CURIOUS: Genes that leap from one species to another are more common than we thought.

Most biologists viewed horizontal gene transfer among insects and other animals as something of an anomaly. Yes, bacteria and viruses exchanged DNA on a daily basis. But when it came to animals, plants and fungi, such genetic trespassing was surely rare overall and, in most cases, of little importance.

These are exactly the notions that have unravelled in the past decade as researchers have turned up one new case of gene transfer after another. ‘There was a time when we didn’t even realise that transposons could come from other species,’ says Cedric Feschotte of the University of Utah. ‘Now it seems our own genome is a patchwork of raw genetic material coming from different places with different histories – that to me is very profound. Even the largest eukaryote genomes have this patchwork origin to them.’