by Guy Murchie
RNA's main job is manufacturing protein, because proteins are the common molecules of life, providing not only the substances of blood, muscle, bone, nerve, etc., but also acting as the mobile chemical intermediaries or enzymes so indispensable to practically all life's physical processes. Every cell indeed, just to stay alive, has to be continuously and simultaneously grinding out hundreds of different models of protein. And a bacterium, which will sometimes reproduce itself in 20 minutes, may fabricate and distribute any of 1000 different kinds of protein in that short time, most of them enzymes geared to turning out membranes, ribosomes, mitochondria and hundreds of cell details, each in its proper sequence relative to the others. Protein in all its variations is the same miraculous molecule we have been describing as a long complex chain made up of twenty kinds of amino acids, each protein being a particular combination of them.
When DNA makes RNA it evidently unwinds its double strands and invites in complementary nitrogen compounds, etc., from the surrounding medium, as if replicating itself, but it does it somewhat differently (accepting more oxygen atoms for one thing) and so many kinds of RNA stream out of DNA - some conveying messages, some acting as brokers - that I couldn't possibly describe or explain them, even if I knew how.
The place where all this happens and where proteins are manufactured is inside the ribosomes, those thousands of globules floating like submicroscopic cherries about the cytoplasm just outside the cell's nucleus (page 104). It is not yet known exactly how each ribosome receives its RNA messengers when they arrive from the nucleus, but we can deduce that it does so somewhat as a player piano receives a roll to play a tune with. At least there is no doubt that the ribosome "reads" the RNA tape and "learns" the message, which it then expresses in a sequential production analogous to playing music. But naturally this abstract melody of life is not literally heard. Perhaps it is physically more analogous to the linotype already mentioned, since it produces the long polypeptide chain molecules we know as protein. And it is known that the ribosome scans the messenger-RNA with the close assistance of so-called transfer-RNA in precise sections: three chemical rungs at a time.
Such a section of code is called a codon and it corresponds to a three-letter "word" written in the four-letter RNA alphabet: A, U, C, G. The codon may be AUU, for instance, which specifies the amino 170 acid tyrosine, or UUU which means another, called phenylalanine. Sixty-four different three-letter combinations or "words" are possible in this alphabet, far more than ample for designating all the 20 amino acids. The codon is inspected somehow by the little transfer-RNA brokers, who continuously bustle about the ribosomes searching for the combinations that represent their clients, like schoolboys looking for their family names on a bulletin board. Each broker holds the complementary half rungs of three letters that stand for one particular amino acid, probably reading the successive codons by the Braille method, literally feeling the raised "letters," testing each codon until (by trial and error) he finds the one in twenty that fits - and so gives life its form and substance.
But this genetic code or DNA-RNA language in which specifications for all living systems are written with only four letters and a maximum of 64 three-letter words is neither as simple nor as foolproof as it appears. This is shown partly by its mutations or "typographical errors" during transmission, which, while at first they seem to be accidents, from the broader viewpoint of evolution and the long-term need for new species to cope with changing environs, are eventually revealed as vital factors in the way of life. Like other "accidents" mutations are individually much more likely to be destructive than constructive, for the same reason that hitting a balky watch with a hammer at random hurts it thousands of times more often than it helps it. Yet out of many thousands of mutations, inevitably a rare one now and then will bring a beneficial attribute: perhaps an unprecedented capacity to tolerate a drastic drop in temperature that, at the onset of the next ice age, will enable the species that received it to survive. And it is just such rare helpful mutations that lend life its vital flexibility.
