The Seven Mysteries of Life

by Guy Murchie

  Beyond this multitemperature scheme there are the many ways and degrees of shifting the whole body into a lowered metabolism rate known as hibernation, which has been perfected by woodchucks, chipmunks and several other northern animals, and is known to take place to a slight degree even in the case of humans, such as Laplanders, Eskimos and Australian aborigines. It works because chilling is a general anesthetic that slows down all metabolic functions, reducing the body's need for food, water and oxygen to the point where it can sleep securely on its own fat until spring, breathing scarcely once a minute the while. Tests have shown too that a mammal's sight and hearing cease to function about when his temperature gets down to 94°F. or his pulse to 40 a minute. His breathing becomes undetectable around 8o°F., his heart stops by 50°F., and oxygen is hardly needed in any form below 39°F.

  THE ELEMENTS OF LIFE

  Now, having said something about the limitations imposed on animals by such factors as gravitation, altitude, temperature and humidity, we come to the question of chemistry - of the actual elements of Earth and the universe. Elements, after all, are what matters in matter, which is life's substance. And although we will later see strong evidence that material substance is a mere aspect of life, right now we may consider living bodies as material things.

  About three fifths of all the hundred known elements of the universe have been found in the cells of living things. However, this does not mean that they are all "elements of life" or essential to life. The most significant and vital element in life on Earth may be said to be oxygen. Although oxygen atoms constitute only 1/18 of 1 percent of the atoms in the known universe, they include more than one out of every four atoms in the human body, one of three in the oceans and almost one of two (47 percent) in the solid crust of our planet with all its rocks, soil, forests, animals and cities. Hydrogen is closely associated with oxygen, especially in water (H2O), and these two elements account for about eight ninths of the body, which may be two-thirds water. Carbon is likewise a prime element of life, composing about 10 percent of atoms in animals and man and a much higher percentage in vegetables, even though it is less than one fifth of 1 percent of Earth. After these in abundance for life come nitrogen 3%, calcium 2%, phosphorus 1%, sulfur .25%, potassium .2%, sodium .15%, chlorine .15%, magnesium .05%... But few of these elemental proportions of life correspond closely to those in the planet as a whole (even less so in the universe), for carbon is only the eleventh most abundant element on the earth's surface and even hydrogen forms less than a quarter of one percent of solid Earth, while silicon and aluminum (important bulk elements in rocks and soil) comprise 28% and 8% respectively of the terrestrial surface, yet are scarcely detectable at all in living tissues, though many creatures use silicon in feathers, shells, horns or in the skeletons of coral, sponges, radiolarians, etc. So it seems that life is quite selective as to the ingredients it chooses from those present on the planet. And it is in keeping with this principle that certain elements which life uses only in microscopic amounts are absolutely essential to it notwithstanding. For tests have conclusively proven that, unless animals and plants find and ingest these particular "trace elements," they must soon sicken and die. These vital traces, interestingly enough, include such metals as iron, copper, zinc, chromium and manganese, without at least a little of which neither animals nor plants can live - four atoms of iron being required, for instance, in every molecule. of hemoglobin, which is the red in blood; copper and zinc in enzymes connected with breathing; etc. And they include cobalt, fluorine, selenium, molybdenum and iodine, all vital to animals.

  A good example of a trace element that loudly signals its own absence is iodine, because a dearth of iodine in food and water brings out goiter in human beings. Only one atom of iodine in ten million in the bloodstream, however, is enough to prevent this swollen thyroid disorder by bolstering the metabolism-regulating hormone thyroxine with this vital element, which forms 65 percent of the thyroxine molecule. In evidence, just recall how easily the widespread adoption of iodized table salt has overcome the goiter problem in iodine-deficient areas such as certain inland parts of central Europe or mountains in the northwestern United States.

  And the story is similar with iron, copper and other elements, which are like microscopic keys linking the minerals of Earth to its creatures. A single ounce of cobalt, for example, which provides the central atom of each vitamin B12 molecule, will sustain 800 sheep a whole year - but without it they quickly become anemic and start dying off. And sometimes trace elements have complex interrelationships, as exemplified by Australian sheep that get copper poisoning in pastures rich in copper but poor in molybdenum or inorganic sulfate - their deadly ailment being relieved only by feeding them a minimal trace of molybdenum together with sulfate, a combination that in some not-yet-clearly-understood way always manages to counteract the excess of copper.

  Trace elements, like all other material substances and no doubt many immaterial ones, thus can become poisons when taken in large enough quantities. The purest water will kill you also - and not necessarily by drowning - if you take enough of it. And strong acids and alkalis of course have a violent corrosive effect, killing cells by the billions and often destroying a large animal by hemorrhage, shock or disintegration of some vital organ. But weaker poisons may be equally, if more subtly lethal by merely nudging the sensitive acid-alkaline balance of the body beyond the tolerance limit of vital chemical reactions. Or, more subtly still, by barely interrupting some intricate chemical reaction upon which metabolism (therefore ultimately life) depends. Yet, despite the delicacy of organic chemical balance, a number of creatures have managed to evolve an amazing tolerance for particular poisons - among these the venomous animals and their parasites, or specialized ones like the brine fly who lives in the vats of saltworks, an oil-loving cousin who makes his home in petroleum pools, or the amazing drugstore beetle who can live for generations inside a bottle of belladonna, ergot, squill or any of a hundred other dangerous drugs. But of course even these animals must feel constrained and limited by their own exceptional, if not easily understood, adaptations.

