The Gaia hypothesis, also called the Gaia theory or the Gaia principle, was formulated in the 1970s by chemist James Lovelock. The theory proposed that the conditions for life on Earth were maintained by the interaction of living organisms with inorganic processes.
The hypothesis was initially criticized for going against Darwin's principles of natural selection and, even though later refinements aligned it with fields such as biogeochemistry and ecology, the theory continues to attract criticism by scientists. Many today believe it to be at best weakly supported or at worst completely at odds with available evidence.
Selection by survival alone
Now a study published in the journal Trends in Ecology and Evolution is offering new hope for the controversial theory. A team of University researchers proposes that Earth's stability could originate from a “sequential selection” featuring short-lived destabilizing planetary situations.
These unstable circumstances only last until further change engenders yet another stable situation which persists. Every time this happens, the system finds the time to further accumulate more stabilizing qualities, a process the scientists are calling “selection by survival alone.”
“We can now explain how the Earth has accumulated stabilising mechanisms over the past 3.5 billion years of life on the planet.”
“We can now explain how the Earth has accumulated stabilising mechanisms over the past 3.5 billion years of life on the planet,” said Professor Tim Lenton of the University of Exeter in a statement. “The central problem with the original Gaia hypothesis was that evolution via natural selection cannot explain how the whole planet came to have stabilising properties over geologic timescales.”
The scientists are suggesting that it is at least two simpler mechanisms that are cooperating to produce Earth's self-stabilizing properties. The planet's system feedbacks themselves are what produce the conditions required for the successful combinations of macroevolutionary innovations.
“As well as being important for helping to estimate the probability of complex life elsewhere in the universe, the mechanisms we identify may prove crucial in understanding how our home planet may respond to drivers such as human-produced climate change and extinction events," said study co-author Dr James Dyke, of the University of Southampton. If proven to be correct, the theory may also bring a dire warning.
A planet pushed to its limit
When presenting the Gaia hypothesis, Lovelock had also argued that humans were pushing earth to its limit by destroying its rainforest "lungs" and filling it with carbon dioxide.
The chemist had already predicted we would head towards a very hot world unsuitable for most life forms and, although he stipulated the planet would eventually rebalance itself, he feared it would be too late for humans.
So far, there may be some evidence of Earth already attempting to restore stability and balance through its feedback loops. For instance, as atmospheric carbon dioxide levels have severely increased, so has the amount of carbon-capturing algal blooms in the ocean.
“We can learn some lessons from Gaia on how to create a flourishing, sustainable, stable future for 9-11 billion people this century," added Lenton. Let's hope we do it in time!
Via: University of Exeter