Opponents of evolution often complain that it is not seen in real time – but now that objection is gone. Zachary Blount of Michigan State University and colleagues grew E. coli bacteria for almost 25 years and followed them for more than 56,000 generations starting in 1988. The idea was to see if some of them would evolve to consume citrate as a nutrient. While E. coli may have been able to do this long ago, the ability to consume citrate in the presence of oxygen was lost at least 13 million years ago.

Around 33,000 generations into the experiment, one strain learnt the trick. It took three steps, taking place over more than 13,000 generations, to develop this ability. This experiment demonstrates that evolution really does take place and it even reveals how pre-existing genetic information is reshuffled to give rise to new characteristics. Darwin would have been thrilled.