A Primer on Building Life-Like Systems

The quest to understand life and recreate it in vitro has been undertaken through many different routes. These different approaches for experimental investigation of life aim to piece together the puzzle either by tracing life's origin or by synthesizing life-like systems from non-living components. Unlike efforts to define life, these experimental inquiries aim to recapture specific features of living cells, such as reproduction, self-organization or metabolic functions that operate far from thermodynamic equilibrium. As such, these efforts have generated significant insights that shed light on crucial aspects of biological functions. For observers outside these specific research fields, it sometimes remains puzzling what properties an artificial system would need to have in order to be recognized as most similar to life. In this Perspective, we discuss properties whose realization would, in our view, allow the best possible experimental emulation of a minimal form of biological life.