Do you know how old you really are?
When your age is forty your heart might be fifty, your liver thirty-five, your arteries sixty. New atom-age tests make a liar of the calendar by showing how some parts of your body wear out faster than others
N. J. BERRILL
IN SPITE of popular belief, life really doesn’t begin at forty. It begins the day you are conceived and from then on, for nine years or ninety, you grow up and you grow old. Celebrating birthdays is a pleasant convention but it doesn’t tell much about your real age. When there are twenty-six candles on the cake, your heart could be thirty-two, your arteries pushing forty, your muscles a flexible twenty-two and your brain nineteen.
The process of growing old is different for different parts of the body, and faster in some persons than others, yet for everyone it’s irreversible. You can’t hope to recapture that first fine careless rapture of seventeen though you may indulge in wise and witty speculat ion on its meaning at eighty. As Shakespeare put it: “From hour to hour we ripe and ripe, and then from hour to hour we rot and rot, and thereby hangs a tale.”
The tale is you and me. We grow old. The important question is: how soon? Most of us count off the years with a calendar and time with a clock. Calendar and clock are fine for sowing spring gardens and catching trains but they tell us little about our actual age. The time we live is measured by a beating heart rather than a ticking clock. And by this, the really essential yardstick, most of us never know how old we really are.
The heart beats according to its own measure, with a rest after every beat, for as long as we live. When it stops, we stop. With each beat we grow a little bit older, and according to this reckoning we paradoxically grow older faster the younger we are. At birth the heart beats one hundred and thirty to one hundred and forty times a minute and is already slowing down. At twenty-five it levels off at about seventy per minute. This pace is then kept throughout most of adult life, although it will rise again at the age of ninety-five to about eighty per minute.
Does the heart beat a certain number of times and then stop from sheer exhaustion? If so, we would have a fair index of age: you would be middle-aged in the true biological sense of time when the heart had beat half of the total number of times it was destined to beat, as it does in certain lower animals. Yet if we apply the principle to humans it places middle age closer to thirty than to forty. In fact, if we look for the peak of performance of the heart and circulatory system from the point of view of adaptability and capacity for effort we find it at about fourteen or fifteen years of age.
As you grow older the heart sends forth less blood with each beat and becomes progressively less efficient as a pump. Accordingly, for a certain degree of exertion, the older heart has to beat faster than the younger one just to keep up the same flow of blood. There is another limitation. As the heart grows older the ceiling for the pulse rate becomes lower. Under conditions of stress the older heart cannot beat either fast enough or powerfully enough to allow the body to do what it may have done some years before without discomfort.
The heart is only part of the picture of ageing. The arteries are just as important, for arterial elasticity or the lack of it can help or hinder the flow of blood upon its way. “A man is as old as his arteries” is an old saying but it is only since the atom bomb exploded that we have had any accurate way of telling how old the arteries are. Now it is possible to inject a radioactive tracer into the bloodstream and in thirty-five minutes get a number that is an accurate indication of artery age. A small amount of radioactive sodium salt is injected into a vein in the arm and a Geiger counter is put over the chest to check on radioactivity as the substance flows through that region. This shows the rate at which blood flows through the great strategic vessels— twenty seconds in a healthy and normal man of twenty. In males of forty the time is doubled, and tripled for those of sixty. After twenty the time increases a second for every year.
According to tests made with some three hundred persons, the artery age of women is about five years lower than that of men of the same calendar age, which may well account for the fact that women on the average live a few years longer than men.
Yet more important is the way in which the test can be used to warn patients of possible hardening of the arteries, heart attacks and apoplectic strokes. It shows that people suffering from premature artery hardening may have an artery age of fifty or sixty though their chronological age be only forty.
Artery condition is important but is no more than the measure of a weak link and does not in itself indicate fitness or lack of fitness. According to John H. Lawrence, of the University of California, a man is as old as his ability to expel nitrogen from the blood. Like the artery age indicator this fact was discovered by means of radioactive tracers.
About a liter of gaseous nitrogen is dissolved in the body fluids of the average adult living at sea level. Gaseous nitrogen is inert, but a certain amount is held in the blood in equilibrium with the nitrogen in the atmosphere. The total amount of nitrogen stays constant, but there is a steady turnover of the nitrogen molecules of the surface of the lung. The rate at which this exchange takes place is a good index of the total efficiency of the lungs and the circulatory system.
The human guinea pigs in these experimen s inhaled small amounts of radioactive nitrogen as tracer material. Lawrence determined how fast they eliminated nitrogen by collecting the exhaled gases and counting the tagged atoms with a Geiger counter. The older a person is the slower the nitrogen turnover. Youngsters of fifteen, at the cardiovascular performance peak, eliminated half the gas in only a few piinutes, while persons of sixty-five or older took as long as five hours. Obviously much more than artery age is being measured, something much closer to the total efficiency of the human machinery. Patients in poor physical condition for instance had abnormally slow turnover rates.
