The Gaia hypothesis holds that living organisms and their inorganic surroundings (atmosphere, oceans, rocks) are tightly coupled into one system, and that this system regulates conditions such as global temperature, ocean salinity and the composition of the atmosphere within ranges suitable for life.
Origins
James Lovelock arrived at the idea in the 1960s while working on NASA’s search for life on Mars. He reasoned that a living planet would have an atmosphere far from chemical equilibrium, as Earth’s is, with oxygen and methane coexisting. The novelist William Golding suggested the name of the Greek Earth goddess. From the early 1970s Lynn Margulis supplied the microbiology showing how organisms could carry out the regulation. Lovelock’s book Gaia: A New Look at Life on Earth (1979) brought the idea to a wide audience.
Cybernetic character
Gaia is homeostasis on a planetary scale: a network of negative feedback loops between life and environment. Critics, notably the biologists W. Ford Doolittle and Richard Dawkins, argued that such regulation would require planning or natural selection among planets. Lovelock answered with Daisyworld (1983, with Andrew Watson), a model planet where black and white daisies, each simply growing best at a certain temperature, stabilise the climate without any foresight.
Legacy
The stronger claims of the hypothesis remain contested, but its core idea, that life is an active part of the Earth’s regulation, helped found Earth system science. Gaia also shapes current thinking about climate feedbacks, tipping points and planetary boundaries.
Further reading
- James Lovelock, Gaia: A New Look at Life on Earth (1979)
- Tim Lenton and Andrew Watson, Revolutions That Made the Earth (2011)
Mentioned in
- Concept Autopoiesis
- Concept Homeostasis
- Person James Lovelock
- Person Lynn Margulis