EVOLUTION 13 United States of America 13 SCIENCE 12 MICROBIAL LIFE 8 United States 8 INTERACTING SYSTEMS IN DEVELOPMENT 7 History 6 EVOLUTION: INTERNATIONAL JOURNAL OF ORGANIC EVOLUTION 5 Proceedings of the National Academy of Sciences (Journal) 5 America 4 CELL STRUCTURE AND FUNCTION 4 General history of North America - United States 4 Social Sciences 4 American Constitution-- USA and World War 3 BOTANY 3 GENETICS 3 Literature 3 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCE OF THE UNITED STATES OF AMERICA ( J ) 3 The LIVING PLANT 3 Women 3 Algebra 2 Arts 2 BIOLOGY 2 Bacteriology 2 Constitution of United States 2 Constitutional Law 2 Economics 2 English literature 2 Environmentalism 2 Geometry 2