In the words of Oliver Wendell Holmes, the noted American jurist, “We must all be born again atom by atom from hour to hour, or perish all at once beyond repair.” It is true, and investigations at present being conducted at several Canadian universities, employing radioactive phosphorus, carbon, calcium, iodine and sulphur obtained from the atomic energy
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Do You Know How Old You Really Are?
CONTINUED FROM PAGE 13
laboratories at Chalk River, indicate that the continual replacement or turnover applies to practically the whole body. Only the deeper parts of bone crystals seem to be more or less permanent, and it is doubtful whether we can properly describe these as being alive. We are all in fact mostly a balance sheet between gain and loss, with the margin of safety getting steadily less as the years go by. For this is what ageing really amounts to; and it is not just a matter of the replacement or displacement of mineral salts. It applies to cells and tissues too.
This shows up in a most striking way in the rate at which a skin wound heals over. Here we find a dramatic contrast between biological time and calendar time. According to the late French scientific writer, Lecomte du Noüy, a skin wound about two inches in diameter heals over in twenty days at the age of ten, in thirty-one days at twenty, forty-one days at thirty, fifty-
five days at forty, seventy-five days at fifty and about one hundred days at the age of sixty. These figures show in a startling manner how the biological clock slows down relative to calendar times and suggests a possibly accurate but certainly painful and tedious way of judging one’s biological age.
As tissues age less and less water is retained by them and they become accordingly less able to dissolve other substances. In consequence pigment and fat, cholesterol (a fatty substance found in all tissues) and calcium salts accumulate wherever the metabolism of the body is weakest: in the lens and cornea of the eye, in the eardrums, and in the walls of arteries. As the teen age comes to an end fat disappears from the face and starts to descend the body slowly, like a glacier, accumulating more and more below the belt until it reaches bottom somewhere in the middle ages. Cartilage becomes degenerate and calcified: vertebral discs become thinner and smaller and tend to slip out of place. Ears and nose become stiffer, the chest more rigid, the space between the ribs gets smaller. Fibrous connective tissue partly takes the place of muscle fibres. The chicken gets tough. Old eardrums, less elastic than young ones, no longer vibrate to the shortest wave lengths, and old people fail to hear the sound of the cicada or locust though their normal range of hearing remains unimpaired.
This drying out of the tissues can be a devastating process. Yet it is inevitable and happens to every one of us.
Only the rate of dehydration varies, and this shows up perhaps most sharply in the eye. The lens, being normally clear and crystalline, contains no blood vessels and is possibly the least well nourished of all the structures in the body, particularly the central region of the lens which is the oldest and most isolated part. As it ages it loses water and accumulates insoluble cholesterol and proteins, hardens progressively and finally becomes opaque and dies in the form of cataract. Sooner or later it is likely to happen to anyone, but in the Dust Bowl area of this continent the number of persons presenting themselves for operations for cataract rises following periods of drought. Shortage of water evidently hastens the dehydration processes and might shorten life a little. By the same token a plentiful intake of water during adult life may help to keep you fresh and pink all over, with a sparkle in your eye.
On the other hand, whether you hinder nature or help her, the hardening processes go on in lens and arteries and bone. In the case of the lens the hardening begins about the time we first learn to read. A child can see clearly at a distance and yet will hold print so close to his nose that he almost has to squint. But by the time he is nine or ten the distance for comfortable reading has already increased a lot, and from then on the nearest point for clear reading becomes more distant with age. Usually between the ages of forty and fifty the shift becomes more striking and the nearest reading point reaches an uncomfortable thirteen inches. This is the so-called state of presbyopia, and at this age most of us are better off with reading glasses.
In fact, the age at which discomfort when reading first begins to bother you has been used as a basis from which to predict how long an individual may expect to live, in normal circumstances. The investigation was made in Germany in the years between the wars, at the universities of Göttingen and Leipzig. Nearly six thousand persons of the age group forty-four to fortynine were studied and of these about four thousand were kept track of until they died. Three groups were recognized: a normal class whose readingdiscomfort. distance varied only with a certain narrow range from the average, a super-normal class where the hardening of the lens was further advanced, and a sub-normal class that could read comfortably at a shorter-than-average distance and therefore had more flexible lenses.
The individuals of the normal class lived an average sixteen and a half more years, those with precociously hardened lenses little less than fourteen years, those of the sub-normal, betterreading class for another twenty-four years. Roughly speaking, if you don’t need reading glasses until fifty your chances of reaching the seventies are good; if you can do without them until you are fifty-five you may well become an octogenarian; but if you need them for the first time at forty then that annuity policy may mean more to your wife than to you.
In fact, forty is probably the critical age. Physical strength has been declining for about twenty years. Reproductive fertility, which was at a maximum between the age of twenty and thirty, is now in sharp decline, with that of women usually ending around forty-five and that of men about fiftyfive. This has led to attempts to extend fertility such as the sex gland operations of Voronoff and Steinach, and the more recent treatment with male sex hormones. The latter are too closely related chemically to certain potent cancer producing compounds to be
introduced carelessly into an ageing body, and in any case the various causes of old age breakdown, no matter how soon they begin to operate, cannot be removed by “stimulation” with hormones. It is too much like whipping an old horse.
