Chirality in biology has puzzled chemists for decades. Why is it that life mainly uses just one chiral form of amino acids and other biomolecules? A new clue offers a potentially crystal clear answer as scientists at the National Central University in Taiwan, have identified a crystal that may have first stimulated the chiral bias in biology billions of years ago. Tu Lee and Yu Kun Lin point out that conditions on the primordial Earth held an equal chance of forming the same amounts of left-handed and right-handed amino acids. They have demonstrated that left-handed aspartic acid crystals predominate in reaction conditions similar to those that might have existed at the dawn of life through preferential crystallization.