Environmental aspects Environmental conditions Social conditions Ecology 17 History 16 Social aspects 16 Environmentalism 9 more ... Effect of human beings on 8 Nature 8 Urbanization 7 Human ecology 6 Urban ecology (Sociology) 6 City planning 5 Economic conditions 5 Political aspects 4 Race relations 4 African Americans 3 Economic aspects 3 Economic history 3 Environmental justice 3 Ethnic relations 3 Ethnology 3 Forests and forestry 3 Gold mines and mining 3 Landscapes 3 Political activity 3 Politics and government 3 Pollution 3 Social change 3 Black Death 2 less ...