Some three billion years ago, when life on this planet was still in its infancy, hot springs, geysers and volcanic hydrothermal vents were burgeoning with single-cell organisms. Temperatures hovered around a burning hot 180 degrees. In a few hundred million years, the basic elements of our genetic code and cellular machinery all came into being.
Then it started to get colder. Standing on the equator 1 billion years ago, it would have been as cold as today's Antarctic.
Of course this story has a happy ending — life developed anyway — but how it managed to adapt to the earth’s cooling remains something of a mystery. Now, in the cover story of the January 20 issue of Science, Professor of Biochemistry Dorothee Kern offers an explanation as to how enzymes — key catalysts in cells — braved the cold. "It's one more clue to how life evolved on this planet," she says.