Another remarkable thing about mutations is that they gain their effect on evolution in a subtle, cumulative way that until recently escaped notice. Mutagenic changes, as I have said, are much like misprints in the typed page of a manuscript, misprints that might be made by a typist who averages one error every time she types a page of 2000 letters. Such a rate may be considered reasonably low or normal. Yet if the typist starts with a perfect copy and keeps copying it perfunctorily without thinking of its sense or correcting mistakes, each time copying her latest copy, including its latest misprint, by the tlme she has finished the thousandth copy it will contain something like 800 errors (allowing for errors in copying errors which, in rare instances, actually correct them) and the page's meaning will have become unrecognizable. That is about how DNA copies itself, automatically and blindly, cell division by cell division, mutation upon mutation, generation after generation, and how even the lowest mutation rate will in time transform and evolve life.
Although the genetic code has been deduced mainly from studies of the colon bacillus or bacterium living in our intestines, it appears to be a universal code, at least as far as the earth is concerned, applying equally well to every organism from tobacco plants to human beings. Cracking the code may turn out to have been the most important scientific accomplishment of the twentieth century, surpassing the dissection of the atom and its nucleus or the dramatic conquest of space, for its potential consequences in eugenics and evolution are incalculable. It was done by the coordinated efforts of thousands of researchers in dozens of nations, progressively fitting together the pieces of evidence, mapping genes and mutations, rendering amino acids radioactive one after another to trace their separate movements and deduce their individual parts in genetic function.
THE ABSTRACT ASPECT
The abstract nature of life is made clearer as we study the gene, for it becomes obvious that the gene is essentially a catalyst, not a creator, materially speaking. Indeed when parents create a child, they do not create substance out of nothing but use the material of their environment, only giving it a genetic key or direction for growth, a pattern for synthesis, an abstraction. The atoms that form the child are any old atoms of the earth that just happen to be passing through the mother's body as the child needs and absorbs them - and the essence of the child is in its genes, the mysterious blueprints of growth and development, of physical, mental and spiritual unfoldment. In fact there isn't a very fundamental difference between mixing inorganic cement in a cement mixer and mixing organic cement in one's digestive system. Either way, one takes available stuff from one's environment and, through a mixing or stirring process, builds one's abode with it, shaping the masonry into walls or bone or hive or shell or flesh as occasion requires.
In some sense, I have little doubt, genes know what they are doing, for they are memory incarnate, letters of living purpose, the script of life in a material universe. Stretching my imagination a little, I can think of them as grains of mind or even psychic feathers or scales, as veritable units of thought "made flesh," as St. John put it, to "dwell among us" or, if you like, as the flowing texture of mortality metabolizing its body in space and time. And a gene is not necessarily bounded, even abstractly, for it amounts to a composed pattern of simpler units, each of which subtly interacts with its sister genes on either side, so that not only may a given gene have several effects but an effect may come from several genes. Furthermore there are genes that control other genes and a few that trigger disintegration and death in ostensibly temporary opposition to growth and life, thus showing death to be, biologically speaking, a detail of life.
Interestingly also, genes have been found to have the material molecular structure of aperiodic crystals and it is thought that they very probably evolved in the same basic way as other crystals, which are well known to be the structural basis of rock, as well as of wood, bones and flesh. And this may explain not only why radiolarians in the sea seem to have a
bout as many thousands of species as there are possible geometric structures to hold them together, but also why there are "genes" of a sort in snow crystals, their rarely seen nuclei being the microscopic dust particles or germs that the ice forms around and whose countless variations in shape logically account for the illimitable "species" of snowflakes, as suggested by D'Arcy Thompson in On Growth and Form in 1917.
These concepts of course more or less transcend the material aspect of life and the body, which have been the subject of Part One. Indeed they introduce an abstract quality into this book that naturally leads us to the intangibilities of Part Two. And that is where we may hope to discover that life's range of senses is wider than man has been aware of until now - also where human vision may be permitted a peek into an invisible mirror, deep within which, if we are fortunate, we may hope to see - what else? - the mind.
