Complex sentence: In Toby Tyrrell's critique of the Gaia hypothesis he argues that Earth's climate system does not resemble an animal's physiological system: planets, unlike animals, are not products of evolution.
Split into simpler sentences: In Toby Tyrrell's critique of the Gaia hypothesis he argues that Earth's climate system does not resemble an animal's physiological system. Planetary biospheres are not tightly regulated in the same way that animal bodies are: planets, unlike animals, are not products of evolution.