Unraveling the DNA Myth

The Spurious Foundation of Genetic Engineering

Harper's Magazine

February 2002

By Dr. Barry Commoner

SYNOPSIS

Genetic science was founded on the discovery of the DNA double helix by Francis Crick and James Watson. In 1958, they pronounced DNA - deoxyribonucleic acid, a very long, linear molecule that is tightly coiled within each cell's nucleus - as the molecular agent of inheritance. DNA is made up of four different kinds of subunits (bases, or nucleotides), which in each gene are strung together in a particular linear order or sequence. Segments of DNA comprise the genes that, through a series of molecular processes, give rise to each of our inherited traits. Crick's hypothesis is that a clear-cut chain of molecular processes leads from a single DNA gene to the appearance of a particular inherited trait. According to Crick's sequence hypothesis, the gene's genetic information is transmitted, altered in form but not in content, through RNA intermediaries, to the distinctive amino acid sequence of a particular protein.

Tested between 1990 and 2001 in one of the largest and most highly publicized scientific undertakings of our time - the $3 billion Human Genome Project - the central dogma collapsed under the weight of face. Results published last February show that there are far too few human genes to account for the complexity of our inherited traits or for the vast inherited differences between plants, say, and people. The finding signaled the downfall of the central dogma; it also destroyed the scientific foundation of genetic engineering and the validity of the biotechnology industry's widely advertised claim that its methods of genetically modifying food crops are precise, predictable, and safe.

This should not have come as a surprise. Experimental data has been accumulating for decades. By the mid-1980s, long before the Human Genome Project was funded, and long before genetically modified crops began to appear in our fields, a series of protein-based processes had already intruded on the DNA gene's exclusive genetic franchise. An array of protein enzymes must repair the all-too-frequent mistakes in gene replication and in the transmission of the genetic code to proteins as well. Certain proteins, assembled in spliceosomes, can reshuffle the RNA transcripts, creating hundreds and even thousands of different proteins from a single gene. A family of chaperones, proper folding - and therefore the biochemical activity - of newly made proteins, form an essential part of the gene-to-protein process.

By any reasonable measure, these results contradict the central dogma's cardinal maxim: that a DNA gene exclusively governs the molecular processes that give rise to a particular inherited trait. The DNA gene clearly exerts an important influence on inheritance, but it is not unique in that respect and acts only in collaboration with a multitude of protein-based processes that prevent and repair incorrect sequences, transform the nascent protein into its folded, active form, and provide crucial added genetic information well beyond that originating in the gene itself. The net outcome is that no single DNA gene is the sole source of a given protein's genetic information and therefore of the inherited trait.

The credibility of the Human Genome Project is not the only casualty of the scientific community's resistance to experimental results that contradict the central dogma. Nor is it the most significant casualty. The fact that one gene can give rise to multiple proteins also destroys the theoretical foundation of a multibillion-dollar industry, the genetic engineering of food crops. In genetic engineering it is assumed, without adequate experimental proof, that a bacterial gene for an insecticidal protein, for example, transferred to a corn plant, will produce precisely that protein and nothing else. Yet in that alien genetic environment, alternative splicing of the bacterial gene might give rise to multiple variants of the intended protein - or even to proteins bearing little structural relationship to the original one, with unpredictable effects on ecosystems and human health.

Because of their commitment to an obsolete theory, most molecular biologists operate under the assumption that DNA is the secret of life, whereas the careful observation of the hierarchy of living processes strongly suggest that it is the other way around: DNA did not create life; life created DNA. When life was first formed on the earth, proteins must have appeared before DNA because, unlike DNA, proteins have the catalytic ability to generate the chemical energy needed to assemble small ambient molecules into larger ones such as DNA. DNA is a mechanism created by the cell to store information produced by the cell. Early life survived because it grew, building up its characteristic array of complex molecules. It must have been a sloppy kind of growth; what was newly made did not exactly replicate what was already there. But once produced by the primitive cell, DNA could become a stable place to store structural information about the cell's chaotic chemistry, something like the minutes taken by a secretary at a noisy committee meeting.

There can be no doubt that the emergence of DNA was a crucial stage in the development of life, but we must avoid the mistake of reducing life to a master molecule in order to satisfy our emotional need for unambiguous simplicity. The experimental data, shorn of dogmatic theories, points to the irreducibility of the living cell, the inherent complexity of which suggests that nay artificially altered genetic system, given the magnitude of our ignorance, must sooner of later give rise to unintended, potentially disastrous, consequences. We must be willing to recognize how little we truly understand about the secrets of the cell, the fundamental unit of life.

January 15, 2002

The article "Unraveling the DNA Myth: The Spurious Foundation of Genetic Engineering" is published in Harper's Magazine, February 2002