The primary understanding of life is as a biological organism that takes part in evolution. But this is a mistake. Sara Walker here argues our idea of what life is doesn't stand up, there are several counter-examples, and we can see life in a number of different and radical ways.

One of the most popular definitions for life circulating in scientific communities is that “life is a self-sustaining chemical system capable of Darwinian evolution.” This definition was first developed in an exobiology discipline working group organized by John Rummel, who at the time was manager of NASA’s Exobiology Program. Although the definition was developed under the auspices of a NASA working group, it is by no means the official NASA definition, as is sometimes claimed in popular news outlets. It’s not even necessarily a widely accepted definition.