Biology 103
2003 Second Paper
On Serendip

Efficiency Above All: A Biological Look at Suicide

"And let me ask you this; the dead,
where aren't they?"
– Franz Wright, New Yorker Magazine, Oct. 6, 2003

"Dear Mom and Dad," the letter begins benignly, "Thank you for all of your commitment. But I am not a suitable daughter, and you will all be better off without me. Please realize I have done this for your own good." Nothing more. And beside it, Mr. and Mrs. A find their daughter, dead by her own hand.

So begin the episodes of anguished soul-searching, of horrific "if-onlys" experienced by the family members of countless suicides. Anyone who has faced what Mr. and Mrs. A now grapple with knows that the girl is wrong: they will not be better off, not feel happier, without her. Yet each year, thousands of suicide victims express similar convictions: I am killing myself, they reassure us, for your own good. This thinking – this appeal for selflessness that our society cannot condone – where does it come from? Why, in truth, do people kill themselves?

The problem of suicide ravages the minds of its survivors – of philosophers – and, more recently, of psychologists. We simply cannot understand it. Why suicide? While many non-biological scientists are inclined to define suicide as a conscious act – thereby excluding, perhaps, all non-human self-inflicted deaths (1), (2) – lets us stick with the more basic definition of suicide as self-murder, with or without cognitive "knowledge" or "intent" (***). And, as the concerned psychologists plunge on in their direction, let us examine this problem from a different standpoint, that of biology. In order to make sense of the biology of suicide, however, we must first understand the more general omnipresent phenomenon: death.

All life has a catch: it ends. No living thing can escape death. Not only do people, animals and plants die, the components of living systems also die independently from their hosts, and continually (3). It begins in the fetus, whose extra, formative cells – like the webbing between the fingers and toes – die at a certain stage in development (4), (5). But cells also die by the trillions in the stretch between birth and death. In fact, every cell in the human body (except select nerve cells) will reproduce and die at least once during the human lifetime (4). Some cells, such as skin cells, die daily; we live beneath a protective layer entirely composed of dead skin cells (6). Truly, death exists all around us, upon us, within us. There is no escape.

But why – why death? Well, this mysterious force that we fear above all else works to keep life in balance. If living things did not die, but new things were born, then life would accumulate until it ran out of space and resources and could not survive. And if new life were not born – if reproduction did not exist – then life could not grow and change and increase in diversity. Life would be stagnant, and this WOULD NOT BE LIFE as we call it. For this reason, both reproduction and death are integral to the maintenance of life (7); life could not exist without death! Moreover, the natural selection inherent in the process of evolution requires poorly-adapted organisms to die off and turn over resources to the better-adapted. Yet even disregarding natural selection, death is necessary to allow for birth, which allows for increasing variation, and, thus, life.

It's all very well evolutionarily to die of old age or when your functions cease to be needed. But what about murder? Why must that take place? Though many of us accept death-by-old-age as "natural," we view murder as horrific, barbaric, most decidedly unnatural. And yet it isn't! If incurably sick organisms were left to die slow, natural deaths, the landscape of life on our planet would deteriorate just as an organism would languish and die if all of its old, slow-functioning cells were left intact, consuming resources at minimal output. As a body cannot be healthy when composed of old, sick, slowly dying cells, so a community cannot be healthy if made of weak, sick individuals (6). When a member of the whole starts to require more resources to survive than it produces in return, that's it – it's out of the game. Thus murder exists for those cases of slow undoing in which it would simply be impractical, uneconomical, to await death.

So perhaps we can condone murder, then, if we must – for the greater good. Perhaps it is all right that killer T-cells, a kind of lymphocyte, kill body cells infected with viruses (6); perhaps, even, we can admit to some rationale behind performing the death penalty or removing a person from life support. Whether to conserve resources, to curtail irredeemable suffering or to prevent future damage, the prevailing idea driving these murders is the same: It's not worth letting this one live any longer. Better to be done with him now.

Understanding the ubiquity of, indeed, the indispensability of death – old-age and murder alike – belies any perception of death as "unnatural" or "pathological." Seeing death as a part of the repeating, expanding cycle of life allows many mature people to reach some acceptance of this reality. But it is still not so with suicides. Crying out with a terror as intense as though the phenomenon were entirely new to them, most people label the self-murder of a human being a unique and wholly useless source of grief. But is suicide really unnatural? Is self-destruction unique to the human organism? Is it functionally useless? The answer to these questions is: No.

