In my last reading of A Contract with the Earth, Newt Gingrich and Terry Maple quote a statement by Richard Louv in Last Child in the Woods:
"Nature----the sublime, the harsh, and the beautiful----offers something that the street or gated community or computer game cannot. Nature presents the young with something so much greater than they are; it offers an environment where they can easily contemplate infinity and eternity."
Louv's point (in the words of Newt and Maple) is that "children need exposure to nature for the healthy development of their senses, to learn and to create" (page 181). Louv believes that their lack of exposure to nature has contributed to ADHD. Earlier in the book, on page 176, Newt and Maple refer to the example of Charles Darwin, who was enchanted with nature from an early age and whose "youthful enthusiasm for nature lasted a lifetime" (page 176). (Is Newt a Republican who believes in evolution?)
I believe that nature is valuable apart from whether or not it benefits human beings, but I do agree with Newt and Maple that people lose out when they are not exposed to nature. Nature makes us feel small when we look at its greatness and beauty. It inspires us and makes us think about "infinity and eternity".