 Yet the cycle did not come out of nowhere. It was cobbled together out of other cellular processes which do other things. It was a ‘bricolage’, that is to say it was something put together in a haphazard fashion. Each one of the bits and pieces of the cycle exists for other purposes and has been coopted for the new end. The scientists who have made this connection could not have made a stronger case against Behe’s irreducible complexity than if they had had him in mind from the first. In fact, they set up the problem virtually in Behe’s terms: ‘The Krebs cycle has been frequently quoted as a key problem in the evolution of living cells, hard to explain by Darwin’s natural selection: How could natural selection explain the building of a complicated structure in toto, when the intermediate stages have no obvious fitness functionality?’ (Meléndez-Hervia et al 1996, 302). (Readers who want to dig more deeply into some of the technical issues should start with the  entry on   fitness.)