Out of all the possible molecules in the world, just two form the basis of life’s grand variety: DNA and RNA. They alone can store and pass on genetic information. Within their repetitive twists, these polymers encode the stuff of every whale, ant, flower, tree and bacterium.

But even though DNA and RNA play these roles exclusively, they’re not the only molecules that can. Vitor Pinheiro from the MRC Laboratory of Molecular Biology has developed six alternative polymers called XNAs that can also store genetic information and evolve through natural selection. None of them are found in nature. They are part of a dawning era of “synthetic genetics”, which expands the chemistry of life in new uncharted directions.

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DNA looks like a