Scientists may have found the missing piece to the puzzle of the “Gaia hypothesis.” First proposed by James Lovelock and Lynn Margulis in the 1970’s, the Gaia hypothesis is an attempt to explain how Earth has managed to sustain life in the face of the multitudes of cosmic and terrestrial cataclysms that have befallen our pale blue dot throughout the approximately 3.8 billion years since our very first single celled ancestors started this whole mess.
Essentially, the Gaia hypothesis (named for the Greek goddess who personified our planet) states that organic life interacting with non-organic materials—like the rock that makes up Earth’s crust—creates conditions that allow life to persist. Another way to say it is that Earth functions just like any other multi-cellular organism, with self regulating processes and systems that make sure that the whole thing doesn’t fall to pieces the next time it gets smacked with a space rock or some of its constituent parts go rogue and start tearing up the joint.
The thought that we’re all cells in the larger organism that is our mother Earth is a beautiful idea, even if it does sound like something your buddy Kevin might say around a campfire at 4 AM. The problem with the Gaia hypothesis is that scientists had no testable ideas on how these processes of self-stabilization might work. In a paper published in the journal Trends in Ecology and Evolution, scientists at the University of Exeter and University of Southhampton say they have found a solution to the puzzle of the Gaia hypothesis.
Writing in The Conversation, co-authors of the paper Tim Lenton and James Dyke say that the key may lie in the concept of “sequential-selection”:
In principle it’s very simple. As life emerges on a planet it begins to affect environmental conditions, and this can organise into stabilising states which act like a thermostat and tend to persist, or destabilising runaway states such as the snowball Earth events that nearly extinguished the beginnings of complex life more than 600m years ago.
If it stabilises then the scene is set for further biological evolution that will in time reconfigure the set of interactions between life and planet.
So what about those destabilizing runaway states? How could that help explain the persistence of life? Well, sequential selection means that when something gets out of hand, Gaia has a way of taking out the trash, so to speak. Dyke and Lenton say that there’s a good chance spontaneous interaction works, but like all things, there are boundaries:
The chances of life and environment spontaneously organising into self-regulating states may be much higher than you would expect. If fact, given sufficient biodiversity, it may be extremely likely. But there is a limit to this stability. Push the system too far and it may go beyond a tipping point and rapidly collapse to a new and potentially very different state.
So, if the Gaia hypothesis is correct then it’s not that we need to worry about killing the planet—Earth has been around for far longer and been through way worse than we can throw at it—it’s that we need to worry about angering a vengeful nature goddess who’s back we happen to be riding upon, lest she decides to toss us off. That’s a comforting thought.