Tanzania, Sept. 2 -- Dar es Salaam. When most people throw away an old mobile phone, laptop or circuit board, they rarely think about where it goes next.

For Dr Samwel Moses Ntapanta, that is precisely where the story begins.

The Tanzanian anthropologist has followed the afterlife of things that others discard, from electronic waste piling up in African cities to the informal networks of workers who extract value from it, for nearly two decades.

More recently, his research has taken a digital turn, towards Bitcoin and cryptocurrencies and the ways people in the Global South are using them to navigate economies where conventional financial systems can be uncertain or inaccessible.

The subjects may appear unrelated but for Dr Ntapanta, ...