A possible human counterpart of the principle of increasing entropy

• We propose a concept of entropy-like quantity in an isolated human system.
• The entropy-like quantity denotes the degree of uncertainty with arbitrage opportunities.
• We conduct a series of human experiments with four kinds of behaviors.
• The human system re-produces a principle, which is similar to the principle of increasing entropy in natural systems.
• The principle provides a different viewpoint to understand social human systems.

It is well-known that the principle of increasing entropy holds for isolated natural systems that contain non-adaptive molecules. Here we present, for the first time, an experimental evidence for a possible human counterpart of the principle in an isolated social system that involves adaptive humans. Our work shows that the human counterpart is valid even though interactions among humans in social systems are distinctly different from those among molecules in natural systems. Thus, it becomes possible to understand social systems from this natural principle, at least to some extent.