Gaia Theory in Brazilian High School Biology Textbooks

Gaia theory proposes that a cybernetic system including the biota and the physicochemical environment regulates environmental variables at a global scale, keeping them within a range that makes Earth inhabitable by living beings. One can argue that this theory can play an important role in school science, since it bears upon current environmental problems, contributes to cross-disciplinary learning, and may help students understand the nature of science. Nevertheless, discourses about Gaia include both scientific and non-scientific ideas, and, consequently, this theory has been seen as pseudoscience, or even antiscience, as an unwarranted view, entangled with mysticism. But an informed view about the contributions and risks associated with Gaia as part of science education depends on a general analysis about the treatment of this theory in school knowledge. Here, we offer the first analysis of this sort, critically evaluating how Gaia is addressed in a representative sample of Brazilian textbooks (n = 18). We present data about the presence or not of Gaia theory among the contents covered by the textbooks, the presence of the claim that Earth is living, whether and how they use analogies to justify this claim, the discussion of evidence for and against Gaia, and the treatment of its relevance to current issues. Gaia theory is explicitly addressed in ca. 39% of the analyzed textbooks. There is a general script that the textbooks that explicitly name the theory follow when discussing Gaia. First, they argue that life affects the environment, and support this argument by means of examples, then, explain what the Gaia theory proposes, discuss evidence in favor either of the idea that Earth is living or Gaia theory in general, introduce one or more analogies to justify the claim of a living Earth, and, finally, offer remarks on the current importance of Gaia. Three analogies used by Lovelock himself were found in the analyzed textbooks, Gaia as a superorganism, the analogy between Gaia and a redwood tree, and between Gaia and the Greek goddess of Earth. The most frequent was the superorganism analogy. The idea of a control system including the biota and the physicochemical environment and any discussion about theoretical and empirical advances resulting from Gaia theory were absent from most analyzed textbooks, which focused mainly on the claim of a living Earth. Although Gaia can contribute to the understanding of environmental issues, the treatment found in most of the analyzed schoolbooks puts so much emphasis on the idea that Earth is living and is so close to an animistic understanding of the Earth system that it is likely that it will bring no true contribution to the development of adequate conceptions about that system and the connections between human activities and the environmental crisis.