Adam Frank, Sara Walker, and David Grinspoon write:

Almost a century ago, the revolutionary idea of the biosphere gained a foothold in science. Defined as the collective activity of all life on Earth—the tapestry of actions of every microbe, plant, and animal—the biosphere had profound implications for our understanding of planetary evolution. The concept posits that life acts as a potent force shaping how the planet changes over time, on par with other geological systems like the atmosphere, hydrosphere (water), cryosphere (ice), and lithosphere (land). Essentially, life has the capacity to hijack Earth’s evolution and, perhaps, steer its fate. The biosphere tells us that once life appears in a world, that world can take on a life of its own.

This idea first came as a shock to many researchers. Over the years, however, it has become central to Earth science, deeply influencing how we see life interacting with our planet, and our ideas about what life might do to other planets in the universe. As our understanding of the biosphere’s influence has deepened, it has also pointed to a provocative question—one much less explored. If a planet with life has a life of its own, can it also have a mind of its own?

Granted, any notion of a planetary mind might seem like New Age “woo.” Intelligence tends to be conceived of as something that happens in individual heads, and usually those heads sit on the shoulders of animals like humans. But over the past two decades, evidence for collective, distributed intelligence has appeared in a wide array of creatures and a staggering variety of scales, often in forms utterly different from our usual conception of “smart.” Bees and other eusocial insects, for instance, clearly show evidence of collective intelligence. A single bee holds only a small amount of information about the world, but its colony as a whole knows and responds to the environment. Or consider trees’ root systems, which connect to one another through underground strands of fungus, creating a kind of forest nervous system. Such fungal networks allow forests stretching hundreds of miles to recognize and respond to changing conditions. In this way, some have posited a kind of “green mind” distributed across space and time.

Going so far as to account for the collective intelligence of all life on the planet is, admittedly, an audacious use of the concept. But over the past couple of years, we—the authors of this article—decided to give it a shot. Our work has been a thought experiment, one that plays with ideas that science understands but extends them to confront a stark reality: Humanity stands at a most precipitous moment in both our and our planet’s evolution. We have discovered that the universe is teeming with worlds, many of which might host life and even intelligence. At the same time, our own world is in peril, caught in a climate crisis brought on by our supposed advancement as a civilization. [Continue reading…]