Evidence of life on Mars, even if only in the distant past, would finally answer the age-old question of whether living beings on Earth are alone in the universe. The magnitude of such a discovery is illustrated by President Bill Clinton’s appearance at a 1996 press conference to announce that proof had been found at last. A meteorite chipped from the surface of the Red Planet some 15 million years ago appeared to contain the fossil remains of tiny life-forms that indicated life had once existed on Mars.
Geologic research showing that similar creatures, smaller than any beings previously encountered or even imagined, could have shaped Earth’s early terrain suggested these specimens might be relics from the very dawn of life. The only news that could top such findings would come next: evidence that those ancient entities, which would come to be known as nanobacteria, were still among us—indeed, dwelling in our own bodies and potentially causing a range of illnesses.