Human beings Effect of environment on 53 Human ecology 26 Nature 22 Effect of climate on 21 Effect of human beings on 19 Climatic changes 17 Social aspects 16 History 12 Human evolution 12 Origin 10 Human engineering 8 Migrations 7 Global environmental change 6 Fossil hominids 5 Labor productivity 5 Social evolution 5 Work environment 5 Economic aspects 4 Environmental aspects 4 Environmental policy 4 Mathematical models 4 Paleoanthropology 4 Philosophy 4 Case studies 3 Disaster relief 3 Emigration and immigration 3 Environmental sciences 3 God 3 Human geography 3