No man or woman grows old all in one package, and a man of sixty-five may have a forty-year-old heart, fiftyyear-old kidneys and an eighty-yearold liver, particularly if he has eaten and drunk unwisely for too long. One man, in fact, who claimed to be ninety-one years old by the calendar, had a nerve-conduction time of a man of thirty, a kidney function of the average sixty-year-old, the perceptual capacity of one of eighty, and the general metabolism of the average ninety-year-old group. Obviously he was young for his years, although there was still a built-in clock that would strike the final hour, for his metabolism was burning at the normal rate.
All in all it is better to discover ways of ageing well than it is to find some way of extending the natural period of existence, although the search for the fountain of youth probably will continue for centuries to come. A recent and almost forgotten attempt was the Bogolometz serum publicized in 1946 in Russia and elsewhere as of greater significance than the atom bomb. Bogolometz noted that the life span of animals is five to six times longer than the period of maturation and reckoned on this basis that man should properly live to be from one hundred and twenty-five to one hundred and fifty years old. Having concluded that man’s life span was being cut short by the failure of the reticuloendothelial tissues (the lymph glands, the spleen) to fight off disease and infection, he devised a serum to pep up these tissues. Bogolometz never used the serum on himself and died a natural death.
Healthier in Canada
This kind of life extension is probably beyond our reach, certainly until we know much more than we do about why we live as long as we do. Actually the problem that faces us is of a very different kind. It is the need to adjust to the consequences of the fact that we not only age as individuals but are part of a rapidly ageing society.
In the days of ancient Rome the average life expectancy was twenty-two years. In India as recently as 1931 it was still no more than twenty-seven years. On this continent it was thirty in 1800, forty-six in 1900, sixty in 1930, and is now approximately sixty-eight and rising steadily, although at a progressively slower rate as the natural ceiling is approached. At the present time about 32 million persons in the United States are between forty-five and sixty-four, and about 12 millions are older than that. By 1980 the U. S. Department of Labor predicts that 43 millions will be between forty-five and sixty-four, and as many as 22 millions will be older than the generally accepted retirement age.
In Canada the outlook is even healthier for, according to United Nations statistics based on the annual death rate per thousand persons of population, we now stand third in a list of seventeen countries, while the United States stands tenth. Norway and Denmark head the list.
The trend will continue unless we give up our more-or-less effective control of disease and also cease to strive for a peaceful world. An atomic war would result in only a temporary reversal. Whether we like it or not the average age of the human population will continue to rise and we will have to
adopt the common sense solution of making the later decades of life more productive. It is not merely a matter of keeping the older people at work beyond the present period for retirement but of adjusting the kind of work to be done more and more to the capacities of the various age levels. The present tragedy is mainly that of the ever-increasing numbers of healthy men who are suddenly pensioned off with nothing to do. Boredom too often brings them to an early grave, while their wives, who adjusted sooner to growing old, continue to live on alone for years after.
This is not meant to be a gloomy picture, for it is an opportunity and a challenge. “Too old to learn” is but a half-truth and the fact is that while in various tests the learning scores of persons over sixty were much inferior to those of adolescents, they were only slightly inferior to those of the thirtyfour to fifty-nine age group; the decline in learning ability that occurs around the age of fifty-five merely brings the individual’s capacity down to about the fourteen-year-old level. What most of us face as we grow older is not a decreasing ability to learn but the fact that we have become set in our ways and do not want to learn new things. The machinery gets rusty from not being used.
While the body begins to age almost as soon as you begin to walk, mental potency rises sharply until the age of forty and continues to rise thereafter, although at a decreasing rate, until a climax is reached at sixty. Then there is a slow decline for the next twenty years, although even at eighty the mental standard is still as good as it was at thirty-five. It is a different mind from that of a thirty-five-year-old, but no less valuable. While the young mind tends to create new conceptions and ideas, the older mind, though suffering from impaired memory and decline in sensual qualities, possesses greater steadiness, thoroughness and wealth of experience.
The shift in age distribution in the population can be made the basis for a great cultural advance if increased longevity is paralleled by health and productiveness, and the untold intellectual treasure in the old is mined and developed. Yet for a long time now this has been an old man’s world, for they alone have had the self-confidence and knowledge to maintain the relentless momentum of the living culture. Unfortunately not only wisdom and generosity but also folly, cruelty, maladjustment and invalidism tend to be cumulative with the passing years. Similar youngsters develop into different oldsters exerting different influences on society, and at differing rates of change. Some men are mentally and emotionally, as well as physiologically old at forty; others are young at eighty and infinitely wiser. “The last of life, for which the first was made” is a line we used to remember, for the mind dominates in the later years and grows only upon what it has been fed from childhood onward. Chronic starvation at the mental level is as bad for the mind as lack of food is for the body, and the penalty is boredom and possibly death at a time of life that might have been its greatest glory. ★
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