What language do our genes speak?
Biology as text
The American biologist R. Shapiro offers the following explanation in his report on human genome research: »We are the text generation. It has fallen to us to be the first to read the DNA text which has been amassed over billions of years and developed into the blueprint for our species.« This statement has, of course, more than a hint of that typical American pioneer spirit in the face of the unknown. But are we really the first readers of this text? If the DNA’s genetic material presents itself as a text, then it has to be made for a reader. Naturally, this text has not only existed for billions of years. It has also been read, copied and translated. That is precisely the biological function of this text.
What is genetics
Genetics is the science of differences. We only notice the hereditary transmission of a characteristic if that characteristic differentiates one individual from another. Heredity cannot be observed without this variation. And it was precisely these differences that the pea-counting monk Gregor Mendel referred to: yellow and green, round and square, white and red blossoms.
Of course, Mendel was not the first to observe the dynamics of heredity. On has always known that tall parents have tall children and those with dark hair have offspring with the same hair color. But this is not always the case and there is often a mixed result: medium-sized children with brown hair. For this reason one assumed that characteristics were somehow combined. Mendel was the first to concentrate on a single characteristic. The offspring of pea plants with red blossoms always had red blooms and those of plants with white blossoms also bloomed in white. It was only when the »pure« red and white varieties were crossed with each other that Mendel obtained the mathematically precise results that he immortalized in his principles: the principle of dominance in the first generation, the principle of segregation in the second, the principle of independent assortment.
It was a long road classical genetics to the discovery of DNA, even though it was taken in speedy strides. There were, of course, differences, but only a few. One had to makes do with what was on hand: dog breeds, hair color, blood groups. This all changed when an American geneticist by the name of Muller made an important discovery in 1929. He arrived at the conclusion that x-ray radiation could cause mutations. This allowed the number of observable changes to be drastically increased. One suddenly had a large variety of characteristics. Genetic maps could be produced listing all known genes, without knowing what these genes consisted of. Muller’s experiment with x-rays also suggested a different course for future research: the fact that a genes could alter themselves under the influence of radiation suggested the gene’s material nature.
Interestingly enough, it was the physicist Erwin Schödiger who in 1944 provided the critical impetus for the direction of further studies through his slim volume »What is Life?« If the gene had a chemical nature, then it must be the task of these gene molecules to transfer information. This had to be imagined like an aperiodic crystalline structure. By this he meant a relatively simple, that is crystalline structure which was also aperiodic, i.e. the ordered sequence includes different elements whose succession is not uniform. It is exactly like in a text (this one for example): a uniform series of letters assumes an ordered form through the lines of text. The precise order of the different letters is, however, highly irregular. This is the case precisely because information is to be transferred.
The genetic information (DNA) in the cell nucleus and is transcribed by certain enzymes (transcription). The transcribed message (messenger RNA) is transported to the cell plasma and is used as the master plan for protein synthesis (translation). This process can be illustrated using the example of a library that contains a couple of cookbooks. To save wear and tear on the cookbooks, they are not taken into the kitchen. Instead, individual recipes are copied, taken into the kitchen, and used to prepare the dishes. If a mistake is made while copying the recipes or during preparation the meal will not turn out well this one time. If, however, the cookbook contains an incorrect recipe (mutation), then the meal will never turn out. We are accustomed to mistakes generally causing failures and only rarely producing a superior result. All of evolution, in contrast, results from trying out random mistakes in recipes. An infinitely patient guest decides which recipes are good and which are simply bland. Yet another image presents itself: always eating the same food is boring! Progress in biology is the result of many small modifications. The absolutely true copy precludes all mistakes and, thus, all new experiences: perfectionism is stagnation. The language of evolution distinguishes between conformity and adaptability. It is good to be perfect in an unchanging world. In a changing one, however, one must vary the old and try out the new.
This problem also affects the newly publicized possibility of cloning mammals and thus, at least in principal, people. If we are all genetically identical, then all individual traits are solely the result of outside influences. Beauty, in such a case, comes only from nutrition and grooming (just like today’s advertising already quite frequently tries to convince us).
In their search for the nature of the gene biologists have, to their own surprise, found themselves confronted with a text. Molecular geneticists use terms like transcription, translation, genetic code to describe molecular mechanisms in the processing of genetic information. That these processes occur in the production of all texts, whether a newspaper article or a DNA text, is, however, ignored. When it was discovered that the text transcribed from the DNA could later be changed this process was called editing. This new discovery caused a great deal of surprise. It was as if something entirely unexpected had been uncovered.
