The Gaia hypothesis: named for the Greek Earth goddess Gaea, holds that the Earth as a whole should be regarded as a living organism and that biological processes stabilize the environment. First advanced by British biologist James Lovelock in 1969.
(NASA Thesaurus) The hypothesis that the Earth's atmosphere, biosphere, and its living organisms behave as a single system striving to maintain a stability conducive to the existence of life.
The Medea hypothesis: In The Medea Hypothesis, renowned paleontologist Peter Ward proposes a revolutionary and provocative vision of life's relationship with the Earth's biosphere--Using discoveries from the geological record, he argues that life might be its own worst enemy. This stands in stark contrast to James Lovelock's Gaia hypothesis--the idea that life sustains habitable conditions on Earth. In answer to Gaia, which draws on the idea of the "good mother" who nurtures life, Ward invokes Medea, the mythical mother who killed her own children. Could life by its very nature threaten its own existence?
According to the Medea hypothesis, it does. Ward demonstrates that all but one of the mass extinctions that have struck Earth were caused by life itself. He looks at our planet's history in a new way, revealing an Earth that is witnessing an alarming decline of diversity and biomass--a decline brought on by life's own "biocidal" tendencies. (Princeton University Review Press)
"Ideal types are used to simplify a complex reality."
"All theory, dear friend, is gray, but the golden tree of actual life springs every green."
When I consider the Gaia and Medea hypothesis's put forth by Lovelock and Ward I see it as a difference of emphasis and a point of what one highlights versus a right or wrong dichotomy. Life is a dynamic mix of life and death. Awesome and dreadful. Wonderful and horrific. Beauty and agony. Order and chaos. Beyond the dogma. To use an ancient roman god I would use a metaphor of the Janus god. The two faced god interlocked and connected. The two faces of Gaia and Medea are one. The Janus hypothesis.
Janus: Roman god of doorways and archways, after whom the month of January is named. Often depicted as a double-faced head, he was a deity of beginnings. He was one of the principal Roman gods, the custodian of the universe. Janus was usually represented with two bearded heads placed back to back so that he might look in two directions at the same time. Symbolic for entrances or exits-His chief function was as guardian deity of gates and doors.
Entrances and exits. Life and death. Evolution and extinction. The day and night exist in reference to each other. Gaia and Medea do not face in each other in conflict but attached to each other they face their gateways of life and death in unison. Another way to look at it is through the perspective of Cosmic Evolution when one considers the violence of exploding stars and how that brought about a process of new life birthing planets and new stars. Our Sun in our solar system and the Earth itself comes from a supernova. A violent death bringing new life. Medea working with Gaia in a dynamic mix of destruction and creation.