Like all of death, self-destruction is ubiquitous, occurring on many levels – cell (3), organ, human, animal, plant – and, like all of death, self-destruction is a vital component in the survival of life on earth. (4) The purpose of all death, regardless of its form (and including suicide), is to promote the survival of life elsewhere. Most directly, cells and organisms unsuited to cope with some aspect of their environments die so that similar cells and organisms, who are competing with them for space and resources (i.e. food), can get what they need to survive. It is a matter of investing energy and resources in the members who will contribute the most to the overall community – whether the community is the collection of cells in a living tissue or organism, the organisms in a clan or society, or even the whole of life on earth. An exercise in Utilitarianism, in sacrificing the lost sheep for the herd. And so antelopes killed by lions yield their places to other antelopes with the skills to escape the lions. Old people, and old cells, die once their systems have atrophied a certain amount so they will longer consume time, energy, resources needed by the more efficient bodies of their children, or children cells. Children who die of cancer sacrifice the resources afforded them to other children with the strength to survive (or altogether escape) the blow of cancer. Nerve cells in a developing fetus who cannot hook up properly to one another will die, leaving the job to those remaining neurons that can (6). (It is "survival of the fittest," as Herbert Spencer said, both for organisms and for cells!!) In all of these instances of self-sacrifice, death by self-destruction forms no exception. Lymphocytes, white warrior blood cells in animals' immune systems, self-destruct if they cannot kill invading pathogens so that the resources needed to create and sustain these lymphocytes go only to those fighters who can vanquish their enemies (6). On the macro-level, female octopi starve themselves to death after the birth of their offspring so their children will not have to share resources with them (1). Some lemmings, though their case is hotly disputed, probably walk off of precipices when their community gets too densely populated, so as to thin it out to a healthy number (2). In suicide, as in all death, the movement toward the greater good prevails.

Is suicide necessary? Could it be effectively replaced by the somewhat less humanly-objectionable phenomenon of murder? To answer this, imagine a community of ants, one of the most complex governmental systems visible within the two-square-foot window of the human eye. Within this little six-legged community are many hard-working members well-suited to their job in Antville. But Antville also possesses a significant contingent – perhaps 20% of its members – who wander aimlessly hither and thither, entirely maladapted to life as an ant, unsuited to do anything but gawk. Now, your job as the divine power stretching over Antville is to find and murder the deficient ants. If you do not, they will bump into the well-adapted ants, throw them off course, eat their food, and eventually cause the death – and downfall – of all of Antville! Quick, quick, find the deficients and eliminate them! The future of Antville depends on it!

Granted, this analogy is not quite accurate. Unlike a lymphocyte, you are not programmed specifically for spotting and killing misfits. And yet ... with so many poorly-suited ants, and more being born all the time, wouldn't it be easier if they could finish themselves off? What if the ants were endowed with inner machinery that caused them to self-destruct if they were not well-matched to their environments? Then you would get a break, and you'd be able to focus on protecting your ant community from invaders. The lymphocytes would get a break, and they'd be able to focus on fighting off viral and bacterial infections and demolishing (hopefully) invasive cancer cells (5), (6).

And so it is that many cells, rather than depending on other killer-cells, commit suicide on command. But this command, rather than coming from some overarching divine power, originates within. Cells contain the command for suicidal actions – the spouting of digestive juices from lysosomes, the rupture of membranes – within their all-important little control centers, the DNA of their nuclei. An encoded, preordained message for self-inflicted death (6). Many cells will self-destruct only under certain, specific circumstances, i.e., if glucose or water runs out. The suicide command gorged within the genetic material takes effect only in response to certain molecular triggers (like lack of glucose) (8), (4). But other cells, like the skin or plant leaves, are born to die of their own "hand" (8).

Suicide is NOT absolutely NECESSARY for life to exist – after all, cells might kill each other off, instead, as might other organisms (murder is always a possibility) – but suicide is highly practical due to its extreme EFFICIENCY. Suicide is more efficient, more economical, than both murder and death by gradual malfunction and breakdown (See CHART below). Just as the panoptic prisons of the 19th century took advantage of prisoners' innate abilities to psychically imprison themselves, thereby freeing up the wardens (9), biological systems profit from cells' abilities – indeed, predispositions – to self-destruct and liberate the cells that would otherwise be belabored with their murder. (In truth, cellular murder and suicide are not necessarily mutually exclusive. Cells in the process of self-destruction may be consumed mid-suicide by macrophages, other cells inclined to "eat" those surrounding them. Even cells that complete the process of self-murder are generally finished off by macrophages (4), (10).)

Does biology also profit from higher organisms' abilities to kill themselves? Does suicide among conscious beings – specifically, people – also originate from this drive of all things biological to conserve energy, time, and resources? Do the "natural laws" that govern suicide on micro-levels also apply on the macro-level? I shall not attempt to answer these questions. Ethics, at the crux of all human endeavors, stands in my way. For me to call suicide victims poorly-adapted and burdens to their environment would be insensitive at best, maybe cruel. And I can think of no other way to approach this delicate topic.

