How can humanity manage someday to support more than 9 billion lives on one small planet -- an island floating in an ocean of space -- without destroying the environment? Can our energy systems operate solely on renewable energy and still be affordable? Can we truly feed ourselves from local agriculture and maintain the diets of developed countries?
The more we do to sanitize our environment of all pathogens, while also accepting the rampant use of complex agricultural chemicals to control so-called "pests," the less able we are to fend off disease of all kinds in more natural ways, which then increases our own dependence on modern pharmaceuticals to keep from being sick.
Jennifer is one of five teenagers spending her summer days at Philadelphia's Lutheran Settlement House as part of the Teens 4 Good program. Every morning, she arrives ready to work the patch of green in the heart of the city. But every night, she returns to the homeless shelter for women where she's living now.