History 34 Video recordings for the hearing impaired 28 Global warming 27 Research 27 Climatic changes 26 Histology 26 Behavior 21 Mais ... Brain 20 Environmental aspects 20 Evolution (Biology) 18 Mathematics 17 Science 16 Effect of human beings on 14 Nature 14 Study and teaching 14 Cosmology 13 Evolution 12 Animals 11 Artificial intelligence 11 Ecology 11 Government policy 10 Cells 9 Congresses 9 Documentary television programs 9 Environmental protection 9 Greenhouse effect, Atmospheric 9 Human physiology 9 Human-animal relationships 9 Periodicals 9 Physicists 9 menos ...