The Earth alive
The concept of a living Earth has caused a lot of controversy, partly due to the different attributes and connotations given to this hypothetical life, partly because of the straightforward language used by Lovelock in his writings. For instance, evolutionary biologists such as the late palaeontologist Stephen Jay Gould and the ethologist Richard Dawkins attacked his statement in the first paragraph of his book (1979), that "the quest for Gaia is an attempt to find the largest living creature on Earth." James Lovelock sustains that agreeing on a rational answer is not possible because science has not yet formulated a full definition of life.
A basic criterion of the empirical definition of a life-form is its birth out of natural selection and its ability to replicate and pass on its genetic information to a succeeding generation. Dawkins stressed that, consequently, an argument against the idea that Gaia as a living organism is the fact that the planet is not the offspring of any parents and is unable to reproduce.
Lovelock, however, defines life as a self-preserving, self-similar system of feedback loops like Humberto Maturana's autopoiesis; as a self-similar system, life could be a cell as well as an organ embedded into a larger organism as well as an individual in a larger inter-dependent social context. The biggest context of interacting inter-dependent living entities is the Earth. The problematic empirical definition is getting "fuzzy on the edges": Why are highly specialized bacteria, such as E. coli, unable to thrive outside their habitat considered "life", while mitochondria, which have evolved independently from the rest of the cell, are not?
William Irwin Thompson suggests that the Chilean biologist Humberto Maturana and James Lovelock, with the deductive definition of autopoiesis, have provided an explanation for the phenomenon of life.[35] Reproduction becomes optional: bee swarms reproduce, while the biosphere has no need to. Lovelock himself states in the original Gaia book that even that is not true; given the possibilities, the biosphere may multiply in the future by colonizing other planets, as humankind may be the primer by which Gaia will reproduce. Humanity's exploration of space, its interest in colonizing and even terraforming other planets, lends some plausibility to the idea that Gaia might in effect be able to reproduce.