PUBLIC MARKS with tags life & evolution

In an advance toward understanding the origin of life on Earth, scientists have shown that parts of the Krebs cycle can run in reverse, producing biomolecules that could jump-start life with only sunlight and a mineral present in the primordial oceans. The Krebs cycle is a series of chemical reactions of central importance in cells — part of a metabolic pathway that changes carbohydrates, fats and proteins into carbon dioxide and water to generate energy.

Somewhere on Earth, close to 4 billion years ago, a set of molecular reactions flipped a switch and became life. Scientists try to imagine this animating event by simplifying the processes that characterize living things.