Lives of a Cell Read online

  It is permissible to say this sort of thing about humans. They do resemble, in their most compulsively social behavior, ants at a distance. It is, however, quite bad form in biological circles to put it the other way round, to imply that the operation of insect societies has any relation at all to human affairs. The writers of books on insect behavior generally take pains, in their prefaces, to caution that insects are like creatures from another planet, that their behavior is absolutely foreign, totally unhuman, unearthly, almost unbiological. They are more like perfectly tooled but crazy little machines, and we violate science when we try to read human meanings in their arrangements.

  It is hard for a bystander not to do so. Ants are so much like human beings as to be an embarrassment. They farm fungi, raise aphids as livestock, launch armies into wars, use chemical sprays to alarm and confuse enemies, capture slaves. The families of weaver ants engage in child labor, holding their larvae like shuttles to spin out the thread that sews the leaves together for their fungus gardens. They exchange information ceaselessly. They do everything but watch television.

  What makes us most uncomfortable is that they, and the bees and termites and social wasps, seem to live two kinds of lives: they are individuals, going about the day’s business without much evidence of thought for tomorrow, and they are at the same time component parts, cellular elements, in the huge, writhing, ruminating organism of the Hill, the nest, the hive. It is because of this aspect, I think, that we most wish for them to be something foreign. We do not like the notion that there can be collective societies with the capacity to behave like organisms. If such things exist, they can have nothing to do with us.

  Still, there it is. A solitary ant, afield, cannot be considered to have much of anything on his mind; indeed, with only a few neurons strung together by fibers, he can’t be imagined to have a mind at all, much less a thought. He is more like a ganglion on legs. Four ants together, or ten, encircling a dead moth on a path, begin to look more like an idea. They fumble and shove, gradually moving the food toward the Hill, but as though by blind chance. It is only when you watch the dense mass of thousands of ants, crowded together around the Hill, blackening the ground, that you begin to see the whole beast, and now you observe it thinking, planning, calculating. It is an intelligence, a kind of live computer, with crawling bits for its wits.

  At a stage in the construction, twigs of a certain size are needed, and all the members forage obsessively for twigs of just this size. Later, when outer walls are to be finished, thatched, the size must change, and as though given new orders by telephone, all the workers shift the search to the new twigs. If you disturb the arrangement of a part of the Hill, hundreds of ants will set it vibrating, shifting, until it is put right again. Distant sources of food are somehow sensed, and long lines, like tentacles, reach out over the ground, up over walls, behind boulders, to fetch it in.

  Termites are even more extraordinary in the way they seem to accumulate intelligence as they gather together. Two or three termites in a chamber will begin to pick up pellets and move them from place to place, but nothing comes of it; nothing is built. As more join in, they seem to reach a critical mass, a quorum, and the thinking begins. They place pellets atop pellets, then throw up columns and beautiful, curving, symmetrical arches, and the crystalline architecture of vaulted chambers is created. It is not known how they communicate with each other, how the chains of termites building one column know when to turn toward the crew on the adjacent column, or how, when the time comes, they manage the flawless joining of the arches. The stimuli that set them off at the outset, building collectively instead of shifting things about, may be pheromones released when they reach committee size. They react as if alarmed. They become agitated, excited, and then they begin working, like artists.

  Bees live lives of organisms, tissues, cells, organelles, all at the same time. The single bee, out of the hive retrieving sugar (instructed by the dancer: “south-southeast for seven hundred meters, clover—mind you make corrections for the sundrift”), is still as much a part of the hive as if attached by a filament. Building the hive, the workers have the look of embryonic cells organizing a developing tissue; from a distance they are like the viruses inside a cell, running off row after row of symmetrical polygons as though laying down crystals. When the time for swarming comes, and the old queen prepares to leave with her part of the population, it is as though the hive were involved in mitosis. There is an agitated moving of bees back and forth, like granules in cell sap. They distribute themselves in almost precisely equal parts, half to the departing queen, half to the new one. Thus, like an egg, the great, hairy, black and golden creature splits in two, each with an equal share of the family genome.

  The phenomenon of separate animals joining up to form an organism is not unique in insects. Slime-mold cells do it all the time, of course, in each life cycle. At first they are single amebocytes swimming around, eating bacteria, aloof from each other, untouching, voting straight Republican. Then, a bell sounds, and acrasin is released by special cells toward which the others converge in stellate ranks, touch, fuse together, and construct the slug, solid as a trout. A splendid stalk is raised, with a fruiting body on top, and out of this comes the next generation of amebocytes, ready to swim across the same moist ground, solitary and ambitious.

  Herring and other fish in schools are at times so closely integrated, their actions so coordinated, that they seem to be functionally a great multi-fish organism. Flocking birds, especially the seabirds nesting on the slopes of offshore islands in Newfoundland, are similarly attached, connected, synchronized.

