The Mystery of the Libidinous Molecule

Nobody can accuse the great pioneers of molecular biology of being mere Ivory Tower specialists, unwilling to emerge from their laboratories to tell us their thoughts about the general significance of the advances in our understanding of living systems which their work has brought about. Salvador Luria, who in 1969 shared a Nobel Prize for his part in “The Virus Group” which laid so many of the foundations of molecular biology, is the latest in a line that includes Francis Crick, James Watson, Jacques Monod, and François Jacob. In a review of the books of the last two, I distinguished between “hard-line” and “soft-line” biologists. Monod, I suggested, belongs to the former type, Jacob tends toward the latter. Both are, of course, “materialists” in some sense of that obscure word, but the hard-liners give the impression that it is enough to say that “life is a molecule is a molecule is a machine”; the soft-liners sometimes allow themselves to express a certain hesitancy in the face of questions about such aspects of biology as evolution and goal-seeking behavior, let alone about such topics as values or the mind.

The merit of Luria’s book is that he leans sufficiently toward the soft end of the spectrum to feel called upon to approach the major problems of general biology in a more open-minded manner than the hard-liners find necessary. One has only to read a few pages to get the impression that the author is well read, civilized, sincere, inquiring, neither cocksure nor doctrinaire; a thoroughly nice guy. But the core of any criticism there can be of the book is that it is perhaps a bit too nice to be really good. After all, that title: “Life: The Unfinished Experiment”? A trifle inspirational perhaps, though not nauseatingly so. But is life an experiment? An experiment is designed by someone to answer some question. That isn’t what Luria means about life; he really thinks of it as a happening. For instance we find: “As recently as the turn of the twentieth century…the Western world expected a continuous if uneven transition to an era of peaceful progress. Two world wars and several genocides later mankind stands appalled at the capacity for mischief that has been developed.” Capacity for mischief—I ask you!

Of course such verbal infelicities are trivial compared to the serious points of Luria’s discussion. He brings out clearly many of the more recent insights into the nature of living things, which go beyond the orthodoxies of thirty years ago. For instance, he realizes that life must be discussed in terms which imply that activity is essential. It has been conventional to speak of life as a system of handling “information,” that word being used in the technical sense in which it means a measure of the difference between things. Luria states that “life is distinct from all other natural phenomena in one feature; it has a program.” And a program is a set of instructions to perform a series of actions.

Luria makes a series of points about evolution which we have only in the last few years come to realize are of crucial importance. In the first place, “Selection does not act directly on the genes; it works on phenotypes, on the complex of the actual characteristics of the organism.” This principle, which is obvious enough once it has been stated, should be sufficient to rescue one from the abstract world of genes and their associated selective values in which the mathematicians of thirty years ago tried to confine evolutionary thinking. And Luria goes on to acknowledge that man, by his development of culture and particularly of language, has forged for himself a new instrument for evolution, which allows him to pass on programs to his offspring not merely in the biological form of genes but in the super-biological form of verbal instructions.

In this way Luria provides himself with a powerful all-round armory of concepts. With them he is bold enough to tackle the most redoubtable riddles of the sphinx of biology. Mind, Purpose, Value, Free Will—he is not afraid to enter the lists against any of them. One cannot but applaud his courage, and his performance also earns at least some applause. His conclusions are always sensible and honorable—by which I mean, I suppose, not much more than that they are similar to my own. What I doubt is whether he has made the best case possible for them. He has armed himself with these ideas; does he always fully understand them and how they may be used? It may be doubted.

Luria lays less stress than most of the other eminent molecular biologists on the importance of biology being molecular. Occasionally he makes remarks such as, “Genes are merely molecular structures,” as though that put them firmly in their place, as crudely mechanical. In fact, of course, what the molecular biologists have shown is that biological systems depend on the activities of structures—DNA, RNA, protein, and so on—which are very unlike the molecules we knew of in the past. Some of their little habits, essential for the functioning of life, would bring a blush to the cheek of the most hard-nosed Herr Professors whose corporate wisdom constituted the definition of a molecule at the beginning of this century. Even if we choose to call them macro-molecules, these newcomers behave in ways more suitable to randy teen-agers. Tickle one sensitive site on their surface—lip or tit—and another sensitive site—prick or cunt—opens up ready for action. To call them molecules is not to tell anything new about them; it is merely to indicate that we have decided to use the word molecule to mean “the active pieces the world is made of,” whatever those pieces may turn out to be.

