The Mysterious, Deep-Dwelling Microbes That Sculpt Our PlanetEarth's crust teems with subterranean life that we are only now beginning to understand.
...As I studied the interdependence of Earth and life, I continually returned to an ancient and controversial idea: that Earth itself is alive. It was not until the late 20th century that the idea of a living planet found one of its most popular and enduring expressions in Western science, the Gaia hypothesis. Conceived by the British scientist and inventor James Lovelock in the 1960s and later developed with the American biologist Lynn Margulis, the Gaia hypothesis proposes that all the animate and inanimate elements of Earth are "parts and partners of a vast being who in her entirety has the power to maintain our planet as a fit and comfortable habitat for life."
Lovelock published his first book on Gaia in 1979 amid a growing environmental movement. Although his ideas found an enthusiastic audience among the public, many scientists criticized and ridiculed them. Those who bristled at the notion typically made the same protestations: Earth cannot be alive because it does not eat, grow, reproduce or evolve through natural selection like "real" living things.
Yet there has never been an objective measure or a universally accepted definition of life. There are numerous examples of things we consider inanimate that have traits of the living and vice versa. Life is more spectral than categorical, more verb than noun. Life is not a distinct class of matter but rather a process — a performance. Life is something matter does.
Although science has not yet arrived at a fundamental explanation of the phenomenon we call life, many experts in the past century have favored a variation of the following: Life is a system that sustains itself. This defining capacity for active self-preservation and self-regulation emerges at many different scales: at the scale of the cell, the organism, the ecosystem and, I would argue, the planet.
Gaia still retains something of a stigma in mainstream science, but in recent decades opposition has waned significantly. Although the claim that Earth itself is a living entity remains controversial, some scientists embrace it, and others are increasingly open to it. The idea that life transforms the planet and is intertwined with its self-regulatory processes has become a central tenet of mainstream Earth-system science, a relatively young field that explicitly studies the living and nonliving components of the planet as an integrated whole. As the Earth-system scientist Tim Lenton has written, he and his colleagues "now think in terms of the coupled evolution of life and the planet, recognizing that the evolution of life has shaped the planet, changes in the planetary environment have shaped life, and together they can be viewed as one process."
Like many living things, Earth absorbs, stores and transforms energy. Earth has a body with organized structures, membranes and daily rhythms. From the raw elements of our planet have emerged zillions of biological entities that ceaselessly devour, transfigure and replenish its rock, water and air. Such organisms do not simply reside on Earth; they are literal extensions of Earth. Moreover, organisms and their environments are inextricably bonded in reciprocal evolution, often converging upon self-stabilizing processes that favor mutual persistence. Collectively, these processes endow Earth with a kind of planetary physiology: with breath, metabolism, a regulated temperature and a balanced chemistry. Earth is not a single organism or a product of standard Darwinian evolution, but it is nonetheless a genuine living entity, a vast interconnected living system.
One early metaphor Lovelock deployed to explain Gaia was a redwood tree. Only a few parts of a tree contain living cells, namely the leaves and thin layers of tissue within the trunk, branches and roots. The rest is dead wood. Similarly, the bulk of our planet is inanimate rock, wrapped in a flowering skin of life. Just as strips of living tissue are essential to keep a whole tree alive, Earth's living skin helps sustain a kind of global being. What Lovelock did not realize at the time, however, was that even Earth's seemingly inert skeleton of rock was far more porous and alive than most people believed...
https://www.nytimes.com/2024/06/24/magazine/earth-geomicrobiology-microbes.html?pvid=VDgZ2yPB5fHujEKWCW3U_Zdh&smid=em-share