  Although we are by all odds the most social of all social animals—more interdependent, more attached to each other, more inseparable in our behavior than bees—we do not often feel our conjoined intelligence. Perhaps, however, we are linked in circuits for the storage, processing, and retrieval of information, since this appears to be the most basic and universal of all human enterprises. It may be our biological function to build a certain kind of Hill. We have access to all the information of the biosphere, arriving as elementary units in the stream of solar photons. When we have learned how these are rearranged against randomness, to make, say, springtails, quantum mechanics, and the late quartets, we may have a clearer notion how to proceed. The circuitry seems to be there, even if the current is not always on.

  The system of communications used in science should provide a neat, workable model for studying mechanisms of information-building in human society. Ziman, in a recent Nature essay, points out, “the invention of a mechanism for the systematic publication of fragments of scientific work may well have been the key event in the history of modern science.” He continues:

  A regular journal carries from one research worker to another the various . . . observations which are of common interest. . . . A typical scientific paper has never pretended to be more than another little piece in a larger jigsaw—not significant in itself but as an element in a grander scheme. This technique, of soliciting many modest contributions to the store of human knowledge, has been the secret of Western science since the seventeenth century, for it achieves a corporate, collective power that is far greater than any one individual can exert [italics mine].

  With some alternation of terms, some toning down, the passage could describe the building of a termite nest.

  It is fascinating that the word “explore” does not apply to the searching aspect of the activity, but has its origins in the sounds we make while engaged in it. We like to think of exploring in science as a lonely, meditative business, and so it is in the first stages, but always, sooner or later, before the enterprise reaches completion, as we explore, we call to each other, communicate, publish, send letters to the editor, present papers, cry out on finding.

  A FEAR OF PHEROMONES

  What are we going to do if it turns out that we have pheromones? What on earth would we be doing with such things? With the richness of
speech, and all our new devices for communication, why would we want to release odors into the air to convey information about anything? We can send notes, telephone, whisper cryptic invitations, announce the giving of parties, even bounce words off the moon and make them carom around the planets. Why a gas, or droplets of moisture made to be deposited on fence posts?

  Comfort has recently reviewed the reasons for believing that we are, in fact, in possession of anatomic structures for which there is no rational explanation except as sources of pheromones—tufts of hair, strategically located apocrine glands, unaccountable areas of moisture. We even have folds of skin here and there designed for the controlled nurture of bacteria, and it is known that certain microbes eke out a living, like eighteenth-century musicians, producing chemical signals by ornamenting the products of their hosts.

  Most of the known pheromones are small, simple molecules, active in extremely small concentrations. Eight or ten carbon atoms in a chain are all that are needed to generate precise, unequivocal directions about all kinds of matters—when and where to cluster in crowds, when to disperse, how to behave to the opposite sex, how to ascertain what is the opposite sex, how to organize members of a society in the proper ranking orders of dominance, how to mark out exact boundaries of real estate, and how to establish that one is, beyond argument, one’s self. Trails can be laid and followed, antagonists frightened and confused, friends attracted and enchanted.

  The messages are urgent, but they may arrive, for all we know, in a fragrance of ambiguity. “At home, 4 p.m. today,” says the female moth, and releases a brief explosion of bombykol, a single molecule of which will tremble the hairs of any male within miles and send him driving upwind in a confusion of ardor. But it is doubtful if he has an awareness of being caught in an aerosol of chemical attractant. On the contrary, he probably finds suddenly that it has become an excellent day, the weather remarkably bracing, the time appropriate for a bit of exercise of the old wings, a brisk turn upwind. En route, traveling the gradient of bombykol, he notes the presence of other males, heading in the same direction, all in a good mood, inclined to race for the sheer sport of it. Then, when he reaches his destination, it may seem to him the most extraordinary of coincidences, the greatest piece of luck: “Bless my soul, what have we here!”

  It has been soberly calculated that if a single female moth were to release all the bombykol in her sac in a single spray, all at once, she could theoretically attract a trillion males in the instant. This is, of course, not done.

  Fish make use of chemical signals for the identification of individual members of a species, and also for the announcement of changes in the status of certain individuals. A catfish that has had a career as a local leader smells one way, but as soon as he is displaced in an administrative reorganization, he smells differently, and everyone recognizes the loss of standing. A bullhead can immediately identify the water in which a recent adversary has been swimming, and he can distinguish between this fish and all others in the school.

  There is some preliminary, still fragmentary evidence for important pheromones in primates. Short-chain aliphatic compounds are elaborated by female monkeys in response to estradiol, and these are of consuming interest to the males. Whether there are other sorts of social communication by pheromones among primates is not known.

  The possibility that human beings are involved in this sort of thing has not attracted much attention until recently. It is still too early to say how it will come out. Perhaps we have inherited only vestiges of the organs needed, only antique and archaic traces of the fragrance, and the memory may be forever gone. We may remain safe from this new challenge to our technology, and, while the twentieth century continues to run out in concentric circles down the drain, we may be able to keep our attention concentrated on how to get energy straight from the sun.

  But there are just the slightest suggestions, hints of what may be ahead. Last year it was observed that young women living at close quarters in dormitories tended to undergo spontaneous synchronization of their menstrual cycles. A paper in Nature reported the personal experience of an anonymous, quantitatively minded British scientist who lived for long stretches in isolation on an offshore island, and discovered, by taking the dry weight of the hairs trapped by his electric razor every day, that his beard grew much more rapidly each time he returned to the mainland and encountered girls. Schizophrenic patients are reported to have a special odor to their sweat, traced to trans-3-methylhexanoic acid.

