Natural history History 424 Description and travel 384 Ecology 118 Science 118 Naturalists 110 Pre-Linnean works 99 Máis ... Travel 97 Environmental conditions 93 Nature 82 Animals 81 Nature in literature 79 Social life and customs 68 Human ecology 65 Indians of North America 60 Knowledge 57 Discovery and exploration 53 History and criticism 51 Biology 48 Geology 48 Zoology 47 Mollusks 46 Philosophy 42 Effect of human beings on 41 Evolution (Biology) 37 Homes and haunts 37 Antiquities 34 Physical geography 34 Scientific expeditions 34 Study and teaching 33 menos ...