Comet With a Cold

I was once visited by a science writer who told me in a state of some excitement of a notion to which he attached great importance: suppose a brain to be transplanted from one person to another; would not the new identity of the recipient of the graft raise perplexing, disturbing, and very likely insoluble legal and personal problems?

I did my best to explain why the brain could not be transplanted, calling in evidence both its extreme susceptibility to being deprived of oxygen, and the mass of evidence accumulated during the war pointing to the slowness and functional inadequacy of the healing of even quite simple and clean lesions in peripheral nerves—inadequacies that would be multiplied a thousandfold in the transplantation of the brain.

The writer listened attentively to my arguments and then rejected them all. He was in love with his idea and no amount of reasoning could disenchant him. I do not know whether his intended article or book was ever written, but if it was it would have been a serious rival to the book currently under review as the silliest and most unconvincing quasi-scientific speculation yet put before the public.

One of the authors of Diseases from Space is a famous astronomer, the other an applied mathematician. Neither, then, is a biologist, although they wrote together an earlier book, Lifecloud, claiming that life arrived on earth from interstellar space. They write on biological matters in a style more confidently asseverative than that of any professional biologist known to me. A sentence such as “the most important quality of biology lies in its ability to increase numbers explosively” is to my way of thinking barely literate. The same goes for such a statement as “harmful bacteria seek to multiply their numbers uncontrollably.” I don’t think much of the title, either. It is not diseases, but disease-causing agents such as bacteria and viruses that land—or as I believe do not land—on the earth from outer space. During the greater part of the book the authors grapple with the possibility that various disease-causing agents reach us from outer space—though in places (e.g., page 4) they entertain the less farfetched hypothesis of their earlier book that it is only “life-forming materials” that rain upon us from the outside.

At a fairly early stage in the book the authors call attention to the extreme specificity of viruses in relation to cells whose synthetic machinery they subvert.

This raises the question of how a virus that evolved in some place other than the Earth could have become equipped with the ability to attack cells here on the Earth. The question is sharpened by the fact that specific viruses only attack specific kinds of cell. How, one may wonder, could a virus coming from a comet have foreseen the kind of living cell it was going to encounter after its arrival here on Earth?

The authors set their misgivings at rest thus:

There is obviously no direct answer to this question, but a decisive answer can be reached by turning the question around. The invading virus cannot know in advance about its terrestrial host, but the host can know about the virus, for the reason that terrestrial host cells have had a vast experience of invading viruses, an experience extending back in time over thousands of millions of years.

In essence the argument is that viruses can get here because they have been here before—an excellent example of petitio principii, as they used to say in ancient Rome.

The discussions of epidemiological matters struck me as the worst in the book. For example, the ambition to rid the world of infectious disease is illusory, we are told. WHO claims to have rid the world of smallpox, “but the world has been rid of smallpox before.” (Now, when was that? The authors’ claim that it was “apparently unknown to Classical Greece and Rome” is hardly an answer.) The likelihood, then, is that smallpox will come again,^* arriving deep-frozen in comets.

It is a corollary of the authors’ views that human beings must in the past have been afflicted by diseases of which we have no present knowledge. Indeed, “An astonishingly virulent and remarkably localized disease struck the city of Athens in the summer of 430 BC”—a disease with symptoms “unlike anything known to modern medicine!” But Thucydides’ description which the authors quote and commend for its clarity was of a severe febrile disease, with vomiting and a variety of upper respiratory symptoms, accompanied by severe headaches, convulsions, extreme thirst, sleeplessness, and apparently a degree of paresis. A severe viral infection with encephalitic complications is a more likely explanation of these symptoms than a visitation from outer space.

Epidemiological considerations lead the authors to question whether the common cold and influenza are indeed infectious in character—that is to say, they question the widely prevalent notion that the causative agents may be propagated from one person to another. The authors believe that person to person transmission would be too slow to account for the sometimes pandemic character and speed of onset of so many outbreaks of influenza and the common cold. These phenomena are much more easily explained, they believe, by a fallout of virus from the atmosphere. The authors do not give adequate attention to the various factors that effect the transmission from person to person of disease-causing agents. One such factor is the varying degrees of pre-existing acquired immunity, and a second is the existence of inborn differences in susceptibility to bacterial and viral diseases. Arguments that do not give these factors adequate weight are sure to be misleading.

The authors supply several appendices, including one containing commonplace information, easily obtainable elsewhere, on the storage and recall of genetic information. This may con the inexpert reader into believing that this book has a special biological authenticity. I must therefore record my view that the book is tiresome and unconvincing throughout: it need not have been written or, written, need not have been published.