Geology Reference
In-Depth Information
ments and in the intestines of herbivores such as termites, cows, and even occasionally
omnivorous creatures such as us. Lovelock told NASA that the Viking mission would
not find life on Mars simply because its atmosphere, being mainly carbon dioxide, spoke
eloquently of a dead planet.
But the critical insight did not occur to him until he came across the puzzling geo-
logical fact that the proportion of oxygen in Earth's atmosphere has remained roughly
constant at habitable levels for the last 300 million years. As he wondered how this
constancy could possibly have arisen, a startling idea closed in on his conscious mind.
Surely, he mused, the amount of oxygen in the atmosphere should have varied unpre-
dictably over long stretches of geological time, as freshly minted oxygen and methane
consumed each other in a matter of days to give carbon dioxide and water? Just then, an
awesome realisation dawned in his keenly inquisitive mind. Perhaps life was somehow
involved in not just making the atmospheric gases, but also in
regulating their abund-
ance,
keeping them at levels suitable for life itself over vast periods of time. Lovelock
knew only too well how organisms perform similar self-regulatory manoeuvres within
their own bodies by keeping a whole host of substances such as blood sugar and hor-
mones at life-sustaining levels despite all sorts of stresses, perturbations and disturb-
ances. He had dared to think the unthinkable—that the planet is in essence a huge living
organism with its own remarkable emergent capacity for self-regulation. Here is how he
recounts how the moment of realisation came to him:
For me, the personal revelation of Gaia came quite suddenly—like a flash of enlightenment. I was in
a small room on the top floor of a building at the Jet Propulsion Laboratory in Pasadena, California. It
was the autumn of 1965 . . . and I was talking with a colleague, Diane Hitchcock, about a paper we were
preparing. . . . It was at that moment that an awesome thought came to me. The Earth's atmosphere was
an extraordinary and unstable mixture of gases, yet I knew that it was constant in composition over quite
long periods of time. Could it be that life on Earth not only made the atmosphere, but also regulated it—
keeping it a constant composition, and at a level favourable for organisms?
Lovelock had received two startling insights. It was as if he had been an explorer in a
far country who, reeling from his discovery of a wild sunlit river tumbling over a spec-
tacular waterfall, had then stumbled, awestruck, through an opening in the trees to find
yet another powerful cascade plunging over a precipice into the depths of the forest. The
first insight was that life had regulated the composition of the atmosphere over geologic-
al time; the second, a logical extension of the first, was that life must also have regulated
our planet's temperature.
Notice that the insights are described first of all in very general terms. Gaia (although
he had not yet encountered that name) was a “revelation” and “awesome thought”. This
suggests that a deep experience might have been involved, akin to Leopold's conversion
in the mountains of New Mexico, and indeed it was, but Lovelock's deep experience
