The Seven Mysteries of Life

by Guy Murchie

  PARASITISM

  This sort of drastic interdependence of microbes evidently achieves its ultimate complexity in parasitism, which, as I mentioned in Chapter I, has evolved natural chains or hierarchies, such as viruses that are parasites of bacteria that are parasites of certain very small mites that are parasites of lice that are parasites of egrets that are parasites of cattle that are -parasites of man who is a parasite of Earth which is a parasite of the sun which is a parasite of the Milky Way which is a parasite of the Virgo Supergalaxy ... with each host bigger than its parasite like a nest of Chinese boxes all the way (if enough were known) from the heart of the atom to the horizon of the universe. The numbers involved are staggering. When you allow for the vast multitudes in the microworld, at least half of all creatures are parasites in some way dependent on the other half, many of them host and parasite at the same time - with the evolving food chains or predation pyramids often dependent in the reverse direction. Great sharks, for instance, eat large fish who have fed on smaller and smaller ones all the way down to invisible plankton. Yet other creatures cut short or change the chains like certain whales who once grazed directly on plankton, then learned to feed on krill (who eat plankton), in effect turning the krill into spoons for easier plankton consumption.

  Birds at first glance seem such carefree spirits you wouldn't suspect they are also zooming zoos of parasitism that include millions of passengers from fleas, leeches, beetles, flies, mites, ticks and feather lice to much larger numbers of microbes ranging from specialized flukes and worms to bacteria and viruses. Did you realize, for instance, that the eight thousand known species of birds are inhabited by twenty-four thousand less known species of feather-eating lice plus fifty-odd thousand species of other parasites, mostly beetles and mites? To the louse inside a quill, of course, the bird and its outer life of flight and song are completely unknown, as are your life and thoughts to your bacteria and viruses and the myriad other unseen passengers that inhabit your body, roaming the deserts of your wrists and arms, swimming your lymph, slithering through your intestines, exploring the cool woods of your scalp, wallowing in the tropical jungle of your groin. You may be surprised to know, for one example, that a weird eight-legged miniature "alligator" with long tail proliferates unseen (but not quite invisible) among the eyelashes of most people, particularly elderly females who prefer "cleansing" cream to soap. It is a nocturnal mite known to science since 1841 as Demodex folliculorum and it breeds shyly in the dark pores of the human face where it lives out its two-week life span, browsing nightly on the oily sebum of hair follicles, one of many uninvited but relatively harmless passengers scuttling about your person, some in your blood or your muscles but in this case usually just under the scaly squames of your skin.

  Some parasitic flies actually live inside the stomachs of horses, zebras and elephants. Some dwell in the eyes and nostrils of frogs. Some hijack blood from mosquitoes that are already gorged. Some live on such dainty morsels as the brains of ants, the tears of hummingbirds, or the antennas of butterflies. There are moths that live in the eye creases of cattle. There are more than 100,000 species of parasitic wasps, many of which live on other parasitic wasps.

  In the sea large fish commonly get their teeth cleaned by small "cleaner" fish who specialize in this type of dentistry so they can feed on the crustaceans, fungi, lice, bacteria and other tiny organisms that inhabit or infect their big cousins. At least 28 fish species are already known to have taken up this and the related grooming profession, plus six species of cleaning shrimp, a crab, a worm, and a bird or two. And they are all in such demand that their big and itching clients usually have to wait in line, which, in the busy season, may mean all day.

  Not a few parasites eventually contrive to outgrow their parasitism, as, for example, the gall insect that has the gall to ask the tree's help and gets it by laying its eggs (which imitate seeds) in certain tree tissues, causing a protuberance or gall that nourishes the larvae and often lives longer than the branch it is on - then, having fallen to the ground, puts out its own roots as if it were an independent, interkingdom organism.

