Many of life's building blocks, such as amino acids, sugars and other molecules, are chiral -- meaning they come in two identical forms, mirror images of each other. Most life on Earth tends to prefer one side over the other, such as right-handed glucose molecules. But some forms of bacteria are less choosy.
Most life is left-handed, but its lower forms are ambidextrous, according to a new study reported in New Scientist. This might complicate the search for life on other planets, but it could also explain the Viking Mars landers' odd findings four decades ago.