How evolution builds genes from scratch

In the past five years, researchers have found numerous signs of newly minted ‘de novo’ genes in every lineage they have surveyed. De novo genes are even prompting a rethink of some portions of evolutionary theory. Conventional wisdom was that new genes tended to arise when existing ones are accidentally duplicated, blended with others or broken up, but some researchers now think that de novo genes could be quite common: some studies suggest at least one-tenth of genes could be made in this way; others estimate that more genes could emerge de novo than from gene duplication. Their existence blurs the boundaries of what constitutes a gene, revealing that the starting material for some new genes is non-coding DNA (see ‘Birth of a gene’).