  The eating of one species by another is also of course a widespread interrelation which, on the mammal level, seems nightmarish to a human. Yet, on lower levels, such as those of reptiles and amphibians, the animal being eaten seems hardly to care whether he is eaten or not. And there are still lower levels where the prey not only doesn't mind being, but actually yearns to be, eaten - cases that cease to be inexplicable as soon as you delve into the microworld of certain kinds of flukes and parasitic worms who swim up the blades of dew-laden grass and whose very survival depends so utterly on their being swallowed that they will die (without having reproduced) unless some animal of the right species soon picks them up in its mouth and "digests" them back into their natural intestinal habitat.

  There is no end to interrelations anywhere. The polyphemus moth cannot mate until it receives a chemical sex attractant (called trans-2-hexinel) from red oak leaves. A mosquito messenger is known to carry eggs for a fly. There are "annual" fish who swim in deserts in the temporary pools created by the brief seasonal downpours and whose eggs will not hatch until they have been shriveled by a long drought before submersion in water. An oblong tomato has been designed and bred to fit a tomato-picking machine, which, in turn, enables it to survive and evolve. Similarly both vegetables and animals are turned into geological forces by such action as jungles that stem erosion and build soil, polyps that raise coral islands, beavers that change the shapes of rivers. Even this book, written by an American, is made of paper invented by Chinese and printed with ink evolved out of India and from type developed largely by Germans using Roman symbols modified from Greeks who got their letter concepts from Phoenicians who had adapted them partly from Egyptian hieroglyphs.

  Thus do abstract threads weave the living tapestry of Earth, our familiar world in which lupines love volcanoes, where a rock may give a brook its song, a world where surgeons have recently learned to transplant organs (containing genes) from one body to another, thus literally binding closer the brotherhood of man and, in some cases, the cousinhood of animal and man. Even when they implant artificial organs that have no genes, surgeons are reducing the disparity between man and machine, between animal and mineral, possibly even between life and nonlife, a subject we will explore in depth next chapter.

  Which is as it should be upon this itching node where vegetables and animals and stones confer and beckon to one another, even warn each other, implore, love, admonish, kill ... How better could sweet basil express his disgust with bitter rue? How more eloquently might shy rose offer a bee her nectar? Or, with her thorns, deny the plucking hand?

  Chapter 14

  Third Mystery: The Omnipresence of Life

  * * *

  IMAGINE AN EYE looking through a system of lenses upon a crystal growth spreading out in irregular cubic patterns. Slowly the crystal grows, like a snowflake extending and branching its arms and fingers into more and more complex shapes, all of them unique. Then suddenly there is a flash and most of the crystal disappears - yet it soon begins to grow again, faster and more luxuriantly than before.

  What is this crystal? Is it frost on a windowpane or a culture of viruses? Is it alive?

  Actually it is a city on Earth as seen through a powerful telescope stationed in space. It comes to the eye as from a series of pictures taken one per month over several centuries, then projected on a screen condensed into a time-lapse movie lasting a couple of minutes. It is Hiroshima, which was vaporized in 1945 but is now reborn and crystallizing faster than ever, a tiny sample of life as seen from outside - from out here between the worlds - and, incidentally, by making use of a technology that is well within the present capability of Earth.

  I have set myself the task of defining life in the broadest possible perspective, you see - something I don't expect will be easy. Let us take a city, any city. Considering it as a whole, is it a living organism? Engineers have estima
ted that American cities are now rebuilding themselves on a 35-year cycle, European ones a 50-year cycle, oriental ones perhaps a 75-year, these being city metabolism rates that have speeded up as the cities matured and which suggest basic attributes of life along with such urban physiology as water and sewage systems, arteries, tubes, power lines, communication nets and other parts to be expected of large viable organisms.

  A meteor blazes across the black, starry sky. Can we regard it in some sense as alive? A trickle of water meanders like a snake down a dirt path, sensitively searching for the lowest ground. Is it alive? Microscopic grains of dust swim jerkily in water in the phenomenon known as Brownian movement. Are they alive? Are stars alive? Are atoms and electrons alive? Is the ocean alive? What about the winds and the clouds?

