The elastic, waterproof latex of tropical trees that began as a curiosity and became indispensable once vulcanization made it stable — rubber put the modern machine on wheels and sealed it watertight, and the world's hunger for it drove both an industrial transformation and one of the cruelest episodes of colonial extraction, the wild-rubber atrocities of the Congo and the Amazon.
A material that bounces, stretches, and keeps out water sounds harmless, even playful. Yet the demand for rubber helped put the world on wheels and, for a few decades around 1900, helped drive one of the deadliest forced-labor systems in colonial history. The same soft substance that cushions a car tire was once gathered by people working under the threat of mutilation and death. Rubber is one of the clearest cases of a useful thing whose usefulness was paid for in lives.