2019年4月6日刊社论

Redesigning life

重新设计生命

The promise and perils of synthetic biology

合成生物学的发展前景及风险

For the past four billion years or so the only way for life on Earth to produce a sequence of DNA—a gene—was by copying a sequence it already had to hand. Sometimes the gene would be damaged or scrambled, the copying imperfect or undertaken repeatedly. From that raw material arose the glories of natural selection. But beneath it all, gene begat gene.

在过去40亿年左右的时间里，地球上生命产生DNA序列——基因——的唯一方法就是复制它已有的序列。有时基因会受到破坏或者发生混乱，导致复制存在缺陷或重复进行，而这也为多彩的自然选择提供了原材料。但万变不离其宗，基因孕育了基因。

That is no longer true. Now genes can be written from scratch and edited repeatedly, like text in a word processor. The ability to engineer living things which this provides represents a fundamental change in the way humans interact with the planet’s life. It permits the manufacture of all manner of things which used to be hard, even impossible, to make: pharmaceuticals, fuels, fabrics, foods and fragrances can all be built molecule by molecule. What cells do and what they can become is engineerable, too. Immune cells can be told to follow doctors’ orders; stem cells better coaxed to turn into new tissues; fertilised eggs programmed to grow into creatures quite unlike their parents.

事实已非如此。现如今，人们可以像在文字处理器中处理文本一样，从无到有地编写基因，并对其进行反复编辑。由此而来的这种设计生物的能力代表了人类与地球生命互动方式的根本改变。它使得制造各种各样过去很难甚至不可能制造的东西成为可能：药品、燃料、织物、食品和香水都可以逐个分子地制造出来。细胞会干什么，它们能成为什么样的细胞，也都是可以设计的。免疫细胞可以按要求听从医生的指令；干细胞可以通过更好的诱导转化成新的组织；受精卵可以借助编程发育成完全不同于父母的人。

The earliest stages of such “synthetic biology” are already changing many industrial processes, transforming medicine and beginning to reach into the consumer world. Progress may be slow, but with the help of new tools and a big dollop of machine  learning, biological manufacturing could eventually yield truly cornucopian technologies. Buildings may be grown from synthetic wood or coral. Mammoths produced from engineered elephant cells may yet stride across Siberia.

这类尚处于最初阶段的“合成生物学”已经在改变很多工业生产过程，让医药焕然一新，并开始进入消费领域。进展也许还比较缓慢，但借助于新工具和大量的机器学习，生物制造技术终能硕果累累。用合成木材或珊瑚建造的楼宇也许会拔地而起，而通过大象细胞基因编辑产生的猛犸象可能会跨越西伯利亚。

The scale of the potential changes seems hard to imagine. But look back through history, and humanity’s relations with the living world have seen three great transformations: the exploitation of fossil fuels, the globalisation of the world’s ecosystems after the European conquest of the Americas, and the domestication of crops and animals at the dawn of agriculture. All brought prosperity and progress, but with damaging side-effects. Synthetic biology promises similar transformation. To harness the promise and minimise the peril, it pays to learn the lessons of the past.

可能发生的变化之大，似乎难以想象。但是回顾历史，人类与生物世界的关系经历了三次巨大的转变：化石燃料的开采、欧洲征服美洲后世界生态系统的全球化，以及农业发展初期农作物的培植和动物的驯化。所有这些都带来了繁荣和进步，但也产生了破坏性的副作用。合成生物学可能也会造成类似的转变。为了利用好发展前景同时将风险降至最低，吸取过去的教训，何乐而不为呢！

The new biology calls all in doubt

新的生物学让一切都充满了疑问

Start with the most recent of these previous shifts. Fossil fuels have enabled humans to drive remarkable economic expansion in the present using biological productivity from ages past, stored away in coal and oil. But much wilderness has been lost, and carbon atoms which last saw the atmosphere hundreds of millions of years ago have strengthened the planet’s greenhouse effect to a degree that may prove catastrophic. Here, synthetic biology can do good. It is already being used to replace some products made from petrochemicals; in time it could replace some fuels, too. This week Burger King introduced into some of its restaurants a beefless Whopper that gets its meatiness from an engineered plant protein; such innovations could greatly ease a shift to less environmentally taxing diets. They could also be used to do more with less. Plants and their soil microbes could produce their own fertilisers and pesticides, ruminants less greenhouse gas—though to ensure that synthetic biology yields such laudable environmental goals will take public policy as well as the cues of the market.

先说说最近发生的这些转变。化石燃料让人类能够利用过去储存在煤和石油中的生物生产力，推动当今显著的经济扩张。但是很多荒野消失了，几亿年前最后一次出现在大气中的碳原子也让地球的温室效应增强了，其程度可能被证明是灾难性的。在这方面，合成生物学可以发挥作用。它已经被用来取代一些石油化工产品；假以时日，它也会替代一些燃料。本周，汉堡王(Burger King)在其部分餐厅推出了一款无肉皇堡，其肉质口味来自一种基因工程植物蛋白；这类创新可以极大地方便向低环境负担饮食的转变。有了这些创新，可以少花钱多办事。植物及其土壤微生物可以生产自己的化肥和杀虫剂，反刍动物可以排出更少的温室气体——不过，为了确保合成生物学能够达成如此值得称赞的环境目标，既要考虑公共政策，也需要市场引导。

The second example of biological change sweeping the world is the Columbian exchange, in which the 16th century’s newly global network of trade shuffled together the creatures of the New World and the Old. Horses, cattle and cotton were introduced to the Americas; maize, potatoes, chilli and tobacco to Europe, Africa and Asia. The ecosystems in which humans live became globalised as never before, providing more productive agriculture all round, richer diets for many. But there were also disastrous consequences. Measles, smallpox and other pathogens ran through the New World like a forest fire, claiming tens of millions of lives. The Europeans weaponised this catastrophe, conquering lands depleted and disordered by disease.