To fully unravel the enigma of human suicide in the light of biology will require great tact and even greater courage, courage to transgress fuzzy ethical boundaries (or the creativity to sidestep them!) in the hopes of encountering new insights. We have much to learn. Inquiry into this area should take the shape of comparison studies between cells, non-conscious organism (such as plants), animals, and human beings. Whatever sub-cellular interactions take place within the suicidal cell should then be screened for, on the macro (inter-cellular, hormonal) level, inside the bodies of suicidal organisms. Rather than focusing on consciousness – that sticky topic with no biological code and no parallels across the spectrum of organisms – scientists ought to pay attention to physiology. What physiological phenomena occur within the cell before it self-destructs, and do comparable phenomena occur in organisms? In people, even? A practical problem to overcome involves predicting when a cell or person is going to commit suicide; you cannot make accurate observations after death, as biological systems cease functioning then. But in uncovering the command for suicide within a cell's nuclear DNA (6), biologists are on the right path to determining which cells will kill themselves when. Then, when we can finally extend that knowledge to human beings, we will be able to understand suicide in a non-emotional, non-ambiguous, mechanical way. We may be able to predict suicides, assess their functions, and even, if we deem it necessary, prevent them.

The as-of-yet unbridgeable chasm between cellular self-destruction and human suicide is consciousness. Though we may never fully understand it, we cannot, despite my suggestions for rigorous objectivity, dismiss this unique quality. It is consciousness that makes us different (***). If nothing else, however, we may concede that it is interesting that the last conscious thought conveyed by many suicide victims – the selfless notion that "You will be better off without me" – precisely matches the non-conscious, evolutionarily-developed "intent" of cells that self-destruct to benefit their neighbors.

CHART: SOURCES OF INEFFICIENCY IN DEATH

Death By Old Age:
Long Time Required – YES
Other Agent Required – NO
Total Sources of Inefficiency – ONE

Death By Homicide:
Long Time Required – NO
Other Agent Required – YES
Total Sources of Inefficiency – ONE

Death by Suicide:
Long Time Required – NO
Other Agent Required – NO
Total Sources of Inefficiency - NONE
This simple chart compares sources of inefficiency in death by old age (gradual deterioration), murder and suicide. Note that suicide is the most efficient in terms of energy and resources being returned to the greater community. (Bear in mind also that old age, homicide and suicide are not always mutually exclusive.)

(***) An interesting afterthought: if we remove the conscious aspect of suicide, is there any real way to distinguish between self-destruction and death by old age? A cell that commits suicide dies quickly (with no external intervention); a cell that dies of old age dies slowly (with no external intervention). Both deaths occur to eliminate a now-useless cell. Wherein lies the time cutoff? And if we reduce human consciousness to mere brain behavior, is self-murder (initiated by the brain) any different from death by age and malfunction (initiated by, say, the heart or the liver)? In both cases, some part of the person's body dictates that the time has come for his life to end. Without the phenomenon of consciousness, only two kinds of death exist – death with, and death without, external intervention ("homicide"). Consciousness really DOES make all the difference ... !

References

1)Do Octopuses Commit Suicide?, subjective philosophical ruminations on suicide, octopi, and other animals

2)Jamison, Kay R. Night Falls Fast: Understanding Suicide. Knopf: New York, 1999.

3) Encyclopedia Britannica Article – Apoptosis, a definition of the mechanism of cellular suicide called apoptosis

4)Suicidal Cells, An Appetite For Self-Destruction – Animals, a good description of self-destruction of animal cells

5)Researchers Solve Killer Protein's "Crime", a discussion of cancer as a failure in normal programmed cell death

6)Clark, William R. Sex and the Origins of Death. Oxford University Press: New York, 1996.

6-b)Sex and the Origins of Death – A Book Review, a one-page review of the above book, from which I draw much of the information in this paper

7)Sex and Death: The Awful Existential Significance of Cellular Suicide, subjective ponderings on the interrelatedness of sexual reproduction and death, with some information on cancer as well

8) Suicidal Cells, An Appetite For Self-Destruction – Plants, a good description of self-destruction of cells, this time in plants

9)Foucault , Michael. Discipline and Punish: The Birth of the Prison. Random House: New York, 1977.

10) Weizmann Institute of Science: Death of a Cell, a discussion of one series of studies of cellular apoptosis

NOT CITED IN TEXT

11) http://www.sciencedaily.com/releases/1997/07/970722090258.htm>Stopping "Cellular Suicide" Could Boost Production in Biotech Labs, a look at some of the cons of cellular suicide in terms of technology

12)Researchers Find New Way to Trigger Self-Destruction of Certain Cancer Cells, a scheme for putting cellular suicide to use for humans!


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