The Gaia hypothesis, or Gaia theory, is a hypothesis suggesting that everything which lives on Gaia interacts with their surroundings to form a symbiotic circle, where everything affects each other to continue the lifecycle of planet Earth.

The Gaia hypothesis was first developed by a man called James Lovelock, helped by a microbiologist called Lynn Margulis. A chemist, Lovelock came up with the idea as part of his work concerning the biosphere, and the chemical processes involved in that biosphere.

The Gaia hypothesis includes conjecture on the following subjects:

  • the biosphere,
  • the evolution of organisms within the biosphere,
  • the stability of global temperature,
  • the salinity of seawater,
  • the atmospheric oxygen levels, and more.

There are many criticisms concerning the initial Gaia hypothesis, mainly to do with its narrow scope. This has changed recently, however, by the hypothesis expanding to include more scientific fields. These fields include systems ecology and the earth sciences, among others.

The inclusion of a wider variety of fields has silenced much of the criticism, but there are still many complaints. Most of these complaints are about the Gaia hypothesis being outdated and not in line with current evidence.


The field of biogeochemistry has been doing work which seems to back up the Gaia hypothesis in that planetary homeostasis is a result of the actions of all organisms in contact with each other.

The hypothesis submits that everything reacts to each other in order to create a biosphere which is constantly in sync with itself. When organisms make changes, the biosphere changes to accommodate it, and vice versa.

According to the Gaia hypothesis, the earth is a self-regulating system. It constantly evolves to meet the changing needs of creatures within it. The hypothesis states that the earth creates the perfect environment for life to thrive within it.

The main point of the Gaia hypothesis is that organisms evolve along with the biosphere they live in. Lovelock had a lot of information to support this view when he worked on his idea. People have pointed out that many events within the historical narrative have challenged this.

The equilibrium of the world in the Gaia hypothesis has already been upended several times in the past. The mass extinction of the dinosaurs which took place at the end of the Cretaceous period is the main example.

In the Gaia hypothesis, the biosphere exists in a state of perpetual feedback. Both the existing organisms and Gaia herself evolve to meet the other’s needs. This leads them both to be more suited to living with each other. This is what leads to a stable environment since everything within the environment is in sync with everything else.

The conditions necessary for life on earth depend on the symbiosis of the biosphere. This process of evolving and stabilising is what keeps the planet’s equilibrium. The continual process controls the biosphere down to the water salinity and temperature.

Mythological origins

The very name of the Gaia hypothesis is due to the long-standing tradition of viewing the earth as a living being. In Greek mythology, Gaia is the literal personification of the earth, and this continued into the Roman mythological cycle as well.

It is this mythology which Lovelock drew on with the advice of his friend William Golding. The idea of Gaia is a fitting one for the Gaia hypothesis, suggesting that the biosphere is uniquely alive in its own way.

The Gaia hypothesis was born out of the centuries-long consolidation of geology into the science that we know it as today. James Hutton, from the eighteenth century, was convinced that geology and biology were somehow interlinked. His work centred around the idea that everything – from the crust of the earth to the organisms that walked across it – evolved at the same time.

Vernadsky, a physicist in the early twentieth century, where he studied the chemistry in the earth’s atmosphere. His work helped him realize that the oxygen, nitrogen and carbon dioxide which are in the atmosphere occur naturally. He then published several works on the process whereby organisms could direct and redirect a biosphere’s natural development.

Aldo Leopold built on this work through goals of environmental ethics and wilderness conservation. He centred his work around homeostasis and the idea that the world is alive as a means to move towards his goal of world preservation.


One of the most interesting influences on the Gaia hypothesis (as well as the environmental movement in general) is that of the Space race in the late twentieth century.

earthrise gaia hypothesis

Image by NASA/Bill Anders

A symbol of this is the photograph ‘Earthrise’, taken by one of the astronauts, is what really brought everyone together under the aegis of what the world looked like from the outside. The image of the world is what drove the Gaia hypothesis.

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