Rocks May Have Given a Hand to Life

A long-standing mystery about the origin of life has a new possible solution.

A yellowish calcite crystal. Rob Lavinsky

The puzzle is that amino acids, the constituents of proteins, occur in two chemically identical forms that have structures mirroring each other like two gloves. Most chemical processes yield left- and right-handed amino acids in equal amounts yet life forms contain left-handed amino acids almost exclusively.