The Gaia hypothesis ran into controversy from the outset. Lovelock decided that in order to answer his critics he needed somehow to simplify it without distorting it, for in doing so he would be able to create a mathematical model that would demonstrate his core proposition.
The result was Daisyworld, an imaginary world in which the main species is a daisy, but a daisy unlike the ones familiar to us in one crucial respect: these daisies are of different colours, some light, some dark and some of shades in between.
The world has one other notable feature: the sun that warms it is slowly and inexorably getting hotter (just as in our world – when life started well over 3 Billion years ago the sun was about 30% less luminous than it is now).
With his colleague Andrew Watson he created a computer stimulation and ran it from a point in the distant past, when the sun was less luminous and the earth’s surface was a lot cooler than it is now. This favoured the growth of the dark-coloured daisies, for the dark flowers absorbed the heat and therefore they were the ones to thrive in the cool conditions.
As the sun steadily got hotter, it was the white daisies that eventually came to dominate the world, as they naturally cooled themselves by reflecting the sun’s heat.
The point here is that the simple effect of reflection/absorption of the sun’s rays by different coloured surfaces (known as the albedo effect) profoundly influenced the temperature of the world’s atmosphere. It did so because the surfaces in question were living surfaces, which evolved over time and had the effect, first, of warming the planet, and then, over time, of cooling it. They acted as a thermostat, maintaining an equable temperature for life as a whole.
Thus, Lovelock sought to prove that Gaia did not need to be conscious in order to create conditions that were suited for life to thrive on a planet that was constantly changing (one of the main criticisms of his hypothesis was: how could billions of life-forms exert a life-enhancing influence on the planet unless they were collectively and consciously doing so?).
His concept was published in 1983 in a paper called “The Parable of Daisyworld”.
The image is from “Exploring the Dynamics of Earrth Systems, Dave Bice, Penn State University.
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