Sky & Telescope - July 2019 - 12

Can a Planet Think?
Due to one species - us - Earth's biosphere has begun to
resemble a human brain.
IN THE 1970 S , scientists James Lovelock

and Lynn Margulis proposed the Gaia
hypothesis, which likens our biosphere
to a self-regulating organism. In the
decades since, the idea that biological
evolution is inseparable from planetary processes became part of mainstream Earth-system science. Just as
an individual living thing such as a sea
slug can exhibit sophisticated internal self-regulation without needing
abstract thought, our biosphere may
help regulate the planet without any
self-awareness.
Yet sometimes I wonder.
Through our inﬂuence on our
planet's history, cognitive processes
have become, in a way, planetary processes. Humans are the ﬁrst geological
force to be aware of its own existence.
But beyond this, could there actually

be some emerging mind - and not just
metaphorically - that is global in scale?
Many have noted superﬁcial ways
in which the internet resembles a giant
brain, with myriad nodes exchanging
billions of signals. But several of our
other aggregate, global-scale activities
also involve the complex, planet-wide
interchanges of matter, energy, and
information we might expect from an
individual, self-regulating entity.
In the 1970s we humans saw that our
use of certain refrigerants was endangering our ozone shield. We thought
about it for a few years then stopped
using them. If an asteroid menaced
Earth now, we'd deliberate then swat
it away. And, in a painfully slow way,
we're realizing that our energy systems
threaten our well-being, and we're starting to seriously consider replacing them.

In other words, humans, working on
a global scale, are acting like a single,
sentient planet. We exhibit uniﬁed
behavior and respond to memories, lessons learned, and data gathered about
the situations we ﬁnd ourselves in.
Obviously there are many ways
in which none of this activity seems
like "planetary intelligence" - the
6,000-billion-trillion-kilogram rock we
live on isn't cogitating. And if humankind is a sensing, thinking, and acting
beast, it's quite sluggish, and perhaps
even borderline psychotic. All this
global behavior is plainly incoherent
and very slow to respond to perceived
danger. What we see is chaos, discord,
and noise. Yet is this really so different
from a human mind?
Imagine if you could make yourself
minuscule and descend into your own
brain in the midst of trying to make a
decision. What you'd observe might be
every bit as chaotic as our world. Yet
somehow out of all those competing
thoughts and ﬁring neurons comes a
pattern, and a decision is made.
The mechanics of decision-making
for groups is on some level not that
different than those of an individual
mind. Group members accept input and
apply some manner of reason and store
of memories and knowledge to determine how to act on that input. There
is a deliberative process, which may
involve conﬂict, competition, cooperation, and communication, ultimately
resulting in a course of action.
In the end, the similarities between
cognition, biological evolution, and
globalization might provide insight into
the nature of collective decision-making
on planetary scales. Maybe the Gaia
hypothesis is strangely correct. Maybe
the world didn't originally evolve with
purpose - but now, through our actions
and desires, it's becoming invested (or
infested?) with it.
Just a thought.
■ Astrobiologist DAVID GRINSPOON
is the author of Earth in Human Hands:
Shaping Our Planet's Future.

J U LY 2 0 1 9 * S K Y & T E L E S C O P E

A N TONIOK HR / ISTOCK / G E T T Y IM AG ES PLUS

COSMIC RELIEF by David Grinspoon

Sky & Telescope - July 2019

Table of Contents for the Digital Edition of Sky & Telescope - July 2019