Recreating the mix of compounds and experimental conditions that interacted over billions of years to create life on Earth is impossible in the lab. But an autonomous robot can shorten the time it takes to test each possible mixture, which could help reveal the precise combination that let proteins, DNA and enzymes emerge from the prebiotic soup on early Earth.
at the University of Glasgow, UK, and his colleagues built a robotic chemist that can mix simple molecules together, watch them react, analyse the result and then decide what to add to the reaction. Over several weeks, this robot can start to recreate a prebiotic soup scenario with almost no input from human chemists, he says.
鈥淲e wanted to remove the bias from the experiments and cover as much chemical space as possible to look for the spark of life,鈥� says Cronin.
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The set-up includes a tangle of tubes connecting 18 flasks of different starting materials to a central reaction vessel containing a range of clean, dry minerals such as quartz, ulexite and pyrite.
The starting materials are all small molecules with no biological or catalytic function, including simple acids, organics, reducing agents and some inorganic molecules like copper sulphate.
The robot chooses two or three of these reagents to suck into the reaction vessel, where the mixture is stirred and heated for an hour, then allowed to settle. It analyses the sample, and a portion is taken away for storage and human analysis later. A small amount of the brew is left as a seed mixture, and the robot then adds a fresh batch of reagents, and the process repeats. The team ran the robot for up to 150 of these cycles over many days.
The robot鈥檚 decisions on whether to let a reaction continue or to introduce a molecule into the brew are based on readings from a mass spectrometer, which reveals the size of the different molecules within the mixture.
If these readings suggest no change has happened in the mixture, the robot will work to push the system back away from a state of equilibrium by adding something new in the next cycle. 鈥淚t鈥檚 an anti-boredom algorithm,鈥� says Cronin.
The robotic chemist doesn鈥檛 allow us to work out how life formed yet, but it is a useful tool to let us step towards it 鈥� and a vast improvement on the effort one person at the bench could make, says at the University of Groningen in the Netherlands.
鈥淭he problem with chemical space is it鈥檚 more than astronomical [space], so you cannot possibly cover it at all,鈥� says Otto. But with the right mix of starting materials that might not be a problem. 鈥淭he hope with these experiments is that something autocatalytic emerges from it,鈥� he says, meaning when a reaction produces its own catalyst in the process. Autocatalytic reactions are considered essential for life to emerge.
at the Czech Academy of Sciences says that in origin-of-life experiments, humans tend to get in the way. But Cronin鈥檚 work significantly reduces human bias, she says.
Cronin is encouraged by what has happened so far. 鈥淲e鈥檝e seen tentative evidence of molecular replication,鈥� he says. Complex molecules are forming, and despite being diluted away at the start of each new cycle, those molecules persist, he says.
Cronin is planning a bigger version of the robot. 鈥淭his is a dummy run,鈥� he says. With more complex algorithms, the team will hope to see evidence of large, complex molecules that can process information.
Nature Communications
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