By Lena VOROBYEVA, Dr. Sc. (Biol.), M.V. Lomonosov Moscow State University A most significant event in 20th-century biology occurred twenty-six years ago as a new form of life was discovered. These are Archaeota, the organisms remarkable for a peculiar, hitherto unknown mode of existence. Side by side with the domains of eukaryotes and prokaryotes, they constitute what we might call a third domain of life... Ancient philosophers pointed to the dichotomy (dual, twofold nature) of the living world composed that it was of the plant and animal kingdoms. With the discovery of microorganisms by the Dutch natural scientist Antony van Leewenhoek in 1683 (which he called "little animals") the animal kingdom came to be divided into two essential parts- the micro- and the macro-organisms. And with the appearance of electron microscopy in the 1950s microbiologists, who could now study cell structures, divided all organisms into eukaryotes (with a discrete cell nucleus) and prokaryotes (having no cell nucleus). Accordingly, two types of ribosomes, eukaryotic and prokaryotic, were thought to correspond to these two levels of cell organization. But one had no inkling of two distinct forms of prokaryotic life! The discovery of a new domain of life by a research team of Illinois University under Carl Woese in 1977 opened a new page in biology. This event is compared to the discovery of Australia (in 1606), a continent heretofore unknown to Europeans who were stupefied to see the kangaroo and eucalyptus trees for the first time there. Archaeota hold a key to our understanding of the origins of primitive life, of the eukaryotic cell in particular. They enable a better insight into the evolution of metabolism, photosynthesis and information processes. The development of our planet is closely related to the existence of prokaryotes-in fact, the microbes account for more than 90 percent of the philogenetic*, metabolic, molecular and ecological diversity of the earth. The discovery of ... Read more