Benefits of nature: what we are learning about why people respond to nature.

People have positive aesthetic, emotional, and physiological responses to nature. Why is this so? The "savanna hypothesis," proposed by Gordon Orians, predicts that some human responses are based on innate knowledge of productive human habitats. To test this, researchers have examined particular aspects of nature that should be associated with productive human habitats to see if they trigger positive responses in people. Tree form has emerged as an important factor in these studies. People prefer looking at trees with spreading forms much more than looking at trees with other forms. Trees with spreading forms existed on the African savanna and were associated with habitats that were good for early human habitation. We have shown that subjects also feel happier when looking at these trees than when looking at other trees or non-tree objects. Color is another variable that might be associated with people's responses to nature. Bright green colors could be an important cue for healthy plants with good nutrient qualities. We measured subjects' physiological responses to tree canopies of various colors and found that all colors were calming, but bright green trees were more calming than other tree colors, including less bright greens and oranges. Adult responses to plants are also influenced by their childhood interactions with nature. We have shown that the more interaction people have with nature as children, the more positive are their attitudes towards nature as adults. These positive responses have been documented in people from a wide range of backgrounds.