  LIGHT

  And if the chemistry of the earth, along with its gravity, temperature and humidity, can thus so severely discipline its life, one cannot afford to overlook the intangible but vital factor of light, the absence of which (as we have already noticed) makes it virtually impossible for any plants to grow in the black depths of the sea, and in somewhat different ways has a comparably profound effect in the black underground caverns of the land. In mentioning caverns, of course I am not thinking of the open areas near cave entrances inhabited by bears or mountain lions or men. Nor of the twilight zones farther in, where bats and owls roost and sometimes phoebes, jackdaws or hummingbirds, alongside of cave rats and all sorts of crawling things and a marginal vegetation of pale ferns, moss, mushrooms, lichen and algae. What I have in mind rather are the deep recesses of so-called absolute darkness, thousands of feet beyond the dimmest noticeable light. The only bird that penetrates this far is the fabulous guacharo or oilbird of Venezuela, which, in spite of its four-foot wingspread, has been known to congregate in raucous flocks exceeding 5000 in a single great cave, each bird navigating by its echo-location acoustic system similar to the sonar of bats (page 206), flying out into the open sky every evening at the gentle invitation of the gloaming, driven back to the cave each dawn by the gathering glare of day. Among those other creatures that do not emerge at all from the inner blackness even at night, there is little need for eyes and, as a consequence, any vision their ancestors bequeathed them seems to have devolved toward blindness. Indeed, as in the deep sea, the only call for sight in the innermost caves would seem to come from the occasional evolvement of luminescence, such as that of an exotic maggot of New Zealand which spins silken pendulums with beadlike globules of sticky mucus that glow blue-green in the darkness of certain grottoes and help lure and catch moths and other flitting insects that retain some vestige of vision. Among most of the mollu
sks, snails, slugs, crayfish, bugs and amphibians of such ink-black realms, palps are expectably much more developed than eyes, while hairs are used less for insulation than for feeling out one's prey or enemies. And there are innumerable special and looping food chains, such as those of insects that eat molds that grow on bat guano produced by bats that eat insects that eat molds.

  While a few animals seem able thus to persist in pitch darkness for long periods, life in general on Earth both needs and appreciates the light. All the terrestrial food chains, for example, are firmly based on photosynthesis, and even the most addicted cave dwellers who "never" emerge must derive their ultimate nourishment from plants or seeds that originated in the light before they were washed or wafted or elsehow carried to the inner dark. And one should never forget that the influence of light is just as important at sea as upon land, since about three quarters of all the photosynthesis taking place on Earth occurs in the oceans. In fact, just as rabbits and deer graze on mountain meadows, in turn becoming meals for the prowling flesh eaters, so does all sea life pyramid upon the tiny one-celled algal "grasses," which are munched by plankton smaller than a pinhead, which are eaten by slightly larger fish, which later are devoured by still larger finned creatures, and so on up the scale of sizes in a seemingly ruthless but almost automatic winnowing process of eat and be eaten. And both these complicated food chains, on land and sea, are founded on the energy of sunshine that sparks the inexorable regimen of photosynthesis - something still quite mysterious yet so profound and important that you can be sure we will be looking at it with a much closer eye before we get through the next chapter.

  Right now we only need to notice light's direct and extraordinary power to control almost every creature alive: through seasonal changes in the lengths of days, through rhythmic dawns and dusks, even through the reflected glow of the moon. How do birds know when to fly south in the fall? Or in what direction to head? Obviously whatever guides them can be no casual half-hearted influence when we consider the numerous authenticated reports of birds that have overcome their powerful parental instincts and actually abandoned their late unfledged broods to starvation rather than deny the irresistible call of the southland. And there is no doubt left that the shortening days and declining angle of sunlight are what mainly triggers this seasonal migration. Indeed a ponderable helping of recent research has established the reality of a surprisingly precise animal awareness of light, amounting to a celestial navigation sense, not only among bees and birds but extending to fish, reptiles, mollusks, worms and microorganisms. And this discipline of light, which includes starlight, moonlight, lightning, man-made illumination, animal luminescence and other forms, is already accepted as a key factor in the regulation of life in general - which naturally includes vegetable life - and most of the major rhythms of the body and its behavior are directly or indirectly geared to light. Not only are the sleeping and feeding habits of nearly all animals and man attuned to the 24-hour daylight-darkness cycle, but so are the entire life spans of some insects (mayflies for example), and innumerable lesser events from the diurnal color changes in fiddler crabs to the pulse rates of wombats and the metabolism of the twite and the smew...

