Overballe-Petersen proposes that the integration of these short fragments happens by a passive mechanism, one that pre-dates the process by which bacteria take up longer DNA fragments. Transformation usually ropes in the activity of around 40 different proteins, but when Overballe-Petersen's team knocked out RecA, a recombinase essential to the process, the bacteria still incorporated the short stretches of DNA. “It's a simple variant of the highly evolved, classical transformation,” he said.