  Pygmies in the Congo say the forest itself is a being, for they can hear its treetops and its streams murmuring assurance to its human and animal children. There is scientific justification for this intuition too in the known facts of vegetable respiration and interrelated motion, the hormonal interdependence of branches, the groping of roots, and especially in the collective migrations of vast populations of trees and their inhabitants. Biologists also speak of pheromones circulating in the sea as the social hormones of that finite but endless organism. A thunderstorm, composed mainly of volatile gases, behaves something like a primitive animal - in growth, in circulation of wind and rain, in nerve response of lightning, even in reproduction which, as with the ameba, is simply the splitting off of new cells from the old.

  Does the tree, I wonder, seem alive to the termites who burrow in it? Or the turtle's shell to the turtle - the turtle to the shell?

  Greek philosophers of the sixth century B.C., who seem to have thought as deeply and with as little prejudice as any philosophers in history, taught that life is a natural property of matter, an inevitable manifestation of the truth that the world has always been alive. Thales led the way by declaring that all matter including minerals, gases and stars is alive. Then Anaxagoras propounded his panspermic theory that invisible "ethereal germs" are dispersed everywhere in the world, giving rise to all its creatures including man.

  Two centuries later Aristotle went along with the panspermists to the extent of saying "Nature makes so gradual a transition from the inanimate to the animate that the boundary between these kingdoms is indistinct and doubtful." To this Saint Augustine long afterward added a mystic factor with his concept that the world is full of "hidden germs (occulta gemina)" of an unfathomable spiritual potency that somehow spawn living creatures out of earth, air and water. Still later Descartes, after describing man's body as a kind of "machine made of earth," conceded to his critics that there must be a "ghost within the machine" presumably connected to it by the pineal gland.

  Thus the consensus of philosophical opinion developed, continuing in this day, and it still largely accepts the universality of life, acknowledging that all creatures, including man, are made of the same materials as the world - while there also must be something nonmaterial in man, some ingredient that cannot be hit with a stick or despatched by a bullet. And, on the superorganic level of cities, the spreading conglomerates of brick and mortar are just as surely analogous of vegetables and animals with their stem arteries conveying nutriment and their developing "blossoms" that metabolize continuously while bustling barges hover about their docks like pollinating bees.

  THE SECRET LIFE OF ROCKS

  When it comes to rocks, understandably they are not considered alive by most people. But, as Omnipresence is the Third Mystery of this book, we are clearly called upon to search for life everywhere, including where it is least expected. And where would one expect life less than in a stone, which lies still on the ground as if dead without showing any of the signs commonly associated with life?

  But let us not be hasty for, although stones seem inert, perhaps it is only because their life is geared to a tempo far slower than that of most vegetables, which in turn, as we noted on page 371, move about 40,000 times slower than comparable animals. Indeed I reckon a timelapse movie of rocks in the large would have to speed up the passage of years and millenniums by at least another factor of 40,000 before one would likely notice much change or other signs of mobile life.

  Yet rocks do experience a kind of life, even a metabolism of sorts (which we shall return to) - and I am not referring to anything like "flowering stones," the pebble-imitating plants that have evolved into hundreds of species in South Africa. If you have ever personally met a volcano or felt an earthquake, you must agree that rocks are not always passive. And what is the moon but a huge stone weighing 81 quintillion tons moving daily over our heads at better than a thousand miles an hour? Come to think of it, the biggest and fastest moving things we know of anywhere are neither animal nor vegetable but primarily of the mineral (or plasma) kingdom: a hurricane, a forest fire, an H-bomb explosion, a river in flood, the raging sea, the earth, the sun, the stars ...

  But mobility is characteristic also of cool, quiet rocks, which, in their own way, manage to get around. If they happen to live near active animal or human life, they may be pushed, plowed or kicked about, or even thrown. Growing trees may heave them aside, young mountains lift them or weather erode them. Some rocks (pumice for example) are so light they float on water and thus drift about the seven seas. Any rock as small as a pebble is likely to begin to travel, particularly if it is on a hillside or in a river or is picked up by a glacier that will break into icebergs. And pieces as small as sand can easily take to the air, as in a sandstorm, and migrate swift as the wind to virtually anywhere on Earth. In fact it hardly stretches reality at all, in a very broad sense, for us to start thinking of rocks as growing, basking, shivering beings with a limited but very real life of their own.

