India, May 23 -- It's one of the first things to go in an apocalypse, or so all the science-fiction suggests.

In the slow-burn but often-riveting second season of the streaming series Paradise, for instance, a mega-volcano has shut out the sun; civilisation has fallen; it is three years on. At swap meets held in high-school gyms, people trade precious objects such as tools, bullets, batteries. Items most in demand include any forms of food from the before world, including sachets of ranch dressing.

In Cormac McCarthy's masterful 2006 novel The Road, a wallet offers a chilling reminder of how little inherent value money has, outside the systems that hold it up.

In the real world, even centuries after money took over most trade, alternat...