Jake Buehler writes:

For well over 4 billion years, the fire of metabolism has powered the engines of life. The ability of cells to gather, transform, and harness chemical energy from their surroundings is the central force driving the dizzyingly complex network of chemical reactions that sustains living things.

Metabolism is so crucial to life that some researchers believe that these reactions could have helped spark life itself. They argue that life’s first glimmers were found in self-sustaining cycles of simple molecules, before genes or cells existed. Only later did more complex molecules like RNA and DNA develop and begin storing information for the purposes of heredity.

The core argument behind metabolism’s primacy is that without a self-sustaining reaction to provide energy, it’s impossible to explain how the larger and more complex molecules necessary for cellular life could have been produced at all. Energy going through the system is what life is in its many manifestations, said William Martin, an evolutionary biologist at Heinrich Heine University Düsseldorf in Germany. “It synthesizes genes that contain the information to produce the catalysts that keep this reaction going, and those catalysts have changed over time.”

The concept that reactions driven by nonliving geochemistry could have eventually triggered living biochemistry has been decades in the making. In 1968, the American biophysicist Harold Morowitz proposed that energy that flows through a system organizes that system, and he applied this to the concept of a proto-metabolism. Essentially, Morowitz suggested that energy from external environmental sources, such as the sun or geologic processes, could nudge chemical networks into self-sustaining reactions because they were thermodynamically favored. In time, those could become biological reactions. [Continue reading…]