The Meaning of Life

Abstract

Biology is unique among the sciences in being perhaps the only field in which there is no general agreement on the object of its study. As beginning biology students quickly learn, adding the suffix “-logy” to most words instantly creates an area of study. However, although most biologists come to appreciate the difference between ichthyology, parasitology, embryology, paleontology, and even malacology, many have difficulties when challenged with defining biology. Biology is the study of life, but what is life? Some people enumerate metabolism, reproduction, homeostasis, genetics, and other characteristics often listed in introductory textbooks, but such checklists only understate the difficulty of defining life. Just walk the halls of any biology department and ask whether viruses are alive. Attempting to define life evokes a sense of frustration in many biologists. Why define the obvious? Why complicate the simple? In this respect, defining life reminds one of Justice Potter Stewart's struggle to define pornography in Jacobellis v. Ohio, 378 US 184, 197 (1964). Like pornography, life may not present any easy shorthand definition, but most people feel that “they know it when they see it.” Such feelings are not imagined. Consider, for example, taking a group of students to an archeological excavation and asking them to identify human artifacts among the rock debris. Most would be able to recover some artifacts without much training. Based on past experience, they will have formed a mental reference of potential human artifacts. Comparisons to this reference clue the students and provide them with intuition as to what is an artifact. Of all of the possible random shapes that rock debris can achieve, the probability is simply too small that one could be shaped like an arrowhead. Thus, if it looks like an arrowhead, it is likely to be an arrowhead. In this case, it is not life that they discover, but manifestations of the human form of life. Nonetheless, the process could be the same if they were looking for life.

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