生物变化席卷世界的第二个例子是哥伦布交换，16世纪新形成的全球贸易网络将新世界与旧世界的生物混杂在一起。马、牛和棉花被引入美洲；玉米、土豆、辣椒和烟草被销往欧洲、非洲和亚洲。人类赖以生存的生态系统前所未有地全球化，提高了各地农业生产力，为许多人带来更丰富的饮食。但也有灾难性的后果。麻疹、天花和其他病原体像森林大火一样在新世界蔓延，夺走了数千万人的生命。欧洲人拿这场灾难当作武器，征服了因疾病而枯竭和混乱的土地。

Synthetic biology could create such weapons by design: pathogens designed to weaken, to incapacitate or to kill, and perhaps also to limit themselves to particular types of target. There is real cause for concern here—but not for immediate alarm. For such weaponisation would, like the rest of cutting-edge synthetic biology, take highly skilled teams with significant resources. And armies already have lots of ways to flatten cities and kill people in large numbers. When it comes to mass destruction, a disease is a poor substitute for a nuke. What’s more, today’s synthetic-biology community lives up to ideals of openness and public service better than many older fields. Maintained and nurtured, that culture should serve as a powerful immune system against rogue elements.

合成生物学可以通过设计制造出这样的武器：设计具有削弱、致残或杀伤性的病原体，或许还可以针对特定类型的目标设计相应的病原体。这确实令人感到担忧，但眼下我们不必紧张。这是因为，这类武器化设计将像其他尖端合成生物学一样，需要拥有巨大资源的高技术团队。而且，军队已经有很多办法去大规模地夷平城市，杀戮民众。就大规模杀伤性而言，疾病并不能很好地替代核武器。更为重要的是，相比诸多古老的研究领域，现今的合成生物学界更加开放透明，也更加秉承服务大众的理念。这种文化如果得以传承和发扬，应该能够像一个强大的免疫系统一样，抵御胡作非为之徒。

The earliest biological transformation—domestication—produced what was hitherto the biggest change in how humans lived their lives. Haphazardly, then purposefully, humans bred cereals to be more bountiful, livestock to be more docile, dogs more obedient and cats more companionable (the last a partial success, at best). This allowed new densities of settlement and new forms of social organisation: the market, the city, the state. Humans domesticated themselves as well as their crops and animals, creating space for the drudgery of subsistence agriculture and oppressive political hierarchies.

最早的生物学转变——驯养——使人类生活方式发生了迄今为止最大的变化。通过人类先是随意而后又有目的地培育和驯养，谷物更加丰裕，牲畜更加温顺，狗更加听话，猫更加友善（最后一种情况充其量只能算是部分成功）。新的密集定居地和社会组织形式由此形成：市场、城市和国家。人类不仅驯养了农作物和动物，也教化了自己，繁重而乏味的自给性农业和压迫性政治等级制度因此得以存续下来。

Synthetic biology will have a similar cascading effect, transforming humans’ relationships with each other and, potentially, their own biological nature. The ability to reprogram the embryo is, rightly, the site of most of today’s ethical concerns. In future, they may extend further; what should one make of people with the upper-body strength of gorillas, or minds impervious to sorrow? How humans may choose to change themselves biologically is hard to say; that some choices will be controversial is not.

合成生物学将产生类似的连锁效应，不仅改变人类彼此之间的关系，并可能改变人类自身的生物特性。对胚胎进行重新编程的能力成为当今大多数伦理问题的焦点，这是理所当然的事情。在未来，它们可能会进一步延伸拓展；我们应该如何看待拥有大猩猩上半身力量的人，或者不会产生悲伤情绪的人？人类如何选择从生物学上改变自己还很难说；而其中有些选择将会引起争议，却是明摆着的。

Which leads to the main way in which this transformation differs from the three that came before. Their significance was discovered only in retrospect. This time, there will be foresight. It will not be perfect: there will certainly be unanticipated effects. But synthetic biology will be driven by the pursuit of goals, both anticipated and desired. It will challenge the human capacity for wisdom and foresight. It might defeat it. But carefully nurtured, it might also help expand it.

这一次转变的主要方式与之前的三次是不同的，为何？之前的几次转变，人们只是在回顾历史时才发现其重要意义。而这一次，人们将有远见卓识。它不会是完美的：肯定会产生意想不到的影响。但是，推动合成生物学向前发展的，将是人们对预料之中或者渴望实现的目标的追求。它将挑战人类的智慧和远见——也许会战胜人类的智慧和远见，但如果加以精心培育扶持，它也可能会让人类变得更有智慧、更有远见。

（陈继龙译自《经济学人》杂志2019年4月6日刊）