  The mind, already jelled by the advances in modern communication so that further boggling is impossible, twitches. One can imagine whole new industries springing up to create new perfumes (“A Scientific Combination of Primer and Releaser”), and other, larger corporations raising new turrets with flames alight at their tops on the Jersey flats, for the production of phenolic, anesthetic, possibly bright green sprays to cover, mask, or suppress all pheromones (“Don’t Let On”). Gas chromatography of air samples might reveal blips of difference between substances released over a Glasgow football match, a committee meeting on academic promotions, and a summer beach on Saturday afternoon, all highly important. One can even imagine agitated conferences in the Pentagon, new agreements in Geneva.

  It is claimed that a well-trained tracking hound can follow with accuracy the trail of a man in shoes, across open ground marked by the footsteps of any number of other people, provided the dog is given an item of the man’s clothing to smell beforehand. If one had to think up an R&D program for a National Institute of Human Fragrance (to be created by combining the budgets of the FDA and FCC), this would be a good problem to start with. It might also provide the kind of secondary, spin-off items of science that we like to see in federally supported research. If it is true, as the novels say, that an intelligent dog can tell the difference between one human being and any other by detecting differences in their scents, an explanation might be geometric differences in 10-carbon molecules, or perhaps differences in the relative concentrations of several pheromones in a medley. If this is a fact, it should be of interest to the immunologic community, which has long since staked out claims on the mechanisms involved in the discrimination between self and non-self. Perhaps the fantastically sensitive and precise immunologic mechanisms for the detection of small molecules such as haptenes represent another way of sensing the same markers. Man’s best friend might be used to sniff out histocompatible donors. And so forth. If we could just succeed in maintaining the research activity at this level, perhaps diverting everyone’s attention from all other aspects by releasing large quantities of money, we might be able to stay out of trouble.

  THE MUSIC OF THIS SPHERE

  It is one of our problems that as we become crowded together, the sounds we make to each other, in our increasingly complex communication systems, become more random-sounding, accidental or incidental, and we have trouble selecting meaningful signals out of the noise. One reason is, of course, that we do not seem able to restrict our communication to information-bearing, relevant signals. Given any new technology for transmitting information, we seem bound to use it for great quantities of small talk. We are only saved by music from being overwhelmed by nonsense.

  It is a marginal comfort to know that the relatively new science of bioacoustics must deal with similar problems in the sounds made by other animals to each other. No matter what sound-making device is placed at their disposal, creatures in general do a great deal of gabbling, and it requires long patience and observation to edit out the parts lacking syntax and sense. Light social conversation, designed to keep the party going, prevails. Nature abhors a long silence.

  Somewhere, underlying all the other signals, is a continual music. Termites make percussive sounds to each other by beating their heads against the floor in the dark, resonating corridors of their nests. The sound has been described as resembling, to the human ear, sand falling on paper, but spectrographic analysis of sound records has recently revealed a high deg
ree of organization in the drumming; the beats occur in regular, rhythmic phrases, differing in duration, like notes for a tympani section.

  From time to time, certain termites make a convulsive movement of their mandibles to produce a loud, high-pitched clicking sound, audible ten meters off. So much effort goes into this one note that it must have urgent meaning, at least to the sender. He cannot make it without such a wrench that he is flung one or two centimeters into the air by the recoil.

  There is obvious hazard in trying to assign a particular meaning to this special kind of sound, and problems like this exist throughout the field of bioacoustics. One can imagine a woolly-minded Visitor from Outer Space, interested in human beings, discerning on his spectrograph the click of that golf ball on the surface of the moon, and trying to account for it as a call of warning (unlikely), a signal of mating (out of the question), or an announcement of territory (could be).

  Bats are obliged to make sounds almost ceaselessly, to sense, by sonar, all the objects in their surroundings. They can spot with accuracy, on the wing, small insects, and they will home onto things they like with infallibility and speed. With such a system for the equivalent of glancing around, they must live in a world of ultrasonic bat-sound, most of it with an industrial, machinery sound. Still, they communicate with each other as well, by clicks and high-pitched greetings. Moreover, they have been heard to produce, while hanging at rest upside down in the depths of woods, strange, solitary, and lovely bell-like notes.

  Almost anything that an animal can employ to make a sound is put to use. Drumming, created by beating the feet, is used by prairie hens, rabbits, and mice; the head is banged by woodpeckers and certain other birds; the males of death-watch beetles make a rapid ticking sound by percussion of a protuberance on the abdomen against the ground; a faint but audible ticking is made by the tiny beetle Lepinotus inquilinus, which is less than two millimeters in length. Fish make sounds by clicking their teeth, blowing air, and drumming with special muscles against tuned inflated air bladders. Solid structures are set to vibrating by toothed bows in crustaceans and insects. The proboscis of the death’s-head hawk moth is used as a kind of reed instrument, blown through to make high-pitched, reedy notes.