Gaia, << GAY uh or GY uh, >> is the idea that the earth is a living organism which functions as a unified whole to regulate conditions in the air, land, and water. Scientists call Gaia a hypothesis—that is, a possible explanation for what they have observed. It was named for Gaia, the ancient Greek goddess of the earth (also spelled Gaea or Ge).
Scientists have long known that living things alter the environment. Plants, for example, take up carbon dioxide from the air and give off oxygen. The Gaia hypothesis goes further, suggesting that life might actually keep the environment suitable for life. According to the theory, all living things—from the tiniest cells to the largest plants and animals—interact to create the environmental conditions that they need.
An example of how Gaia might work can be found in a tropical rain forest. Trees give off water through their leaves in a process called transpiration. By adding humidity to the air, the trees increase the number of rainstorms that occur. As a result, the environment necessary for a rain forest is maintained in two ways. First, the rain keeps the trees watered. Second, rain clouds block the sun to keep the forest from overheating.
The Gaia hypothesis was first presented in 1968 by James E. Lovelock, a British chemist, biologist, and inventor. He and American microbiologist Lynn Margulis have since refined the idea. The theory has aroused skepticism and controversy among scientists, some of whom consider aspects of it unscientific or unoriginal. Other experts think that research on Gaia may add to our understanding of serious environmental problems, such as the greenhouse effect and mass extinctions.
