Using the Gaia Hypothesis to Synthesize an Introductory Biology Course

Abstract

The Gaia Hypothesis was first stated in the literature in 1972 when James Lovelock proposed that the biosphere is an adaptive control system that can maintain the Earth in homeostasis (Lovelock 1972, 1990). In its infancy the idea was controversial because it invoked the interpretation that the Earth acted like a living organism. The extension of life characteristics to the Earth was a major source of objections made by scientists. Today, after two decades of refinement and revision, the hypothesis no longer describes the Earth as a superorganism (Lovelock 1987, 1990). The main concept emphasized by the hypothesis is global systenms interactions and feedback mechanisms between the living and nonliving processes that take place on Earth. These ideas are now part of mainstream research efforts (Kerr 1988). A study of the Gaia Hypothesis in a biology course illustrates to the students the development of a current scientific hypothesis, and the creative integration between different aspects of biology and between biology and other disciplines which often result in the development of new and novel hypotheses. This exercise can be used as a specific implementation of teaching methods addressed by Coletta (1992) and Fortner (1992) which emphasize both the interdisciplinary nature of science and a planetary perspective of biology. Prior to studying the Gaia Hypothesis, students should be introduced to the topics most relevant to the hypothesis, to relationships between the topics and to the process of scientific investigation. These requirements are usually accomplished near the end of a course, therefore the Gaia Hypothesis activity can be used as a course summary activity. Topics most relevant to the Gaia Hypothesis include: ecology, natural selection, evolution, origins of life on Earth and factors leading to diversity, genetics, cell structure, photosynthesis, cellular respiration, biogeochemical cycling, geological time scales and plate tectonics. The theme during the course was that life on Earth is dynamic in time and space. Students examined all levels of biological organization specifically, but were reminded to keep in mind the broader context of interactions between pieces of living systems and the entire system. It is helpful to use a textbook that also highlights connections between subject matter. Textbooks accomplish this by a variety of techniques. Text illustrations, twopage essays preceding the standard text material and highlighted boxes in each chapter often work together to present the specific chapter topic in a broader perspective. Instructors can take advantage of this organization to discuss that broader view of specific material. In addition, accompanying instructors manuals, resource guides, or other ancillary materials are often appropriate to introduce students to a holistic viewpoint. I selectively drew upon a combination of the above to provide examples of relationships between topics. In addition to the subject matter there must be constant attention to guiding the students' understanding about the process of science. The majority of textbooks and lab manuals do not develop students' skills in scientific thinking (Gibbs & Lawson 1992). It is therefore the instructor's responsibility to provide continuing scientific thinking activities that are associated with the course material. The variety of ways to accomplish this have been the topic of articles in this journal and related publications. A sample of the sources that have been helpful to me include Middleton (1990), Carter and Mayer (1988), Uno (1989), Lawson et al. (1990) and references contained in those publications. These all contain instructions about how to incorporate an inquiry approach to the biology curriculum and have students do critical evaluation of current research to contrast and compare with text presentation.