Gaia hypothesis
The Gaia hypothesis posits that living systems interact with physical components of the Earth system to form a self-regulating whole that maintains conditions that are favourable for life. Developed initially by James Lovelock, the hypothesis attempts to account for key features of the Earth system, including the long period (several billion years) of relatively favourable climatic conditions against a backdrop of steadily increasing solar radiation. Consequently, the Gaia hypothesis has important implications for Earth system science, as noted by NASA's Director for Planetary Science, James Green, in October 2010: "Dr. Lovelock and Dr. Margulis played a key role in the origins of what we now know as Earth system science".