A tiny creature illuminates an important biological advance

THE ROADTV to human beings was long and winding. But a big step on it was the first eukaryotic cell. Eukaryotes comprise the living world as it is familiar from documentaries: animals (humans included) and also plants, seaweeds, fungi and a host of other types of creature too tiny for the naked eye, but which flit around attractively under a microscope.This extraordinary diversity was made possible because, unlike the cells of life’s other two great realms, the bacteria and the archaea, eukaryotic cells have lots of internal structures known as organelles. The division of labour which these organelles permit has allowed eukaryotes not merely to evolve, but to become gradually more sophisticated over the ages in ways that bacteria and archaea have never managed. How organelles came into existence is therefore a matter of great biological interest. And a discovery made recently in the depths of Lake Zug, in Switzerland, has cast a bit more light on the subject.