Wearing a black mariner’s cap and with a wall-to-wall bookshelf as a backdrop, Cambridge University professor Alan Macfarlane greets his social media audience with a soft ni hao – “Hello” in Chinese. In his latest video, Macfarlane follows this signature opening by thoughtfully answering a question pulled from the comments: why has making genuine friends become so difficult? Few would have expected an 84-year-old British anthropologist and historian from Cambridge University to become a social...