It is in the context of evolution that Luria is left most exposed by his agreeable habit of following the new ideas only as far as is nice, but not to the lengths at which they turn nasty toward the older notions. As he says, “The dualism of the material nature of life’s program on the one hand and the historical nature of biological evolution on the other hand is the leit-motif of this book.” So it is of crucial importance that when he comes to a crucial point he retreats to the old mechanist position.

Conscious activity is the assertion of freedom because thereby does the self grow. Here I approach the central dilemma of life science. The essence of biology is evolution, and the essence of evolution is the absence of motive and of purpose.

The last clause is sheer old-fashioned dogma. No one looking at living systems as they exist in nature can fail to notice that the evolutionary forces (such as natural selection) at work on animals are considerably, and in higher animals predominantly, determined by the ways in which the animals behave; and behavior can legitimately be considered as controlled by motive and purpose, provided that we are willing to use those words simply to describe a character which some activities may exhibit rather than as necessarily implying conscious feeling.

As convincing a collection of evidence about this state of affairs as one could hope for can be found in another recent book by a Nobel Laureate biologist. Karl von Frisch’s field of work lies at the opposite pole of biology to the molecular. He is the founding father of the study of the behavior of animals along the lines which have come to be called “ethology.” Perhaps his best-known work is that in which he describes a method of communication, possibly worthy of being called a language, by which a bee which has found a favorable supply of food can convey to his hive mates the direction in which it lies and its distance.

In his present book, written in collaboration with his son, he provides a comprehensive survey of all the types of construction made by animals. They mostly serve as dwellings or places in which to rear young: bird nests; nests of ants, wasps, bees, termites; marmot burrows, beaver lodges, and so on. A few are more like pieces of equipment, usually for hunting, such as spiders’ webs, or the funnel-shaped fishing nets woven by some caddis fly larvae to catch little edible creatures drifting past in the water. The variety of structures, as von Frisch pictures them in drawings and in some remarkably clear and beautiful photos, is almost incredible. It will be a surprise to many to realize that it is not only evolutionarily advanced animals like birds, mammals, and some higher insects that can build. Even simple single-celled animals construct shells for themselves out of things like sand grains; and many worms and similar lowly animals can exhibit remarkable skill.

There, of course, the tricky question has crept out into the light, as it is bound to do, and sooner rather than later. In continuation of the earlier argument about evolution, one must, I think, grant that the ability of animals to construct the places they live in, and thus influence the character of the natural selection they will submit to, makes it completely inadequate to discuss evolution in terms of what Luria speaks of as “Monod’s formulation, chance and necessity are the two faces of biological progression”—which Luria accepts. But is it in any way allowable to use a word like “skill” in this connection? And if so, just how is it being used?

When Luria mentions the question, he writes as though he feels it is adequately dealt with by a reference to “instincts.” He describes the elaborate mating behavior of birds like doves, but concludes, “The charming romance is fully stereotyped, entirely inscribed in the genetic make-up of the species.” Von Frisch, who knows the facts, which are his own field of study, much more intimately than would be possible for Luria, is more equivocal. In one place he writes:

With the bird we feel the eye to be the mirror of a mind, like the human eye. Therefore, many people are inclined to believe that birds approach their nest-building with reason and foresight. But, in fact, bird’s activities are also ruled by instinct, even if learning and individual experience do play a role in guiding their actions.

But when he comes to details, he describes many instances of behavior, from many groups of animals, which force one to ask just how much illumination one gets by attributing an activity to an instinct. After all, when Kingsley Amis wrote a novel about a man whose behavior was “instinctive” to the extent that merely reading the phrase “Girl 20” in the classified ads put his fly under tension, this did not leave the author with nothing further of interest to tell about him.

It may be true, as far as it goes, to say that each species of weaverbird has an inherited instinct to build a nest of a particular pattern, some round with a short entrance, others pear-shaped with a long entrance tube hanging down like an empty stocking; but is that enough to satisfy us as an account of what the bird actually does when it approaches a half-built nest with a new piece of dry grass in its beak and has to weave this in and out between the existing strands to produce a firm structure in the “instinctive” pattern? Actually we know that some weaverbirds build better nests in their second year than they did in their first. Presumably they learn from experience, which must mean that not all the details of their performance are controlled by their heredity, but some can be adjusted to suit the circumstances.

