On Gaia

Disclaimer: I am no authority on the subject. I am not responsible for any loss of life, property or sanity that results from this post.


When sometime ago I was doing this course (rather notorious in IIT) on "Technology, Development and Society" (don't ask me why), the professor took upon herself to explain to us the Gaia hypothesis. This hypothesis, immensely controversial, to say the least, states, very loosely speaking, that the whole of earth is a single organism, and like all other organisms it seeks to preserve itself. That sounds so intelligent-design-y right? I thought so too..

Then at the end of the course one of my classmates made a presentation on the Gaia hypothesis, and one slide really stuck in my head. It drew a distinction between Gaia and Darwin's natural selection, and I remember my classmate's words: she said that Natural selection was about adaptation; the Gaia hypothesis was about adaptation and change. The idea was simple: we have a tendency to view natural selection as individuals competing in a static environment. That however can at best be an approximation to the true situation: we don't just compete and adapt to the environment, we also change the environment itself.

How does that change things? Weirdly, when you endow living organisms with the power to change their own environment, what you often get is a remarkable stasis in the environment. There is this mathematical model called Daisyworld. It is a planet in which the only living organisms are two species of daisies: white daisies and black daisies. The white daisies can survive in warm climes and by reflecting the sunlight they reduce the temperature around them. The black daisies can live in the cold and by absorbing the sunlight they increase the temperature around them. Now consider a situation in which the sun is constantly coming closer to the planet. When the sun is far away, the black daisies dominate, and they make the planet warmer. As the sun comes closer, temperatures tend to rise, making it possible, then favourable for white daisies to grow; the white daisies dominate, bringing temperatures down. The result is that temperatures remain steady for most of the time, rising steeply towards the end.

Natural selection, and most of our scientific thought, tends to view the environment as separate from the living organisms. It is assumed to be like an infinite source or sink of resources, passively playing its part, merely providing the stimulus for life to evolve. The truth however is that the environment is inseparable from the organisms that it supports. All the daisies in the daisyworld example are linked with the environment, and with each other. The heat that one black daisy absorbs makes life harder for another black daisy sharing the environment, and easier for the white daisy. Although this simple, rather local effect is easy to grasp, it leads to rather counterintuitive global effects: the temperature of the world remains constant, as if there was an intelligent entity trying to control the environment, as if the planet was truly alive, trying to survive.

But is it really so counterintuitive? Consciousness itself arises in our heads from neurons that have no idea what we are thinking about. This queerly magical notion of control, this "I" whom we call intelligent is emergent from the behavior of innocent neurons, in the same way that the temperature of Daisyworld is emergent from the behavior of innocent daisies. In each case, each individual component is prohibitively simple, yet the system of interacting agents is prohibitively complex.

The fun part is that this interaction acts at so many different levels. The daisies interact with the environment to generate Daisyworld, cells interact with each other and the environment to give rise to the entity called a daisy, molecules interact with themselves and the environment to give cells their meaning, and so on and so forth. There is a whole web of interactions, and it doesn't go wide as much as it goes deep. I would think that this interaction is critical to explaining the complexity of the world we live in, but science has always striven to simplify, to reduce the complexity, and we have always abstracted away the rest of the world when dealing with any system of particles, considering it as constant. My feeling is that in doing so, in our quest to simplify, we might have approximated away the very basis of nature.