Life arose on Earth almost as soon as the planet had cooled enough to be habitable – and as far as we know, it has never arisen again in the 4 billion years since. That long dry spell may end within the next few years, though, as researchers near the goal of making life from scratch in the lab.
Already, geneticists have synthesised a bespoke genome and inserted it into a bacterium. They have also altered the genetic code of other bacteria to get them to use new, non-natural building blocks to make proteins. But all these efforts start with a living organism and merely modify it.
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A more ambitious effort starts with nonliving, chemical ingredients – sometimes familiar nucleic acids and lipids, but sometimes radically different structures such as self-assembling metal oxides. The researchers aim to coax these chemicals across the Darwinian threshold where they begin to replicate themselves heritably and evolve – the key criteria for calling the system alive. If this can be achieved, the implications would be enormous.
Most fundamentally, synthetic life would complete the philosophical break – one that Darwin started – from a creation-centred view of the living world. “It’ll prove pretty decisively that life is nothing more than a complicated chemical system,” says Mark Bedau, a philosopher of science at Reed College in Portland, Oregon. Most scientists already think this way, of course, but synthetic life would make the point in a way the wider world could not ignore. Moreover, creating it in the lab would prove that the origin of life is a relatively low hurdle, increasing the odds that we might find life elsewhere in the solar system (see”The world in 2076: The population bomb has imploded“).
A second genesis would also give biologists an independent point of comparison to understand what makes life tick. And because we made it, we would be able to modify it, changing the ingredients to learn which features are truly essential.
The stuff we will end up calling “natural life” is so encumbered with billions of years of evolutionary baggage that it’s impossible to distinguish between what is truly essential for life and what has become essential for our particular sort, says Steven Benner from the Foundation for Applied Molecular Evolution in Florida. Newly created life would give experimentalists a cleaner system for testing life’s needs.
Practical payoffs are likely to be further in the future. Any new life form would be so feeble at first that it couldn’t survive without coddling in the lab, so biotechnologists who want to produce particular molecules or degrade toxic waste, for example, will have better success modifying natural life. In the long run, however, artificial life might grow robust enough to thrive on its own. If so, it would allow biotechnologists to escape the constraints of natural life to accomplish new goals. “We can explore all sorts of possible payoffs,” says Lee Cronin at the University of Glasgow, UK.
But those benefits bring risks, too. A free-living, independently evolving life form is, by definition, no longer entirely predictable or controllable. Biotechnologists will need to design effective “kill switches” in case the new life becomes pathogenic or harmful in other ways, and policy-makers and ethicists will need to work out when and how to trigger them. The public may try to stymie the whole enterprise, amid the usual accusations of playing God. Discussions on the implications of synthetic life need to start soon. “Within a short time, this could be a serious issue,” says Bedau.
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This article appeared in print under the headline “What if… We engineer new life forms?”
