This course explores the prevalence, impact, and history of the associations between organisms (including human beings), from the very large to the microscopic, throughout the biosphere. A growing paradigm shift in science places diverse associations between organisms as central to evolutionary theory and life on Earth: not so much competition among organisms, but complex ¿networking¿ between them. The course examines relationships between organisms through this lens, including examples such as crustaceans that replace the tongues of fish, the tiny ¿wildlife¿ that lives on and within human beings, and the fact that life as known on Earth has resulted from ancient symbioses. Students develop skills in evaluating, discussing, and presenting concepts relating to symbiosis and parasitism, from historical, philosophical, and scientific viewpoints. Affiliate department: Biology.