“What Is Life?”

The question “What is life?” was proposed as “An activity to convey the complexities of this simple question” by Prud’Homme-Généreux (2013). This activity was successfully carried out with freshman undergraduate students, but “could easily be adapted for a high school or even an elementary school audience.” I believe it is such a fundamental question that it probably should be introduced in some form as early as possible in biology classes and revisited periodically as students mature in their biological knowledge. For example, determining whether a plant or animal is living or dead sometimes depends on the environment (such as temperature or the availability of liquid water) or the technology (instrumentation sensitivity) used to detect metabolism. This ABT article cites a frozen frog (in “hibernation”) as a living organism, but does not list a desiccated plant seed as living. A frozen frog would not be able to survive thawing if...