Von Frisch describes many other examples in which it seems impossible to avoid the conclusion that the animals are carrying out some over-all inherited purpose but also have considerable latitude to adapt their behavior to the existing circumstances so as to achieve their goal. What about, “In the hot volcanic areas of Salerno in southern Italy, bees were observed mixing propolis [resin] into the wax they used for building in order to raise its melting point”? In order to? What else can one say? Or consider the skill with which bees measure the thickness of the wax walls of the cells they are making and either pare away surplus material or spread more to achieve a thickness of 0.073 millimeters (0.094 mms. for drone cells), with a tolerance of no more than 0.002 mm. What truly astounding precision, as von Frisch remarks.

Or consider the termites who build large nests which not only contain living quarters for the termites themselves but also fungus gardens for their form of agricultural food production, and also have elaborate ventilation systems. There are local traditions directing how the ventilation should be arranged; termites of the same species adopt different systems in Uganda and the west coast of Africa. And “meaningful reactions to extraordinary situations, or what one might call emergencies, have been observed. When a termite mound was enveloped in a plastic tent so that ventilation was seriously impeded, the termites managed within forty-eight hours to build new structures at the top of the mound, which looked somewhat like small pointed hats and had exceptionally porous walls so that they functioned as a new ventilation system.”

Some birds can be even cleverer. I think my favorites are the Australian Megapodes. They get together a mound of leaves, which rise in temperature as they rot down to compost; the eggs are laid in a hollow on the top, and are covered with just the right thickness of sand, carefully adjusted morning and evening, to remain at the right temperature in a balance between solar heat and that of fermentation. One feels that those creatures lucky enough to live in volcanic regions, where the soil is warm, so that they merely choose the right place to put their eggs, are really cheating.

What can one do to connect these astonishing performances with even the most tricky and macro of molecules that the biochemists have been able to think up? In the first place, I think one must be content to leave consciousness out of it. All that we can ever know about the conscious experience of another being is what that being can communicate to us; and in the absence of a mutually comprehensible language, that is little indeed. There is no firm assurance that those libidinous molecules do not feel ticklish when they are being activated, but if they do, we have no way of knowing about it.

What we can discuss is the goal-seeking character of so many of these behaviors. We can describe the actors as exhibiting a purpose, even if we cannot meaningfully ask whether the purpose is a conscious one or not. The extraordinary fact about these purposes is that they seem to be determined in their general nature but not in their details. The weaverbird has little scope for individuality in the shape of the nest it finally achieves but is free to decide how to plait in the next strand of grass in the light of the immediate set-up. It is difficult at present to see how to explain this control of global rather than detailed characteristics in terms of our usual theories of elementary active units, such as genes. There is a similar difficulty in embryology; a lump of tissue in an embryo may become fixed to develop into the foreleg as opposed to the hind leg before any part of it is determined to become a finger rather than the elbow.

In the field of behavior, there are other phenomena which are even more puzzling. Many of the most impressive structures built by animals are produced not by individuals but by societies. An individual termite or ant seems not able to perform any sensible-looking building activity; it is only when quite a number of them get together that they produce the elaborate and well-planned communal nests.

This is one of the themes around which Lewis Thomas has written some of the short and delightful essays of The Lives of a Cell. He reminds the general reader of many fascinating aspects of biology which have tended to be overlooked in the dazzlement surrounding molecular biology. One of his main ideas is the importance and the mysteriousness of social behavior among animals of all kinds. In fact, he reminds us that we ourselves are in some way societies and not merely individuals. We are made up of cells, each somewhat distinct; and further, each cell contains smaller structures, such as mitochondria, and these appear to have originated from bacteria, which at one time could have lived in isolation, and would have to be regarded as separate individuals. But they have, through long periods of evolution, become so fully incorporated that they could not exist in isolation, and neither could the cell maintain itself without them. Our unity as individuals is not quite so assured as we commonly think.

Just who or what is carrying out these goal-seeking activities: a simple individual; an “individual” who is really a conglomerate of subcellular parts which, at some stage of evolution, were separate individuals; or a society of individuals? It would be nice at this point to produce a neat answer to these riddles, but the last word really remains with von Frisch: “One can try circumlocution with learned words, but I think it is better to say, quite simply, we do not understand.”