One of the goals of nanotechnology is to mass-produce tiny building blocks that might be assembled into tiny machines. A few years ago, Gerald Joyce and his friends at the Scripps Research Institute in California published a paper in Nature announcing the first mass production of such building blocks. They showed pictures of building blocks in the shape of regular octahedra, identical in size and structure, each of them perfectly rigid with a diameter of twenty-two nanometers. They look as if they were solid objects shaped and sliced by a mechanical tool. But in fact they are nothing of the kind. They are made of pure DNA and are synthesized by the polymerase chain reaction. The technology that produced them is pure biotechnology and has nothing to do with machine tools. Joyce and his friends designed a DNA molecule so it would fold spontaneously into the octahedral shape as a result of bonding of complementary DNA bases. They mass-produced it by inserting the DNA into the genome of E. coli bacteria and letting the bacteria multiply. With a little help from E. coli, a group of biologists beat the nanotechnologists at their own game.
What would it take to construct the self-replicating assembler that Eric Drexler proclaimed as the holy grail of nanotechnology twenty-five years ago? The mathematician John von Neumann answered this question definitively in 1948 in his classic study of mechanical automata. He proved by logical analysis that any self-replicating automaton must have four components: Component A is an automatic factory. Component B is a copying machine. Component C is a control machine to control the actions of A and B. Component D is a blueprint containing a complete description of A and B and C. Five years later, Crick and Watson discovered the double helix, and it became clear that every living cell possesses these four components. A is the ribosomes, B is the polymerase enzymes, C is the enzymes controlling cell division, D is the genome composed of DNA or RNA. Now suppose that the nanotechnologists are trying to construct a self-replicating assembler. They will have to construct these four components and arrange them in to function together as they do in a living cell. In the end they will have only reinvented something like a bacterium. Biotechnology can do the same job more reliably and much more cheaply. This being so, the menace of grey goo loses credibility. If the self-replicating assembler is made of truly nonbiological materials, it will not be able to replicate itself by eating existing forms of life. If it is made of biological materials, then it is only another kind of biological disease germ. Either way, the nightmare of the assembler becoming a grey goo and eating up the biosphere cannot happen. It may be very nasty but it is not going to wipe us out. I conclude that the dangers of nanotechnology, like its achievements, have been oversold. The dangers, if it succeeds in achieving its goals, will be essentially the same as the dangers of biotechnology.
Second, I spoke about the biologists who have worried about the dangers of biotechnology for at least forty years and have successfully taken political action to keep disasters from happening. I spoke to Matthew Meselson and Joshua Lederberg, leaders in the fight against biological weapons, and Maxine Singer and Paul Berg, leaders in the fight for international regulation of gene-splicing experiments. As a result of their efforts, the international community of biologists, and to some extent the international community of political leaders, are aware of the magnitude of the dangers and of the need for further action as the technology moves ahead. Nobody denies that biological weapons are an enormous threat, and that the threat comes as much from freelance terrorist groups as from national governments. But the biologists have been far more wholehearted and effective in fighting against biological weapons than physicists have been in fighting against nuclear weapons. Concerned citizens like Bill Joy have a lot to learn from the biologists.
Third, I spoke about the history of biological weapons and gene-splicing experiments, and the successes and failures of efforts to regulate them. Gene-splicing experiments began in many countries when the technique of sticking pairs of DNA together was discovered in 1975. Maxine Sanger and Paul Berg issued a call for a moratorium on all such experiments until the dangers could be carefully assessed. There were obvious dangers to public health if genes for deadly toxins could be inserted into bacteria that are normally found in human populations. Biologists all over the world immediately agreed to the moratorium, and experiments were halted everywhere for ten months. During the ten months, two international conferences were held to work out the guidelines for permissible and forbidden experiments. The guidelines established rules of physical and biological containment for permitted experiments involving various degrees of risk. The most dangerous experiments were forbidden outright. These guidelines were adopted voluntarily by biologists and have been observed ever since, with some changes from time to time in response to new discoveries. As a result, no serious risks have arisen from the experiments in twenty-five years. This is a shining example of responsible citizenship, showing that it is possible for scientists to protect the public from injury while preserving the freedom of science.
The history of biological weapons is a more complicated story. The United States, Great Britain, and the Soviet Union all had large programs to develop and stockpile biological weapons during and after the Second World War. But these were low-key efforts compared to the programs to develop nuclear weapons. Unlike the leading physicists who pushed the nuclear bomb programs ahead with great enthusiasm, the leading biologists never pushed hard for biological weapons. The great majority of biologists had nothing to do with weapons. The few leading biologists who were involved with the weapons program were mostly opposed to it. The strongest of the opponents in the United States was Matthew Meselson, who had the good luck to be a neighbor and friend of Henry Kissinger in 1968 when Nixon became president. Kissinger became national security advisor to President Nixon. Meselson seized the opportunity to convince Kissinger, and Kissinger convinced Nixon, that the American biological weapons program was far more dangerous to the United States than to any possible enemy. On the one hand, it was difficult to imagine any circumstances in which the United States would wish to use those weapons, and on the other hand, it was easy to imagine circumstances in which some of the weapons would fall into the hands of a group of terrorists. So Nixon in 1969 boldly declared that the United States was dismantling the entire program and destroying the stockpile of weapons. This was a unilateral move, not requiring any international agreement or ratification by the American Senate. The development of weapons was duly stopped, and the weapons were destroyed. Britain quickly followed suit. In 1972, as a result of Nixon's initiative, and international convention was signed by the United Stated, the United Kingdom, and the Soviet Union imposing a permanent prohibition of biological weapons on all three countries. Many other countries subsequently signed the convention.
As we now know, the Soviet Union violated the biological weapons convention of 1972 on a massive scale, continuing to develop new weapons and to accumulate stockpiles until the collapse of the USSR in 1991. After the collapse, Russia declared its adherence to the convention and announced that the Soviet program had now finally been stopped. But many of the old soviet research and production centers remain hidden behind walls of secrecy, and Russia has never provided the world with convincing evidence that the program is not continuing. It is quite possible that stockpiles of biological weapons continue to exist in Russia and in other countries. Nevertheless, the 1972 convention remains legally in force, and the great majority of countries have signed it. Although the convention is unverifiable and although it has been violated, we are far better off with it than without it. Without the convention, we would not have any legal ground for complaint or for preventative action whenever a biological weapons program is discovered. With the convention, the danger of biological weapons is not eliminated but it is significantly reduced. Again, biologists in general and Matthew Meselson in particular deserve credit for making this happen in the real world of national politics and international rivalries.
The fourth and last part of my reply to Bill Joy concerns the question of remedies for the dangers that we all agree exist. Bill says, "Internationalize control of knowledge," and "Relinquish pursuit of that knowledge so dangerous that we judge it better that (it) never be available." He is advocating censorship of scientific inquiry, either by international or by national authorities. I am opposed to this kind of censorship, and I will now explain why. From this point on, my argument in the Davos debate followed the same script that I had used when I testified on a previous occasion to the U.S. Congress.
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