Timeby Eva Hoffman
Novelist, cultural commentator, memoirist, and historian Eva Hoffman examines our ever-changing perception of time in this inspired addition to the BIG IDEAS/small books series
Time has always been the great given, the element that establishes the governing facts of human fate that cannot be circumvented, deconstructed, or wished away. But these days we/b>… See more details below
Novelist, cultural commentator, memoirist, and historian Eva Hoffman examines our ever-changing perception of time in this inspired addition to the BIG IDEAS/small books series
Time has always been the great given, the element that establishes the governing facts of human fate that cannot be circumvented, deconstructed, or wished away. But these days we are tampering with time in ways that affect how we live, the textures of our experience, and our very sense of what it is to be human. What is the nature of time in our time? Why is it that even as we live longer than ever before, we feel that we have ever less of this basic good? What effects do the hyperfast technologies--computers, video games, instant communications--have on our inner lives and even our bodies? And as we examine biology and mind on evermore microscopic levels, what are we learning about the process and parameters of human time? Hoffman regards our relationship to time--from jet lag to aging, sleep to cryogenic freezing--in this broad, eye-opening meditation on life’s essential medium and its contemporary challenges.
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By Eva Hoffman
PicadorCopyright © 2009 Eva Hoffman
All rights reserved.
TIME AND THE BODY
Is there such a thing as specifically "human time," and if so, what is it? Perhaps it is possible to delineate a very broad framework for human temporality by noting what it most obviously is not. The human mind is capable of conceiving, and even measuring, scales and dimensions of time which clearly do not belong to the sphere of human or even earthly possibilities. We can calculate — even if we cannot exactly imagine — intergalactic aeons and the speed of light; we can catch light from extinguished stars whose radiance has taken thousands of light-years to reach us, and we can capture sub-microscopic fractions of seconds which we have no way to experience.
It is surely a remarkable feature of the human mind that it can imagine such vastnesses and infinitesimal smallness; but these extremities do not belong to the temporal scale of our own experience. That scale is defined by some basic factors which so far have been unchangeable: the fact that we are organic, and have a particular biological make-up, and the equally determining fact that we live in this particular corner of the cosmos, and on this particular planet — our own familiar earth.
Before being human, we are living creatures, and this creates the first temporal condition of our existence. In the cosmic spaces, time "in itself" can apparently move in various directions, including backwards. But for us it moves in only one direction: from the past to the present, from growth to decay, and from birth to death. This, reassuringly enough, may itself have good cosmological reasons. In A Brief History of Time, Stephen Hawking speculates that "complicated organisms" like ourselves can exist only in a particular kind of universe — one which happens to be very much like ours. In other words, we are adapted to our universe — or the universe to us — in what Hawking calls the "strong version" of the "anthropic principle." One of the adaptations is to the direction of time. The universe we are in works on the principle of entropy, or the movement from order to disorder, and from initial mass to expansion and decay. This is why, in our kind of universe, in Hawking's view, the "psychological arrow of time" is pointed in the same direction as the cosmological and the thermodynamic arrow of time (the order in which entropy increases): from the past to the future. Intelligent life, Hawking posits — that is, the kind of life which would have a perception of "past" and "future"— is possible only in a universe in which the arrow of time moves in this direction. In addition, as many cosmologists have noted, by the standards of intergalactic spaces, conditions on our own planet are characterised by a highly exceptional moderation (at least, moderation by our standards). The earth is, comparatively, temperate in size, temperature and, indeed, temporality — that is, the length of its revolutions around the sun, and therefore its days and nights.
It is the length of that daily cycle which is the first terrestrial determinant of human temporality, as it is of other living creatures'. Whether Hawking's hypothesis about life's adaptation to our corner of the universe proves to be true or not, recent studies have made it clear that we are, on the biological level, quite precisely adjusted to the specific rhythms and cycles of the earth.
In the last few decades, problems of biological time have given rise to a new scientific discipline called chronobiology, within which various features of temporal behaviour are investigated through increasingly microscopic observations and precise measurements. One of the fundamental findings to emerge from these studies is that, within their appointed lifespan — and, so to speak, lifestyle — all biological species living on planet earth are adapted to earthly time, and its day/night cycle. This is one of those facts that can be taken for granted, or that can strike us as quite wondrous. For, whether animals are diurnal or nocturnal, their behavioural patterns follow, with some small adjustments, the twenty-four-hour cycle (as we have come to measure it). Moreover, the adjustment to the diurnal cycle does not occur through anything as simple as sight, which would let an animal know if it is day or night, or through any other sensory signals from the environment. Rather, the periodicity of living creatures is governed endogenously, from within, by versions of a marvellous mechanism called the "biological clock."
