there are few foods we eat that have not recently been part of another living thing and that the growth of plants is enhanced by the presence of former living material, even when (like wood ash) this has been incinerated since it was last alive. [121] The change induced by life in matter is partly a chemical one, brought about by the transformation of inert amino acids from their normal D (or right-handed) form to a structural mirror-image known as the L (or left-handed) form. The L form is unique to living matter and starts to revert to the more stable D form as soon as it is shed by a plant or animal. This process is so universal that it is possible, by measuring the proportion of D and L in a sample, to estimate how long it has been dead.

  Once again we are confronted with the notion of degrees of death. The remains of living organisms still contain traces of life and should perhaps be considered as part of life. Every single piece of organic material now found on earth's surface was formed by life, and many fragments seem to carry traces of this experience. By all traditional definitions; humus is dead, and yet it is considerably different from the rocks on which it lies. Hoffman suggests that "living things know more than they can tell" and that a tree puts out seeds "in the faith" that there will be more there to receive them than just barren rock. In the light of the connections that we now know exist between isolated plants and other living matter, it is difficult not to
agree with him that the net of life should be cast wide enough even to include everything recently "dead."

  At the interface between organic and inorganic matter are the highly versatile bacteria which are unquestionably alive. A few are photosynthetic and receive their energy like plants direct from sunlight, but the rest require organic food. To get this they foster the process of decay in which complex organic compounds are broken down or mineralized into simpler inorganic chemicals. The bacterium takes what it needs and the rest is released into nature. Many of these products do not occur spontaneously, and if bacteria did not make them available, they would be locked away forever in forms inaccessible to other living things and all life would soon disappear.

  Bacteria themselves seem to be virtually immortal. After growing to an optimal size, which may take only twenty minutes, they simply divide and then the two new bacteria feed and grow and then divide again. Under ideal conditions in which no bacteria are killed by viruses or white blood cells, none would ever die. For a bacterium there is no death from old age and no corpse except when it is actively destroyed. So for the most simple collections of living matter to be enclosed within a single cell, death is a meaningless construct. Evolution seems to have moved from totally dead inorganic matter to everlasting self-replicating life in one swift step. The complication of a flexible life-death relationship appears to have been a refinement that was added later.