Virolution. Frank RyanЧитать онлайн книгу.
is perfectly true that, in certain circumstances, viruses do behave like inert chemicals. Indeed, I once performed a series of experiments that proved this. When I was a medical student at Sheffield University, I was interested in how our mammalian immune system would respond to viral invasion. The penetration of such alien organisms into our bloodstream – literally the very heart of our being – would be a major, and extremely threatening, event. With the help of my mentor, Mike McEntegart, Professor of Microbiology, I set up an experiment in which I injected viruses into the bloodstream of rabbits. Some readers might react with concern about hurting experimental animals, but the virus I used was a bacteriophage, known as ΦX174 – a virus that only attacks bacteria – so the rabbits suffered no illness. Yet their adaptive immune system responded in exactly the way it should to any alien invader, with a build-up of antibodies in two waves, rising to a peak by 21 days, where a single drop of their serum would be seen to inactivate a billion viruses in mere moments.
The point I am making is that this experiment, by its very design, did not really reproduce the living behaviour of viruses. Injecting a virus into such a host was the virological equivalent of landing people, unprotected, on the surface of Mars. The circumstances were unnatural to the virus and it could neither survive nor respond, in the behavioural sense, and so it died. Had I injected smallpox, or influenza, or HIV-1, into people, the result would have been altogether different. The virus would have come alive in its natural host and a fearsome interaction, virus-with-human, would have followed. As this suggests, it is a waste of time, from the definitional perspective, to consider viruses outside of their natural ecology. Outside the host, it could be argued that a virus really does behave much as Professor Wimmer’s formula – as an inert assemblage of genes and proteins. Only in the real circumstances of its life cycle, when it interacts with its natural host, do we witness the real nature of viruses.
This is why, like Terry Yates, I take the view that viruses, in their natural life cycles, should be regarded as life forms. In this sense the extreme reductionism of depicting a virus as a list of chemicals is implicitly absurd. We might similarly contrive a chemical formula for a human being, when we would end up listing a similar collection of atoms, albeit their numbers would be far more gargantuan. People who view viruses only as chemical assemblages miss the vitally important point that viruses have arrived on the scene through a vast, and exceedingly complex, trajectory of evolution, much as we have ourselves. And though Professor Wimmer might seem to be promoting the viewpoint of a virus as inert, this is not his thinking at all. His view of viruses is much the same as my own, and that of the majority of biologists. A virus may appear inert outside its host, but when it enters the host cell, he too regards it as coming alive. And what an extraordinary life form it turns out to be – for here, in the landscape of the host cell, it has the unique ability of taking over and driving the host genome to make it manufacture new viruses.
Here, in the cells of their natural hosts, viruses are born, like all other life forms. Moreover, they can die. When we treat viral illness with viricidal drugs, our purpose is to kill viruses, much as we use bactericidal drugs to kill bacteria. And, perhaps most important of all, the powerful forces of evolution apply to viruses, just as they do to all other life forms. That is why it is so difficult to cure people infected with viruses. If a virus was nothing more than an inert collection of chemicals, there would never have been an AIDS pandemic. The human immune system would have mopped them up from the circulation without any difficulty.
It is clearly important that we take the trouble to understand viruses. We all know that this is important to medicine in combating viral illness in people. It is important also to veterinary medicine in combating diseases in animals, as it is to agriculture in combating diseases in plants. But there is another, even more profound, reason why we should take the trouble to understand viruses. My subsequent researches, and those of virologists such as Luis Villarreal and Marilyn Roossinck, have made it increasingly evident that viruses have played a key role in the evolution of life, from its very beginnings on Earth to the magnificent diversity we see today. Nowhere has the contribution of viruses been more significant than in the evolution of the human species. Perhaps most amazingly of all, this creative role in human evolution and disease has been played by viruses with a very close resemblance to HIV-1.
I realise that these will appear to be startling claims. When I first proposed such novel concepts, they provoked a heady mixture of bafflement and denial. The reaction was hardly surprising since, if I was right, it appeared to threaten the hegemony of the so-called “synthesis theory”, the trilogy of principles that has stood fast for more than seventy years as the theoretical foundation of modern Darwinism.
What [The Double Helix] conveys … is how uncertain it can be, when a man is in the black cave of unknowing, groping for the counters of the rock and the slope of the floor, listening for the echo of his steps, brushing away false clues as insistent as cobwebs to recognise that something important is taking shape.
HORACE FREELAND JUDSON1
A key proposition that has been almost universally misinterpreted among non-scientists as the core of Darwin’s theory is the concept known as the “survival of the fittest”. Nothing could have more alienated religious sensibility, with its potential for misapplication to society, for example its misuse in condoning laissez-faire politics in relation to poverty and hunger, and worst of all its extrapolation to racial and ethnic abuse. It is important, therefore, to clarify the fact that Darwin did not invoke the term. On the contrary, the concept of survival of the fittest was the brainchild of the social philosopher Herbert Spencer, who first proposed it in his book, Principles of Biology, published in 1864.2 Spencer had been developing his own thread of thought even before he read Darwin’s Origin of Species, which was published some five years before his own Principles of Biology, but the social philosopher was not educated in biology, and, although his concept was widely seen as synonymous with, or even a clearer exposition of, what Darwin was supposed to have meant by his term “natural selection”, Spencer misunderstood Darwin’s scientifically grounded theory, and he misapplied it as an endorsement of his sociological philosophy. The scientific historians, and philosophers, who have examined Spencer’s ideas have concluded that he saw evolution as a purposeful progression of the physical world, including all biological organisms, the human mind, and human culture and society. Unfortunately it was Spencer’s sociological concept of survival of the fittest, as opposed to Darwin’s scientific concept of natural selection, that led to the inaptly named Social Darwinism of the early nineteenth century, with all of its unfortunate ramifications.
There was never any true scientific foundation to Spencer’s ideas, but since they conveniently fitted with some of the prevailing prejudices of class, and the ethnic and racial bias of the late nineteenth century, extending into the first half of the twentieth century, they became deeply ingrained and influenced political and social belief. It is tragic that Spencer’s ideas still influence a lot of non-scientists today, so that one frequently hears the expression “survival of the fittest” raised in defence or excuse of some prejudicial action. So ingrained did Spencer’s ideas become that, during his lifetime, Darwin himself was put under a lot of pressure, by Spencer and others, to change his basic premise, but, although he briefly flirted with Spencer’s idea, he quickly recovered his senses and returned to his original concept.
Why am I making such a fuss of this when it might be argued that a similar concept of “fitness” is central to Darwinian theory even today? Of course fitness is a core concept to evolutionary biology, but this Darwinian expression is far from the judgemental notion proposed by Spencer. What then did Darwin really imply with his theory of evolution by means of natural selection, and how does the Darwinian concept of “fitness” differ from Spencer’s notion of “the survival of the fittest”?
Admirers of David Attenborough’s Blue Planet series will have observed how, in the warmth of summer, the female Atlantic lobster, a species that can grow up to 20 kilograms in weight, decides that the