ABSTRACT
A Definition of Life (DoL) is needed more than ever before, for several reasons: to provide defendable objective criteria for searches for life on other planets, to recognize critical distinctions between machine life and robots, to provide insight into laboratory approaches to creating test-tube life, to understand the profound changes that occurred during the origin of life, and to clarify the central process of the discipline of biology. Using the database of organisms in the biosphere and non-living entities in the geosphere, a Generalized (G) definition is constructed. This is further Universalized (U) by eliminating biases reflective of the contemporary terrestrial biosphere being confined to narrow chemical constructs and restricted sources of energy. The resulting GU DoL is then evaluated against accepted standards and common usage, difficult cases, pedagogical value, as well as scientific specificity. All known attributes found in the diversity of life on Earth are derivable from the DoL, including the ability to evolve.
