Explosive twist (Image: Robert Mallozz/Marshall Space Flight Center)
MR SPOCK is dying. Fortunately for the crew of the USS Enterprise, the Spock in question is not the real one, but an evil mirror-image version created in a freak transporter malfunction. This Spock’s back-to-front body can digest only right-handed amino acids; meanwhile, like all organic matter, the food around him is made of left-handed amino acids. He is starving in the midst of plenty.
This plot line from the 1970 novel – the first literary spin-off from the Star Trek TV series – highlights one of life’s fundamental mysteries. Why does biology use only one of two mirror-image forms in which most complex molecules can occur? The latest pop at an answer weaves astrophysics, particle physics and biochemistry into a startling proposal: that the stellar explosions known as supernovae are to blame.
“It is an intriguing idea,” says , an astrobiologist at the NASA Goddard Flight Center in Greenbelt, Maryland. It is certainly a novel turn in this twistiest of tales: the story of how life came to be left-handed.
The property of handedness, known to chemists as , is a feature of many molecules whose arrangement of atoms is not completely symmetrical. A chiral molecule comes in two forms that are rather like a pair of gloves. Right and left-handed gloves are essentially identical, with the same basic components, four fingers and a thumb, and the same function of keeping our hands snug and protected. They are not exactly the same, however: you cannot rotate or flip a glove of one type so that it will superimpose…