Part Two
MIND
Chapter 7
Eleven Senses of Radiation and Feeling
* * *
IT IS SURPRISING that we so rarely feel lonely out here in space. In my case, it may be only because I am more than normally aware of being a family member of the universe. In others, it often seems something else, perhaps in a way like being on the stage. If that idea is puzzling, may I remind you that we here have completely relinquished the sheltering rondure of the globe, each point on which is hidden from every other point except its immediate neighbors. And our resulting loss of privacy makes this station a kind of celestial goldfish bowl, indeed a habitation that is in the direct line of sight of more and more people the higher we go. Furthermore, the station's resemblance to a stage is striking, as our eyes are dazzled by the unfiltered spotlight of the sun, the lesser glare of the moon and the footlights of planets and stars, while everywhere before us, below and above, yawns the black void of an unseen audience whose true gamut of feelings we can hardly begin to surmise.
If the challenge of our view from space is basically a challenge of mind, this first page of Part Two is the place to mention it. Here we leave body to start our investigation of mind, which, even more than body, is a criterion of life. Besides, as mind's interaction with body must come primarily through the senses, these next two chapters on sense will serve, I hope, as a fair introduction to mind.
In any case, while now and again some susceptible astronaut may experience something akin to stage fright on his debut here, they all get more or less used to it and most of them seem to enjoy the stimulus of the unearthly sensation. I call it a sensation rather than a sense but, come to think of it, I wouldn't be surprised if it eventually evolves into a new sense. Certainly it adds something to the remarkable spectrum of senses already known on Earth.
A lot of people seem to think there can be none but the five traditional senses of sight, hearing, smell, taste and touch. In a way they are right, I suppose, if you assume that only the ones most obvious to humans are to be included. But surely there are more senses in Heaven and Earth than you or I have dreamed of. And I have increasingly had the feeling that the time has come when someone should pioneer into the subject as a whole with a fresh, untrammeled outlook. So, out of more than idle curiosity, I've jotted down a list of all I could think of and it came to 48, not even counting the stage-inspace "sense" previously described. Then, by combining the most closely related ones, I trimmed the number to 32. Of course a lot depends on how one defines a sense, and on arbitrary choices, like whether you decide to lump the sense of warmth and coolness or the sense of dryness and dampness in with the sense of feeling, and whether you want to include the senses (or are they instincts?) that animals, plants and (conceivably) rocks have but most humans evidently don't.
Here is my list of the principal senses of all creatures:
The Radiation Senses
1.Sight, which, I should think, would include seeing polarized light and seeing without eyes, such as the heliotropism or sun sense of plants.
2.The sense of awareness of one's own visibility or invisibility and the consequent competence to advertise or to camouflage via pigmentation control, luminescence, transparency, screening, behavior, etc.
3.Sensitivity to radiation other than visible light, including radio waves, x-rays, gamma rays, etc., but omitting most of the temperature and electromagnetic senses.
4.Temperature sense, including ability to insulate, hibernate, estivate, etc. This sense is known to have its own separate nerve networks.
5.Electromagnetic sense, which includes the ability to generate current (as in the electric eel), awareness of magnetic polarity (possessed by many insects) and a general sensitivity to electromagnetic fields.
The Feeling Senses
6.Hearing, including sonar and the detection of infra- and ultrasonic frequencies beyond ears.
7.Awareness of pressure, particularly underground and underwater, as through the lateral line organ of fish, the earth tremor sense of burrowers, the barometric sense, etc.
8.Feel, particularly touch on the skin and the proprioceptive awareness of intra- and intermuscular motion, tickling, vibration sense (such as the spider feels), cognition of heartbeat, blood circulation, breathing, etc.
9.The sense of weight and balance.
10.Space or proximity sense.
11.Coriolis sense, or awareness of effects of the rotation of the earth.
The Chemical Senses
12.Smell, with and beyond the nose.
13.Taste, with and beyond the tongue or mouth.
14.Appetite, hunger and the urge to hunt, kill or otherwise obtain food.
15.Humidity sense, including thirst, evaporation control and. the acumen to find water or evade a flood.
