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 36 Trivial Matters On the uses of useless knowledge. Arts & Culture Issue 27 Akram Khan On the uneasy dance between knowledge and information. Arts & Culture Issue 47 Alice Sheppard On dance as a channel to commune with the body—even when it hurts. Arts & Culture Issue 47 Dr. Woo Meet the tattoo artist who's inked LA. Arts & Culture Issue 47 Walt Odets The author and clinical psychologist on why self-acceptance is the key to a gay man's well-being. Arts & Culture Fashion Issue 47 A Picture of Health Xiaopeng Yuan photographs the world’s weirdest wellness cures.