The confluence of technology and imagination is what drives science forward, sometimes at astonishing speed. This has been especially true of biology since the structure of DNA was elucidated by Crick and Watson in 1953. The discovery of the chemical basis of life meant that it could be manipulated directly, by chemistry, rather than slowly and indirectly by selective breeding. But, of course, man came late to this game. Viruses had been attacking and subverting DNA for billions of years, and organisms have been defending themselves against such subversion for just as long. Slowly we have learned to find and appropriate the weapons of that long war and turn them to our own purposes. We now have access to tools of astonishing power and precision for the editing of DNA. At the same time we are able to manufacture the substance through pure chemistry. It’s possible to glimpse a future in which DNA engineering becomes something as relatively simple as software engineering, and its products become as easy to use.

Easy to use is not at all the same as safe. We have refined our nuclear engineering to the point where unimaginable destruction could be released at the press of a single button. Genetic engineering is not as spectacular, but it might have military applications almost as devastating – even if it were never used directly on humans. The results of a malevolent or a simply flawed experiment could devastate food supplies, weaken disease resistance or increase the virulence of existing pathogens. Entire ecosystems could be destroyed by thoughtless tinkering. This is not an entirely new threat. We have been doing that for millennia now: the history of the settlement of the Americas is (among other things) a ghastly chronicle of ecological destruction, the extermination of animal species, and the use of biological warfare against other human groups. So there is no reserve of natural goodness or moral luck which we can rely on to protect us against such dangers now that they are greater and closer than ever before in history. What will be needed is a profound sense of responsibility towards the planet and towards our fellow human beings.

None of this is an argument for trying to stuff the genie back into the bottle. Even if that were possible, which it is not, the new techniques of genetic engineering offer the prospect of great benefits if they are used responsibly. We didn’t hesitate to eradicate the smallpox virus in the wild using conventional methods. It’s hard to understand why we should not try to eliminate various disease-bearing species of mosquito with the new techniques, and the Gates foundation is seriously considering the feasibility of this. We already sift among embryos liable to terrible genetic flaws to ensure that only healthy ones are implanted in IVF procedure. If a technique were developed that enabled some of nature’s more ghastly mistakes to be corrected at a later stage, it would be hard to argue against its deployment. The great problem would come if the technology of synthetic DNA ever reached the point where we could specify the precise genome we wanted. That would make “designer babies” real in all the ways that present methods can’t. The urgent need then would be to improve human nature to give us the wisdom and the foresight we will need. Unfortunately, there is no prospect that these virtues could be implanted by gene-twiddling.