Water gave life on Earth a guiding hand.

The article focuses on a study conducted by Uwe Meierhenrich at the University of Nice-Sophia Antipolis in France, which suggested last year that circularly polarised radiation may have preferentially destroyed right-handed amino acids arriving from space, leaving behind L-amino acids to form the building blocks of life. Now Meir Shinitzky at the Weizmann Institute of Science in Rehovot, Israel, has suggested the answer may lie here on Earth. While most fundamental physical forces act identically on left-handed and right-handed versions of particles, there is one force that does not. His team has been looking for this difference in polyglutamic acid (PGA), an orderly spiral chain made up of 24 glutamic acid units. While conventional thinking predicts that solutions of L-PGA and D-PGA ought to unwind in exactly the same way, Shinitzky found that twice as much hydrochloric acid is needed to break down the L-PGA spiral as is required for its counterpart.