Anyone who has ever turned in a text, however, knows that the editor is generally not timid in his interventions. Each text is then proofread one more time before printing. Thus, it is hardly surprising to find such a mechanism (proofreading) in DNA replication. Interestingly, it is precisely this proofreading that guarantees extremely high accuracy in the copying of DNA. Physicists, who played a decisive role in the discovery of DNA, originally considered this degree of accuracy impossible due to quantum mechanical considerations. As biologists seemed to be surprised to find that the hereditary substance DNA had something with a linguistic text, no one even considered letting language theorists tell them what this connection signified.
One can compare human language with a complex biological organ along the lines of the eye or the wing of the bird. Both resulted from adaptation in the course of evolution. That we have inborn language abilities and do not learn language through learning has been most forcefully expressed by N. Chomsky. Specifically, Chomsky pointed out the disparity between knowledge and experience. This is perhaps the most astounding fact in human language and constitutes the central problem which language theories strive to explain. What is meant by disparity is (in this case) the crass discrepancy between (as one would say today) input and output in language acquisition. Children can also learn a language in an environment where others speak very little or quite imprecisely. One knows that children whose parents only speak a mixed language (for example, Pidgin English) and that quite brokenly) themselves speak, as if it were the most natural thing in the world, a grammatically faultless form of this language. Chomsky spoke of an in inborn »Urgrammar« for this reason. This grammar would then be one of the primary human characteristics. In spite of all the loving attempts to teach our closest relatives, the apes, to speak, they have never advanced much beyond pointing to symbols for their favorite food.
If the ability to speak is biologically given and not an ability acquired through a learning process, then there has to be a gene for grammar. In searching for these genes geneticists look for examples of grammatical »mutants.« There are actually speech defects that are passed down in families according to Mendel’s principles. J. Maynard-Smith of the University of Sussex cites the example of a grammar deficiency that appeared in 15 out of 24 family members. Although the carriers could implement some rules, they could only do this after learning each individual case separately. They lacked the ability to generalize when faced with particular forms. It is precisely this ability which enables us to compose an unlimited number of new, never before heard, but nevertheless grammatically correct sentences. According to geneticists one or, more probably, many genes are responsible for language ability. It can be assumed that these genes somehow participate in brain development. This does not, however, make the search for these genes any simpler, knowing as we do that a large number of genes are involved in the development of the brain.
Words in the Genes
In view of the complexity of the protein structures produced in the biological system the probability of their spontaneous emergence seems practically impossible. Geneticists often use an analogy to illustrate the minimal likelihood of such a scenario: an ape randomly pounds on the keyboard of a typewriter and – if given a sufficient amount of time – just happens to produces all of world literature including the dramas of W. Shakespeare. By trying to figure out how much time the ape would require just to produce the sentence »To be or not be, that is the question,« one can recognize what an apt analogy this is for the duration of eternity. Incidentally, this ape already appears in one of David Wilhelm Triller’s poems (»The ape, an odd printer«): the ape believes that by merely tossing the letters about » here with great luck / and little effort to print / Should this be called printing? / To throw letters on paper/ produces not a learned book / Toss them about for a hundred years and more / and still not one clever word is took.«
In some case one actually hits pay dirt by taking nature quite literally and looking for these clever words in her gene sequences. The currently known amino acid sequences may not include Shakespeare’s dramas, but a few important discoveries can nevertheless be made. The abbreviation of The Word Company (TWC), for example, can be found in the neurotoxin of a central Asian cobra. The word-creator Fricke himself appears—coincidentally?—in the sequence of a brain carrier and one of his favorite words, MIPSEL is actually part of an ABC (!) transporter.
Neurotoxin: a poisonous substance that specifically inhibits the transmission of nerve signals and, thus, can cause paralysis, etc.
Brain carrier, mitochrondrial: a protein which carries out the transport of certain substances from the brain cells to the mitochrondria (cell organelles)
ABC transporter: a membrane protein that transports substances through the cell membrane and contains an ATP (adenosintriphosphate) binding cassette
Prof. Dr. Michael Bölker teaches Genetics the Universität Marburg. For more information on biology and genetics you may start with the »BioLinks« of the Harvard University.
© 1999 Michael Bölker & Adib Fricke, The Word Company.