What Is Life?

I just read a really interesting essay by Carl Zimmer on how to define life, or whether a definition matters. The piece exposes the litany of definitions of life -- life must transform carbon dioxide, or contain membranes, or contain DNA, or it must evolve -- within the scientific community. It also exposes our curious current state of affairs, where we spend so much time arguing over issues, like stem cells and abortion and genetically modified foods, to which the meaning of life is crucial, yet we cannot actually agree on what life is.

Zimmer goes on to explain the platform of Carol Cleland, an astrobiological philosopher who argues a comprehensive definition of life is in fact unnecessary to our study of life. So much of the universe is yet undiscovered that we are limiting ourselves to arbitrary terms until we increase our sample size. In other words, we cannot purport to define life until we confront forms of life radically different from what we know here on Earth. Until then, we risk overlooking that which is life, perhaps bizarrely so, due to our possibly narrow constraints. This view commonly plays out with regard to viruses -- Scientists intensely debate whether or not viruses are living things, yet biologists continue to study viruses in their labs.

My favorite part of the essay discussed the origin of the debate on the meaning of life. It turns out that the instigator was not a biologist, but rather a physicist named Erwin Schrodinger. (Physics students around the world love and hate Schrodinger. At the same time). Schrodinger wondered how life seemed to violate the laws of physics: While everything else in the universe tends toward entropy, life is based on order, from ecosystems down to molecules. ...What a wonderful idea!

read The Meaning of Life