Soviet biologist Georgii Frantsevich Gause (1910--86) was based at the Zoological Institute of the University of Moscow and devoted a large part of his working life to the study of antibiotics. He formulated the competitive exclusion principle, a fundamental law of ecology, based on his research with yeast cultures and Paramecium species. The principle states that when two species compete for the same requirements, one will always be slightly more efficient than the other and will reproduce at a higher rate, and the less efficient species will face local extinction.