Sean Carroll in Preposterous Universe:
The origin of life here on Earth was an important and fascinating event, but it was also a long time ago and hasn’t left many pieces of direct evidence concerning what actually happened. One set of clues we have comes from processes in current living organisms, especially those processes that seem extremely common. The Krebs cycle, the sequence of reactions that functions as a pathway for energy distribution in aerobic organisms, is such an example. I talk with biochemist about the importance of the Krebs cycle to contemporary biology, as well as its possible significance in understanding the origin of life.