If you could send one piece of knowledge back to the Stone Age, what would it be? Assuming you’re making this decision for the good of humankind rather than scheming to make yourself rich, your answer will likely depend on your definition of human progress. You’ve got options. You can right a historic wrong. Introduce life-saving technology centuries early. Expedite a social revolution of your choice. You should try to offer something concrete and practical, but forget about everyday gadgets: What’s the point of a smartphone or ventilator if the tools and knowledge required for production are still millennia away?1 Better than a product is an idea. Press fast-forward on humanity’s greatest discoveries, and offer a head start on flight, radio or antibiotics. Or This story is from Kinfolk Issue Thirty-Seven Buy Now Related Stories Arts & Culture Issue 19 Going Incognito We all secretly wonder what mischief we’d make if invisible: When our identity is hidden, everything seems possible. Arts & Culture Issue 19 The Best Policy Sometimes we talk to each other without feeling heard. Honesty—a most intimate interaction—can be just as thrilling as its more devious inverse. Arts & Culture Issue 19 A Sense of Suspense With unhinged imaginations and mountains of cliff-hangers, the filmmakers behind the sci-fi podcast Limetown have all the makings of a scary story. Arts & Culture Issue 19 Like Clockwork In this new column about time, we learn how slipping off our watches makes us feel like deadline-damning renegades. Arts & Culture Music Issue 19 On a Grander Scale Malaysian singer-songwriter Yuna now may live on the opposite side of the globe, but she’s determined to evolve while staying true to her roots. Arts & Culture Issue 19 Neighborhood: Fire Stations The firefighting profession has evolved over time from Ancient Rome’s rudimentary bucket brigades to today’s sleek life-saving departments.