The surface temperature of a lifeless planet would have changed dramatically with the increase in luminosity of the sun over geological timescales; on Earth, it has remained remarkably constant around temperatures suitable for life (s Harvey, 2003).
Daisyworld is a simplified model of an imaginary planet with just two species of daisies, black and white in order to demonstrate the way it happens. The growth rate of the daisies depends on their local temperature but the daisies modify this due to the differences in the way of absorbing radiation; black daisies have low albedo i.e. reflectivity and thus they heat up easily. On the other hand, white daisies with higher albedo tend to reflect the sun's radiation.
The Gaia hypothesis (Lovelock, 1972, 1979, 1988) came into the scene with the problem of determining the possibilities of life on Mars1. To carry out the experiments, it was neither easy not necessary according to Hitchcock and Lovelock (1966), to go to Mars. They claimed that all that was required is determination of the composition of the atmosphere of Mars. The atmosphere of Mars should be at chemical equilibrium (which is true) in the absence of any form of life on the planet. Similarly, if the atmosphere were not at equilibrium just like Earth, then this would strongly support the possibility of life on mars.
Lovelock believed that the Planet Earth should be studied as an organism due to the analysis that the general activity of the planet can effectively indicate the existence of life on it. The characteristic properties exhibited by the living things like respiration, metabolism, self-regulation, irritability and reproduction can be studied for the determination of life. To consider earth as an organism is just a matter of choice of great researchers but it certainly posses many properties similar to organisms.
The key objections that have been raised to the Gaia hypothesis are based on the evolution theory. Arguments are there on the consideration of Earth as an organism believing that organism properties arise only through natural selection. There is no particular mechanism so that the Earth can maintain the favourable conditions for the biota and hence there is no need to consider the matter (Dawkins, 1982). Continuous arguments were present about the