The day our ancestors stumble upon chemistry

When the Mongols attack Eastern Europe (see far left), the battles are primarily decided by one powerful substance: adhesive. The Mongols conquer the world with horse bows glued together with a special paste of bone and cartilage. But they are not the first: “Adhesives have been around for at least 180,000 years,” says polymer chemist Ulrich Suter. Stone Age humans acquired the first all-purpose adhesive from birch tar, which is contained in the white bark of birch trees. This is the oldest chemical product created by humans. Researchers still wonder how they managed this, as the extract called betulin can only be distilled at temperatures around 750°F.