How do bacteria survive encased in ice for millions of years? Scientist used to believe the genetic material was essentially frozen in stasis. New studies suggest that in order to stay viable the bacteria must undergo continual DNA repair over the many long years of preservation. PNAS. If life is to be found on Mars or Europa, they suggest, the best place to look will be in ice.
In the Dry Valleys of the Transantarctic Mountains there are pockets of ice up to 8 million years old. Last week, scientists announced that they resuscitated microbes from this ice. If the microbes are as old as the ice, they were around long before humans split from the chimpanzee/bonobo line, approximately 6 million years ago. The scientists call their sample a "gene popsicle" and speculate that in periods of the Earth's history when ancient ice melted, microbes in samples like theirs might have been reincorporated into current populations--which might be something like dating your great- great- great- to-the-1000th grandmother. They also wonder if the preservation of microbes in icy comets may have seeded planets with genetic material as distant in space as well as time. PNAS, National Geographic.