The facts which have been unearthed about these biological devices, and the seeming ability of non-percipient creatures to "tell time," are endlessly fascinating. There is, for example, the famous dance of the bees, through which bees returning from feeding tell their fellow workers in their dark hive where the nectar is located. They do so by dint of performing a series of movements called "waggles," which specify distances of the feeding site from the hive, the directional coordinates and the best time, in relation to the position of the sun, to arrive. And the bees do arrive, with uncanny accuracy, at the optimal time for the nectar to be collected.
How this happens, how biological clocks are constructed and the intricate processes involved in their operations, are still a matter of scientific speculation and research. However, while the actual biorhythms vary widely from species to species (some sleep most of the time; some hunt at night), it seems that the principles on which biological clocks operate are remarkably similar throughout the animal spectrum, suggesting that they have evolved from a single initial mechanism, or genetic code, rather than through convergent evolution. Internal clocks are among the oldest features of living organisms, to be found even in the most primitive bacteria.
Moreover, while the rhythms established by the biological clocks vary widely among species, it is another wondrous fact that in all species, and at every scale of organic functioning — genetic, metabolic, behavioural — these internal pacemakers work on the same basic principle, that of oscillation. This is a kind of movement which, like the swinging pendulum, advances along a certain path only to be restrained and pushed back in the opposite direction. For example, the rate of metabolism and bodily temperature oscillates regularly in many species, falling to a certain level before an internal feedback mechanism tells it to start climbing again. (Parenthetically, it is interesting to note that oscillation is the basic method of measuring time in man-made clocks as well; without the principle of regular motion, a division into regular units, both external and internal time would be an indiscriminate flow.)
The motion of oscillation, then, introduces temporality in living organisms, and is its basic pulse, or measure. Indeed, it can perhaps be said that internal temporal organisation is a fundamental requirement, as well as symptom, of life. Trying to answer the question posed by the physicist Erwin Schrödinger, which was simply "What is life?," a mathematician, Jonathan D. H. Smith, posits that "biological systems" are "systems complex enough to isolate their component space-times" — in other words, to structure the indeterminate flow of time and space through internal dynamics. Organisms are highly organised forms, and the internal structuring of time through regular motion seems to be among the earliest and most universal features of organic life. This, in fact, corresponds to what we actually know through simple observation: living organisms are entities which move of their own accord, while inanimate matter moves only under the application of external force. The measurement of organic time through oscillation also echoes philosophical intuitions dating back to Aristotle, who thought that time is the measure of motion ("the numeration of continuous movement").
But while movement seems to be a basic index of life, the Buddhists, in their contemplative quest for serenity, may also be expressing a physiological wisdom — for it seems to be a tendency of all organisms to seek homeostasis, or a state of balance. This is one effect of introducing negative feedback into the oscillations, and not allowing the motion to progress too far in one direction. For example, if an animal's temperature rises too much, reverse hormonal or metabolic processes kick in to cool things down.
The internal motions of oscillation have their unique pace in each species, and in each the pacing is coordinated at various levels of functioning — genetic, metabolic and circadian. In higher animals this happens through intricate feedback mechanisms, so that, for example, hormones and neurons work in concert, producing regular behaviours through the diurnal cycle. In mammals the main "clock" determining temporal behaviour has been found in a small cluster of paired cells located within the hypothalamus area of the brain known as the suprachiasmatic nuclei. (Interestingly, this is exactly the spot to which Buddhists point as the focus of contemplation, and which they call the "third eye," because it is supposed to open in a state of enlightenment.) Aside from this central mechanism, mammalian rhythmic patterns are encoded in a number of genes — including the per or "periodic" gene — working in complex interactions with each other and transmitting their information not only into the brain, but throughout the organism.
Moreover, there seem to be correlations not only among various internal processes, but between different scales of species' temporality. In mammals, for example, the rate of heartbeat seems to be inversely proportional to lifespan. Elephants live seven times longer than mice, and an elephant's heartbeat is seven times slower than a mouse's. Does that mean that mice, within their brief span of days, "feel" that they live as long — that they have the same amount of "experience" — as elephants? Is the perception of experiential quantities related to the speed of internal processes? As far as mice and elephants are concerned, we will probably never know for sure, although from the human point of view the possible correlation of longevity to metabolic rhythms is suggestive. People with higher metabolic rates do seem to have shorter lifespans; this is one index which accounts for the differences in longevity between men and women. Men have shorter lives and higher rates of metabolism; but although subjective testimonies on this score might be easier to acquire for men than for mice, they are hard to find. Still, it is doubtful whether most men would feel that "living harder" compensates for living less long.
In addition to the daily cycles, some species are adapted to annual or even longer-term rhythms. Migrating birds make their treks regularly at the same time of the year; cicadas, rather amazingly, emerge from below ground to lay their eggs at either thirteen-or seventeen-year intervals, almost to the day. This suggests that, even if animals may not be aware of the future — in our sense of "awareness" — some instinct of futurity, or long-term temporality, seems to be built into many organisms. It is surely such an instinct — or mechanism of inner temporal regulation — which allows squirrels to put away food for the winter, or which drives certain fish to time their mating so that their off spring can emerge in the most favourable seasonal conditions.
