Joshua Greene asked participants how they would respond in two situations. In the first, they are watching five people in a trolley rolling down a railway track towards a cliff edge. They can save the five by throwing the lever of a set of points to divert the trolley—but doing so will kill a person…

Satellite images taken this year and 20 years ago show that the desert is in retreat thanks to a resurgence of trees. They are mainly ana trees (Faidherbia albida), a type of acacia. Wherever the trees grow, farming can resume. Tree planting has led to the re-greening of as much as 3 million hectares of…

Gunpowder, printing, magnetic compass , silk, porcelain, as well as the breast strap and horse collar (massively i mproved efficiency of horse power eg for ploughing cf oxen).  Not nearly as i mportant within China – gunpowder was not develop e d i nto weapons because politically very stable, printing was the exclusive skill of…