  The authorities on this subject of course are mineralogists, who, with the aid of their modern arsenal of instruments, have accumulated conclusive proof that some rocks literally do grow, that some ungrow, some glow, some radiate, some disintegrate, some (like asbestos) are hairy, some (like oil shale) are insolubly organic and some ever get ill (perhaps from poison) and later return to good health. You probably have seen sick stones yourself in the form of calcareous carvings on old city buildings, which are commonly crusted with sulfurous dust from smoke and exhaust fumes, which eventually thicken into blisters or cankers exuding sulfuric acid that eats inward until rain and wind erode the scabs, allowing the powdery decay underneath to ooze like a leper's sores.

  Modern stone doctors of course are learning how to cure and prevent such ailments, along with their accelerating knowledge of the mineral kingdom, which presently recognizes about 1,500 species, each with a characteristic form that is the outside expression of a highly organized interior. The Linnaeus of the mineral kingdom was James Dwight Dana, professor of mineralogy at Yale in the nineteenth century, who classified rocks and other minerals on such a sound chemical basis that it has become the accepted standard for the world. As with animals and vegetables, several new species of minerals are discovered and approved each year but, unlike the overall increases in these other kingdoms, their net number decreases during this early period of chemical science as old mineral "species" keep having to be demoted to mere "varieties" when it is revealed that they are chemically similar to other kinds that originally seemed different.

  The changes in size, position and composition that take place in rocks are often surprising even though orderly and germane to their lives. One is apt to assume, for instance, that grains of sand come from the simple polishing away of boulders and stones into gravel and smaller pieces as they are washed down mountainsides and swept seaward in streams or beachward by the sea, but a little reflection will show that by that process it would take a shipload of rocks to make a pint of sand. What really happens, according to geologists studying erosion, is that sand is born in the "chemical and mechanical disintegration" of large masses of gneiss and granite, most of it due to weathering, freezing, glacial friction, expansion, cont
raction and the subtle gnawing of tiny mollusks in the sea plus lichen and other vegetation, most noticeably on dry land. Thus the fact that smaller and smaller grains are found as you go downstream is not because of the water's polishing action (actually negligible) but rather because the slowing current permits progressively smaller particles to settle to the bottom in accordance with the hydraulic engineer's rule of thumb that "the carrying power of a stream varies as the sixth power of its velocity."

  Thus sluggish pebbles generally appear in brook beds while light silt and clay, moving swiftly in suspension, reach estuaries and the ocean in large masses. Intermediate grains of sand may be almost anywhere between, traveling at their individual paces, bouncing along the bottom from pool to pool, resting perhaps a year in a shallow one, a century in a deeper one, a millennium in a very deep one, awaiting the scouring action of a rare flood to boost them free. A typical river may take something like a million years to work its sand a hundred miles downstream at an average rate of six inches a year or fifty feet a century.

  Although not whittled by abrasion in rivers, rough young sand grains do gradually get their corners rounded and their surfaces polished by the chemical action of water, so slowly however that, as one geologist reckoned it, a half-millimeter cube of quartz would need to be swept down a raging torrent for more than a million miles before it could possibly be smoothed into a sphere. Surprisingly, air is a lot tougher on such an object than is water and, sooner or later, air is likely to get its clutches on it, for this common size of sand produced by ice disruption is, seemingly by divine intent, just small enough to be easily whisked up by a gust of wind yet large enough to be abraded by it. Indeed when the wind whirls coarse, angular crumbs of rock against each other, they grind away hundreds of times more mass per mile than they would in a river. Round grains, however, wear less than jagged ones and small ones less than big ones while spherules of quartz only one-tenth millimeter in diameter bounce off each other like billiard balls, leaving no trace of abrasion under the closest microscopic inspection.