  I am told that snowshoe rabbits, for example, when blindfolded for an hour each autumn day, turn white earlier in the season than do unblindfolded rabbits, because visually shortened days act as potent "light signals" to forewarn their enzymes and prepare their fur for the coming of winter. Isn't it for the same basic reason that blind adolescent girls have their first menstruation later than girls who can see? And what about the crows who, after being illumined by artificial daylight before dawn on winter mornings, ripen their reproductive organs earlier and migrate sooner than their unenlightened brethren still roosting in the dark?

  These are the merest hints at the influence of light upon life and its countless rhythms cadenced so inexorably to the motions of the celestial spheres. For, like gravity and temperature, light is as abstract as it is pervasive, and there is no known end to the constituents in its dominion. Nor are there definable limits to many of the other forces that shape life and its functions in the known worlds. So we must try to content ourselves as best we may with this sketchy overture to an immense subject, because, in a book like this that deals with all life, one must conserve and budget one's pages if one is to have room to investigate and write about life's numerous other and less-known aspects.

  I therefore wrap up our space age bestiary of God's creatures without having yet discovered much more about the life of our sample planet than the scrimpy evidence already presented that animals are formed and limited in many unobvious ways by the Earth they are made of - an Earth indeed that seems to involve so much more than any man can hope to dream of that its total meaning is, for all I can tell, about as unfathomable as the Milky Way.

  Yet, one wonders: is life also essentially good? Is planetary existence in any sense founded on wisdom, or love? Or are we rather drifting before the aimless winds of chance? If life turns out to be not wholly random, does that in itself imply a purpose to it, a design or possibly a spunk of something divine?

  We have still to come to grips with these larger questions and, until we do, we cannot be fully aware of this node of flesh nor possibly realize what whole it is part of. Nor can we even learn whether a virus may potentially see the stars - nor in what billennium a coral polyp may at last discover the continent it created.

  So let us listen to the quiet texture of the sphere. Let us sip our wine on the vine and whisper freshly with gentle grasses. Let us twine our toes into roots, surge with the sap and hearken to great trees. For theirs is a life that is older than animalness, deeper than thought, and that may well penetrate the primordial genesis of us all.

  Chapter 2

  Realm of the Vegetable

  * * *

  AS I LOOK DOWN almost casually upon the dark blue and cloudflecked expanse of forest in northern South America, then upon the even darker jungles of central Africa, a curious nostalgia begins to pervade me. It derives from a sensation as strangely comforting and inexorable as the turning of the earth, which I can read like a clock from here, an instinctive realization that my flesh and bones are somehow parcel of that bulging mantle of vegetation that girdles the middle latitudes.

  I wonder at the meaning of it - at the profundity of the relationship - as I recall, not without conscience, my most intimate arboreal affinities in two thirds of a century. During that time I have not only climbed many a tree but have consumed them in stoves and fireplaces in untold numbers. Though most often heedless, I've also been an admirer of trees and occasionally their midwife, nurse, godfather, pupil, trainer, experimenter, surgeon, conductor, executioner and undertaker. I wonder how much awareness in return any tree has had of being my staircase, watchtower, lumber, fuel, plaything, nursling, teacher, pupil, subject, patient, passenger, victim or corpse. However slight, I feel there has always been some degree of withy cognizance, which, in mathematical terms, must have had a value greater than zero. Or, if I may express it more humanly, is it not appropriate that I, a representative of mankind, should pause now and then in a forest to shake hands with a sociable bough? Or metaphorically to thrust my feet into roots until, wringing my empathy to its utmost, I imagine I can begin to sense just the tiniest inkling of the feeling of being a tree? Even guess that the tree may sense me?

  I feel sure the venerable peasants of the Austrian Alps and other old-time woodsmen all over the world are not being unreasonably superstitious when they beg a tree's pardon before pruning it or chopping it down. Nor need any of us scoff at the beautiful symbolism, which is said to have originally inspired this tradition in the almost universal recognition of tree spirits, in concepts like the Persian Tree of Immortality, the bo tree under which Buddha received his enlightenment, the Hebrew Tree of Knowledge which opened the eyes of Adam and Eve, and in such powerful myths as the Scandinavian legend of the world tree of Yggdrasil, Odin's sacred ash of celestial dimensions, w
hose monstrous roots penetrated the subterranean kingdom of death, where the wily serpent Nidhogg gnawed at them ceaselessly and whose prodigious upper branches tossed among the stars of life (still commemorated in Christmas tree decorations) where four stags browsed daily upon their tender buds. The bards have it that, despite these dual consuming influences of death and life, the Yggdrasil tree's supernatural growth kept it constantly green, ever new, so that its heroic trunk bound Heaven to Earth and formed the imperishable structure of creation.

  The appropriateness of such an archetype for our planet is striking, for vegetation in quite a real sense does bind the sky to the Earth. Not only is vegetation the land's chief organ for absorbing rain that falls from the clouds and (after using it briefly) evaporating the same rain from its leaves back into the sky to maintain the terrestrial circulation, but vegetation quickens and conserves the entire atmosphere by inhaling excess carbon dioxide and exhaling vital oxygen, the while holding up mountain ranges, stemming erosion with sterns, rooting soil with roots, directing the courses of brooks and rivers and literally leashing stationary clouds to wooded slopes with invisible thongs of humid wind.