When Father Alfonzo Aguilar, at that time still working in the Vatican in Rome, asked me to help him with a symposium and a follow up book on What is life?, my answer was, that there were already so many books about that, why not instead a symposium and a book on “What is death?”. Which he did. The corresponding book he edited (see below) contains a series of interesting articles on the definition of death, seen from the biological, the philosophical, the theological points of view. To many people, this project may sound strange, even absurd. What there is to say about death? Death is the end of life. What else? In fact, the question arises several issues - I will rapidly sketch some of them here.
First of all, there is the question of the criterion of death: when do you (the physician) may declare that the patient is dead? In particular, for long time the diagnosis of death was based on the absence of breath and pulse, and cardiac arrest protracted for at least twenty minutes. However, starting from the fifties of last century, a series of clinical techniques were introduced, which were able to maintain artificially certain vital functions – and it was at this point that a neurological criterion was deemed necessary, and was in fact introduced in the early 1990 (the Uniform Determination of Death Act in the States). To this point, we can say that there are basically two lines of procedure in the clinical literature for the diagnosis of death: the cardio-pulmonary criteria; and the neurological criteria, i.e., the brain-death diagnosis. Of course, death is a unitary phenomenon, and Paolo Rossi in the cited book recites that “death by cardiopulmonary arrest occurs when respiration and circulation have ceased for a time interval which is able to cause the irreversible loss of all cerebral functions including the brain-stem”.
But the brain-death, instead of clarifying the situation, introduced a big bioethical issue: the question of organ transplant. In fact, the brain-death diagnosis allows physicians to discontinue intensive life-save treatments and to perform organ transplant when the organs are still functioning. In that over mentioned meeting in Vatican organised by father Aguilar, I witnessed surprisingly fierce discussions, in which the physicians were put under the accusation of performing organ transplant when the patient was not dead yet - as the heart was still beating - the flat EEG (electroencephalogram) was just a medical excuse to cut the patient. Of course, from the historical and scientific point of view, this kind of accusation is out of place - but this debate gives an idea of the issues at stake - and the relevance of the question: when is a person really dead? Let us see this question from the perspective of the systems view of life.
For that, let us begin with the notion that life is an integrated system, in which all organs and tissues and functions are linked and interacting with each other. To simplify this, let us consider the figure 1, which shows only the main organs. The lines joining the various organs with each other are not due to the artist’ fantasy, but correspond to a physiological reality: the intestine cannot be seen as an independent, isolated unity, but must work in conjunction with the stomach, the liver, the spleen; and the heart cannot beat at an arbitrarily speed, it must coordinate and be in harmony with the other parts of the body. It is just like an orchestra playing a symphony: the musicians must be in tune with each other, no one can act independently. The orchestra is an integrated unity, and so is life. And the figure 3 shows the orchestra at the end of the symphony: the musicians do not interact, do not listen anymore to each other. The organs are still there, some of them can even be partly functional for a while, but they are now isolated from each other, they do not belong anymore to a functional whole.
Thus, let us consider a living horse, neighing and jumping; and close by a dead horse, one which just died, and which then has all DNA, all proteins, all blood, all tissues and organs… of the living one. So, if this second animal possesses everything, why do you call him dead? The bright student, to whom you ask this question, would answer showing the two figures above: the figure on the left represents the living horse, and the one of the right, the dead horse.
The systems view of life has been amply discussed in a recent book by Capra and Luisi (2014). An integrated system, one in which the different parts interact with each other to form a complete whole, is present also in a machine - be an automobile or a watch. What is then the difference between a living system, as we have in any organism, and a machine?
We can answer by looking at the behaviour of the simplest living unit, the cell. A cell, any cell, is the place where a myriad of chemical transformations take place, several thousand in each of our cells. Sugar which is burned, proteins and amylose which are hydrolysed, DNA and RNA which are continuously synthesised and broken down. But despite all these transformations, the cell maintains its own identity: a liver cell remains a liver cell. This apparent paradox is possible because the cell has an internal organization (call it metabolism) which permits the re-generation from within of all material which is being disposed of.
And what is true for a cell is true also for any larger organism: our body’ haemoglobin is destroyed every few days, but it is re-made from within the cell, and so is for all proteins, nucleic acids, polysaccharides. And so is for the apple tree, which loses the fruits and leaves in the winter, but re-males all of them, from within, in spring and summer. Thus, life is a factory which remakes itself (autopoiesis) from within. An automobile, a watch, cannot do that, and this is the profound difference between the living and the non-living. And life goes on until this process of self-maintenance via autopoiesis is possible. And it is then clear that this is possible thanks to nutrients and energy which come from the environment: each living system is a thermodynamically open system, should be seen as an open reactor with a flow of material/energy coming from the outside and waste materials which goes away.
Now, let us go back to our figure 3. The whole organism is dead, but each organ, once isolated and cut from the rest, may be considered living until the overall metabolism is possible because of nutrients which are still around. Eventually, also the organ dies, but the single cells may remain alive until they receive nutrients from the tissue environment. Then the cell metabolism stops and also the cell dies.
From all this is clear that death, seen from a systems point of view, is a process, a stepwise course of action: first the entire organism, then the organs, then the cells. Should we then wait, to pronounce the word “death”, until the last cell of the last body’ organ dies? Clinically, it would probably be too much, and also technically very difficult. So, let us settle on this: from a systems point of view, death is when we reach the situation depicted in the figure 1. This should correspond both to pulmonary-circulation death, as well as brain-death. As I mentioned, several other aspects of death are discussed in the afore cited book by Aguilar. Here I would like to add one, which concerns the drastically different view that science and religion have on human death.
For traditional science, when one person dies, nothing is left but matter, and the molecules and atoms of the corpse are recycled - and utilised for new forms of life. We have on our Earth the same atoms – with negligible addition from cosmic dust - than at the beginning of life, so that we have in our body atoms which have belonged to dinosaurs to Neanderthals to monkeys or turtles which lived millions of years ago… How fascinating would be, to reconstruct the history of each of our atoms in the body! But the point I wanted to make is that religions, instead, state that with the death of the individual something remains, or migrates, call it soul, or reincarnation. Death for religion is not the end of all. And from this, one may jump to the notion of immortality. Why should we all die? Well, this is true for mammals, actually for all multicellular organisms… but is it really true for all forms of life? Well, the earth, for the first two billions years, was inhabited by unicellular organisms, bacteria, which at a mature point of their life would divide up in two, and each of these two, in turn, would divide in two, and so on… The one becomes two, and no corpse is left behind. Isn’t that a form of immortality? I leave the answer to you.
And then what comes to mind is the perennial desire, or fixation, of mankind to live forever, or at least much much longer. But man is already one of the most longevity animal on earth, actually perhaps the one who lives the longest. There is the fear of death, of living too little, that death may deprive you of something. But as the poet says (in this case Wislava Szymborska, Polish poetry nobelist (1996) this is not true:
Is always too late by that moment
To no avail she shakes the handle
Of that invisible door.
To nobody can she steel away
The time that has been lived.
Alfonso Aguilar (ed.) What is Death? Ateneo Pontificio Regina Apostolorum, Roma, 2009
F. Capra and P.L. Luisi, The systems view of life - a unifying vision, Cambridge University Press, 2014
P.L. Luisi, The Emergence of Life, 2.nd edition, Cambridge University Press, 2016
W. Szymborska, Poems new and collected, Harcourts, 1998; the cited poem is my English translation from the Italian edition W. Szymborska, Gente sul Ponte, Scheiwiler, Milano 2007.