Is Earth Smart?

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 , and usually those heads sit on the shoulders of animals like