Adaptation, Evolution And Reproduction Of Gaia By The Means Of Our Species.

Nowadays, the idea that life affects the development of the planetary environment, and can, in turn, affect the future evolution of itself (in a coevolutionary way) is well-accepted. However, since the proposal of the Gaia hypothesis, there has been widespread criticism. Most of it is related to teleology, the absence of natural selection at a universal scale, and the lack of planetary reproduction. Some of the problems concerning the 'internal' logic of the idea have been resolved. Nevertheless, it is not sure whether Earth can be considered a unit of selection and (therefore) Gaia can adapt according to Darwinian evolution. After Lovelock and Margulis, Gaia has been considered a symbiotic planet composed of biotic (the biosphere) and abiotic (the geosphere-atmosphere) interacting with and coevolving elements. Here I propose why and suggest how a Gaian system should be considered alive in any evolutionary sense. I take into consideration the three principal criticisms and I analyse them following a logic-inductive reasoning. I use thought experiments and analogical arguments to analyse the rationale and the mechanisms by which Gaia evolves and may reproduce. This reasoning could allow rejecting the aforementioned criticisms as outdated and insufficient to discredit the main idea. I argue that without invoking teleology - so without any foresight or planning - a Gaian planet can be considered a coevolutionary system analogous to a multicellular body: a super-unit of selection. I describe different situations according to which Gaia is able to reproduce and transfer her planetary genome to other uninhabited or inhabited planets. Then I suggest that Gaia can face exclusion- competition-coexistence states depending on the fitness of her biota compared to those of the other reproducing biospheres. This demonstrates that Gaia can reproduce and evolve in competition-cooperation with other planets. Some deep implications arise from this evidence, also in light of the recent discovery of a new solar system with Earth-like planets by NASA.