Gaia: a search for life.

(This is a post I wrote several weeks ago and somehow left in drafts by mistake. Only happened to find it now because I wished to refer to it. Ah well, brain cell degeneration seems to be a more serious problem than I realised.)

There is something very satisfying about finishing a book in a day. Since I am not a particularly fast reader that book has to be short; and one that fits this criteria very well is LOVELOCK AND GAIA: SIGNS OF LIFE by Jon Turney. It is such a sweetly-sized book - just over 150 pages that fit so nicely into the hand - giving a concise overview of Lovelock's concept of Gaia or the earth as a living organism.


Gaia is a term first suggested to Lovelock by his neighbour William Golding. It evokes the idea of Mother Earth: a being that can think and change deliberately to preserve herself. It is a weird idea but one I find attractive - if only as a springboard for fiction or analogy.

Lovelock (and Lynn Margulis, his collaborator) has modified his hypothesis gradually since he first wrote about it in the seventies. It was in response to some work that he did for NASA, answering the question: How do we detect life on other planets? Lovelock suggested that one possible method could be by detecting a decrease in disorder. Unlike a drop of ink that slowly disperses in the bowl of water 'life' takes the chaotic and assembles it into order. It enforces a new equilibrium to suit itself. It regulates and controls. Detect an ambiguous equilibrium and you have detected life. Mother Earth is an example of such an incongruous equilibrium - the presence such a reactive gas as oxygen in the atmosphere is odd and theoretically shouldn't exist at all - it is an indication that the earth (all of it) is alive.

The idea of the earth as an organism seems to have evolved (although I suppose I am using that term inaccurately, but I couldn't resist it since most of those against the theory were Darwinists) in the last ten years to become something the scientific establishment can accept much more readily; that of the earth as a complicated interdependent system involving the geological, biological, chemical and physical processes at work on the planet.

On the face of it this hypothesis seems to me to be common sense. At school we were taught about various cycles - the carbon, the nitrogen, the rock - and I suppose I'd always had the idea that these were just representatives of many cycles. But now I know through reading this book there are other cycles that have to be accommodated too: a sulphur cycle for instance, to explain the apparent discrepancy between the flow of sulphur compounds to the land to the sea, and form the sea to the land. It is not a great step to envisage them all being part of a complicated and poorly understood system - rather like the system of our bodies which I am learning is poorly understood too.

The book gives the social history of the idea, gracefully indicating how Lovelock grew with his idea too, allowing his ideas to soften a little so that they became more acceptable to the newer, younger scientists that have had to grow up with the reality of climate change.

DaisyWorld
One stage along the way appealed to me very much: the idea of a daisyworld. Lovelock envisaged a world covered in two sorts of daisies; some with black petals and some with white. At first the sun was cool and the black daisies proliferated, absorbing what radiation there was and keeping the world warm. Then, as temperatures rose, the white daisies took over this time reflecting the heat so that again the temperature stayed the same. This system started as a thought experiment that was quickly modelled on an early computer in the eighties. The computer showed that the temperature of such a system would stay fairly constant until the heat of the sun grew too hot and the system broke down and Lovelock was delighted. It was an indication that Gaia could keep herself in order, he thought.

According to Lovelock then, Gaia is in balance. But this balance is delicate. In this article (and his latest book THE REVENGE OF GAIA) he explains that the world, by rights should be hotter than it is and it is only life that has kept it at temperate temperatures for the last three and a half billion years. But Gaia is ill, he says, and it is up to all of us to try and find a cure before she becomes as lifeless as Venus.

LOVELOCK AND GAIA which was published in 2003 ends as it began with the search for life on other worlds. By sending out probes and sniffing the atmosphere of other planets we might learn our own fate. If we can detect ozone then that will be an indication of an atmosphere rich in oxygen and therefore life. If these planets tend to be orbiting old suns then maybe that indicates that life takes a long time to appear; but if the planets tend to be only around young suns then maybe life appears often and is usually transient. Or it could be that we find no ozone at all and we will know that Gaia is perhaps an only child without any sisters.