Figure and Ground -- We've Known This All Along

Of all this, little is really news. A randomly chosen recent issue of Nature will probably contain some equally devastating counter-argument to simplistic claims about DNA information. Nor are these all recent findings. The history of molecular biology contains a long list of dissenters from the DNA orthodoxy. Barbara McClintock, for one, saw early that there were regulatory functions to DNA, and that the picture was considerably cloudier than the one painted by the mainstream³⁵; David Nanney presented findings about non-genetic inheritance in Paramecia at some of the same conferences at which DNA function was being hammered out³⁶; Robert Rosen pointed out logical inconsistencies in the use of information in the context of genetics in papers published in the early 1960's³⁷; J. Chayen, Alfred Hershey and several others insisted, during the 1950's, that the available evidence showed only that DNA could carry genetic information, not that it was the only such possibility³⁸; D. Wilkie published an extensive monograph in 1964 outlining all the evidence that cytoplasm could influence heredity³⁹; and the British embryologist C.H. Waddington, throughout his career, provided both examples of development unexplained by the standard interpretation⁴⁰, and a compelling synthesis demonstrating how little help conceptions of "information" could be in solving the real problems of biology.⁴¹ There were many others.

As the field progressed, and the standard interpretation became elaborated, many, though far from all, of these objections eventually came to be explained by known features of gene function. Some, of course, took longer than others. McClintock's deduced the existence of genetic "transposable elements," which are now well known and commonly referred to as "transposons." Many of Wilkie's and Nanney's observations have been explained by the discovery that cellular elements (such as mitochondria) can have their own DNA, and therefore their own genetic effects. But many of these observations remain untouched by the current understanding: the organization of McClintock's transposons, and the genomic reactions to environmental stress; the inheritance of acquired traits noted by Nanney; and the "canalization" described by Waddington all remain firmly beyond the explanatory ability of current genetics.

Though data was available at the time that can now be seen as troubling to the central dogma, it was ignored by those eager to embrace the new, simplifying, theory of the role of DNA. But even the objectors could see the appeal of the new ideas, as well as the lay of the land. Alfred Hershey, whose own experiments with Martha Chase had done so much to promote the idea that DNA carries genetic information, said in 1953 that none of the available evidence "forms a sufficient basis for scientific judgement concerning the genetic function of DNA."⁴² He followed up with these words:

The evidence for this statement is that biologists (all of whom, being human, have an opinion) are about equally divided pro and con. My own guess is that DNA will not prove to be a unique determiner of genetic specificity, but that contributions to the question will be made in the near future only by persons willing to entertain the contrary view.⁴³

Fifteen years later, Chargaff put it this way: "DNA, a hundred years ago a humble molecule in Miescher's hands, has been hypostasized into one of the symbols of the ever-increasing divorce from reality that characterize our living and thinking."⁴⁴ That is, thirty-three years ago, he was already tired of hearing about organisms being nothing more than abstract "information."