Does that mean that some animals, in some sense, "know" about the future — and what sort of "knowing" would this be? The question of animal perception of time, as of animal experience altogether, remains a philosophical conundrum of the same order as that posed by the philosopher Thomas Nagel in his famous essay, "What Is It Like to Be a Bat?" What is certain is that each species has its specific time-patterns, or its temporal nature, which remains, within certain parameters, quite fixed, and which changes only through the extremely slow processes of evolution. Each animal is, in a sense, adapted not only to its own environment but, so to speak, to itself. Why and how that comes about seems to be, so far, less clear. One might cite Antony, in Antony and Cleopatra, as he tries to answer the question about what kind of thing is the crocodile: "It is shaped, sir, like itself," Antony answers, "and it is as broad as it has breadth. It is just so high as it is, and moves with its organs. It lives by that which nourisheth it, and the elements once out of it, it transmigrates." And, Antony might have added, it progresses through its days and nights very much at its own pace.
* * *
Can the same be said of humans? Are our temporal parameters also biologically calibrated? Do we, like Antony's crocodile, have a nature which is right and proper to us? Certainly, like other living organisms, we have a set of temporal principles built into our very genes and cells. Like other animals, we tick on biological clocks and, as in other species, these work on the principle of oscillation and are adjusted to the diurnal cycle. On the most basic level, time comes into existence from within our bodies, and we experience its tempos physiologically: through the rhythms of our heartbeat, or the alternations of appetite and satiation, or the pace at which we walk.
But the question of temporal nature is, of course, much more complicated for humans than for other animals — for humankind, uniquely, is the species which is not only susceptible to evolutionary or environmental change but which causes change, intentionally as well as accidentally. Throughout our history we have manipulated all aspects of our environment and, to some extent, our own selves — and temporality has been no exception. The human lifespan has consistently increased since Homo sapiens was first spotted on the horizon. At various times and places people have worked seasonally or all year round, have spent most of their time in energetic activity or not doing anything much. Unlike migrating birds, we can follow our caprice and take off for parts unknown at any season. Mechanical transport speeds up the pace of our passage through time; meditation slows it down.
Still, are there limits to our biological flexibility? And what happens when we try to step outside them? That question is today being more dramatically tested, and contested, than ever before, and in some areas it still awaits complete answers. However, there are certain things we do know. We know, for example, that if our heartbeat speeds up or slows down beyond a certain point, we get heart attacks or die. We know that humans cannot run much faster than the four-minute mile. Seventeen seconds have been shaved off the record since that first sub-four-minute run by Roger Bannister in 1954, but unless we inject superdrugs or hyper-charged microchips into our bodies — unless, in other words, we become bionic, rather than human as we understand that term — a two-minute mile is highly unlikely.
We also know that humans need sleep. Sleep is a complex and seemingly highly flexible temporal behaviour. In earlier times, people adjusted their sleep to sunset and sunrise; they went to bed shortly after sunset, and slept longer hours in the winter than in summer. In medieval European villages, peasants often got up in the middle of the night and engaged in various activities before going back to (the usually crowded) bed. The optimal amount of sleep varies from person to person, and metabolic temperaments are divided between early-birds and night-owls. And yet, as studies of the sleep state and its disorders proliferate, it is increasingly clear that each person needs his or her metabolically conditioned quota of it in order to function at optimum capacity, or even to function at all.
On one level, sleep is the organism's way of conserving energy and refuelling its supplies. All mammals need intervals of sleep, and in all of them, sleep patterns are regulated by the same circadian rhythms and homeostatic mechanisms which affect every aspect of our physiology. That is, the drive for sleep increases with the length of time that an individual has been awake — and vice versa.
But sleep involves an alteration not only in metabolism but in the state of consciousness — although what exactly that is, or what it is for, remains to some extent a puzzle. Sleep is hardly the same as unconsciousness. Things happen while we sleep, some of them of considerable importance. There has been speculation that one crucial purpose of sleep states is to enable the brain to store new information into long-term memory or, to put it technically, to transfer data from the motor cortex to the temporal lobe. This is accomplished through a recently discovered phenomenon called "sleep spindles" — one- or two-second bursts of brain waves that intensify and subside at strong frequencies. These episodes of sudden activity occur during so-called REM (rapid eye movement) sleep, when we are most likely to dream. It is during REM sleep that the brain replenishes certain chemicals, known as neurotransmitters, which establish the connective neural networks essential for such crucial mental and physical functions as remembering, learning, problem solving and performance. And it is during REM sleep, and the bursts of sleep spindles, that new data we have taken in during the day is laid down more firmly in the neural structures of the brain, and thus transformed into knowledge which becomes more permanently a part of us.
Excerpted from Time by Eva Hoffman. Copyright © 2009 Eva Hoffman. Excerpted by permission of Picador.
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