'Gaia: The Practical Science of Planetary Medicine': A review of James Lovelock's book by Bert Jenkins. Gaia Books Limited, revised edition, 2000

Gaia offers us a unique image of the Earth as a living planet. This becomes apparent when one sees a photograph of our blue planet floating in space for the first time where its oceans, continents and icy poles stand out distinctively. In contrast to a similar photograph of another planet from our solar system, all of which are expected to be dead, we see the Earth as a living planet of rock that has an atmosphere containing oxygen, with water being produced on its surface. The Earth is alive; it is inhabited by organisms that combine in various ways to function as ecosystems within that green-blue layer we call the biosphere. In essence, Gaia offers us a means of understanding the Earth as a living planet that is capable of regulating its climate and maintaining favourable environmental conditions conducive to life. This process involves a double feedback loop - life on Earth shapes the physical and chemical environment that supports life, which in turn interacts with living organisms, influencing their evolution and natural selection. In this way, according to Lovelock and his colleagues, organisms are closely coupled to the evolution of the physical and chemical environment in which they live and interact - a never ending reciprocity - life in the biosphere modifies the physical-chemical environment and adapts to it in the process, and in turn 'the environment' supports life. The physical-chemical world and life on Earth are interconnected in a seamless whole - Gaia. Gaia is both the cradle of evolution and the museum of biophysical environmental change on Earth.