The Mental Senses
16.Pain: external, internal, mental or spiritual distress, or any combination of these, including the impulse and capacity to weep.
17.The sense of fear, the dread of injury or death, of attack by vicious enemies, of suffocation, falling, bleeding, disease and other dangers.
18.The procreative urge, which includes sex awareness, courting (perhaps involving love), mating, nesting, brooding, parturition, maternity, paternity and raising the young.
19.The sense of play, sport, humor, pleasure and laughter.
20.Time sense and, most specifically, the so-called biological clock.
21.Navigation sense, including the detailed awareness of land- and seascapes, of the positions of sun, moon and stars, of time, of electromagnetic fields, proximity to objects, probably Coriolis and other sensitivities still undefined.
22.Domineering and territorial sense, including the capacity to repel, intimidate or exploit other creatures by fighting, predation, parasitism, domestication or slavery.
23.Colonizing sense, including the receptive awareness of one's fellow creatures, of parasites, slaves, hosts, symbionts and congregating with them, sometimes to the degree of being absorbed into a superorganism.
24.Horticultural sense and the ability to cultivate crops, as is done by ants who grow fungus, or by fungus that farms algae (page 72).
25.Language and articulation sense, used to express feelings and convey information in every medium from the bees' dance to human literature.
26.Reasoning, including memory and the capacity for logic and science.
27.Intuition or subconscious deduction.
28.Esthetic sense, including creativity and appreciation of music, literature, drama, of graphic and other arts.
29.Psychic capacity, such as foreknowledge, clairvoyance, clairaudience, psychokinesis, astral projection and possibly certain animal instincts and plant sensitivities (page 308).
30.Hypnotic power: the capacity to hypnotize other creatures.
31.Relaxation and sleep, including dreaming, meditation, brainwave awareness and other less-than-conscious states of mind like pupation, which involves cocoon building, metamorphoses and, from some viewpoints, dying.
The Spiritual Sense
32.Spiritual sense, including consc
ience, capacity for sublime love, ecstasy, a sense of sin, profound sorrow, sacrifice and, in rare cases, cosmic consciousness (page 591).
To sum up, I've grouped these senses into five categories. First, the radiation senses (1 - 5), which include not only vision and electromagnetism but temperature awareness because that comes from infrared radiation. Second, the feeling senses (6 - 11), including not only touch and pressure perception but hearing because that means "feeling" the pressure of successive sound waves vibrating in the ear. Third, the chemical senses (12 - 15), which encompass not only smell and taste but hunger and thirst because these are largely controlled by the chemistry of the body. Fourth, the mental senses (16 - 31), which appear to develop mostly in the mind, among which are included a few like the urge for procreation and the navigation instinct which generally involve several other senses, not to mention having variations roughly in proportion to the number of species using them. And finally the spiritual sense (32), which is presumably newly evolved and appreciably developed only in man.
It is perhaps more than we should have done even to try to enumerate these thirty-two senses - for obviously they overlap a good deal, are often controversial, arbitrary, ambiguous and vague, if not ill defined. And many of them could, with fair justification, be termed instincts or capacities rather than senses. But it seems to me useful to list them, if only to demonstrate the complex nature of the broad subject of sense and whatever other channels there may be by which the mind relates to the body.
Since all these senses evidently arose during the past few billion years of earthly evolution, it seems expectable that more will evolve in the earth's next few billion years - and indeed that some must be in process of evolving now, presumably the kind often referred to as occult or "sixth" senses, because they are mysterious, immeasurable or found only in a few rare or divinely endowed individuals. All the senses, I would think, have passive and active aspects. I mention the passive first because that is usually the better known. It is the reception by eyes, ears, noses, etc., of radiation, of vibrations, of particles sent forth from elsewhere. But the sources of these waves, emanations or messengers and the source viewpoints are vital factors to the senses too of course, and they are the active end of the sense exchange, which often amounts to a throw-and-catch feedback.