SPEAKER_02: Amazing, fascinating stories of inventions, ideas and innovations. Yes, this is the podcast about the things that have helped to shape our lives. Podcasts from the BBC World Service are supported by advertising.
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SPEAKER_01: Things that made the modern economy with Tim Harford.
SPEAKER_00: The black and white photograph shows a man perched on the edge of a wooden deck looking down at two objects. At first, you can't take in what they are. In the background, the palm trees. Two other men, one with arms folded, the other with hands on hips, stare grimly at their friend. Or perhaps the photographer. It's hard to tell. That photographer was Alice Seely Harris. The year? 1904. The location? A missionary outpost in Baringa, in what was then called the Congo Free State. The man's name was Nsala. As he explained to Alice, his wife and children had just been killed. And here, he told her, opening up a bundle of leaves was the proof. All that the attackers had left of his five-year-old daughter, Boali. Alice's photograph of Nsala, looking at his daughter's severed hand and foot, caused an uproar back in Europe. And she found no shortage of other brutal sites at which to point her Kodak camera. Printed in pamphlets and displayed at public meetings, Alice's harrowing images formed the world's first photographic human rights campaign. They helped build public pressure that eventually forced Belgium's King Leopold to loosen his grip on the colony famously depicted in Joseph Conrad's novel, Heart of Darkness. As the main character, Kurtz, put it, the horror. But why was Leopold's Congo so horrific? Rewind seven decades. To New York, 1834. An impoverished, unwell, but preternaturally optimistic young man is knocking on the door of the Roxbury India Rubber Company. Charles Goodyear had landed in Detters Prison when his family's hardware business went bankrupt, but he was sure he could invent his way out of financial trouble. His latest idea? An improved kind of air valve for inflatable rubber life preservers. Goodyear was in for a surprise. The manager loved his valve, but confessed that his company was on the verge of ruin. He wasn't alone. All over the country, investors had sunk money into this miraculous new substance, stretchy and pliable, airtight and waterproof, but now it was all going horribly wrong. Actually, rubber wasn't exactly new. It had long been known to South Americans and first reported by Europeans in the 1490s. The natives made a kind of wax from trees that give milk when cut. That milk was latex. It comes from between the inner and outer bark. Bits of rubber made their way to Europe, but were mostly a curiosity. In the 1700s, a French explorer brought the name Caoutchouc from a local language. It meant weeping wood. By the 1820s, rubber was attracting serious interest. More and more was being shipped from Brazil and made into coats, hats, shoes and those inflatable life preservers. Then came a really hot summer and entrepreneurs watched aghast as their inventories simply melted into foul-smelling goo. Goodyear saw his chance. A fortune awaited whoever could invent a way to make rubber cope with heat and cold, which made it brittle, and Goodyear was the man to do it. True, he had no background in chemistry and no money, but why should that stop him? For years, he dragged his wife Clarissa and their growing brood from town to town, renting ever more in salubrious houses, pawning their dwindling stock of possessions, running up debts and intermittently being hauled off to debtor's prison, but always just about managing to find some new relative to sponge off or an investor to convince that a breakthrough was just around the corner. When Clarissa wasn't trying to feed the children, Charles commandeered her saucepans to mix rubber with, well, anything he could think of. Magnesium, lime, carbon black. In the end, he found the answer. Heat the rubber with sulphur. It's a process we now call vulcanisation. Sadly for the long-suffering Clarissa, it led to her husband borrowing yet more money for lawsuits to try to protect his patents. When he died, he owed $200,000. But Charles' doggedness had put rubber at the very heart of the industrial economy, in belts and hoses and gaskets, sealing, insulating, absorbing shocks. In the late 1880s, a Scotsman living in Ireland supplied the killer app, the pneumatic tyre. Demand for rubber boomed. Europe's colonial powers set about clearing vast areas of Asia to plant Hevere Braziliensis, more widely known as the rubber tree. But those new rubber tree plantations would take time to grow, and hundreds of other plants also produced latex in varying quantities, even the humble dandelion. In the Congo's rainforest were vines that could be tapped to meet demand right now. How to get that rubber, as much and as quickly as possible? In the absence of scruples, the answer was distressingly simple. Send armed men to a village. Kidnap the women and children, and if their menfolk didn't bring back enough rubber, chop off a hand or kill a family. Some things have changed since Nsala met Alice Sealy-Harris in Beringa. More than half the world's rubber now comes not from weeping wood, but gushing oil. Attempts to make synthetic rubber began as the natural stuff grew popular and took off during World War II. With supply lines from Asia disrupted, America's government pushed industry to develop substitutes. Synthetic rubber is often cheaper and sometimes better. For example, for bicycle tyres. But for some uses, you still can't beat a bit of heavier Braziliances. About three quarters of the global rubber harvest goes into tyres for heavier vehicles. And as we make more cars and trucks and planes, we need ever more rubber to clothe their wheels. That's not without problems. The rubber tree is thirsty. Environmentalists worry about water shortages and biodiversity as Southeast Asia's tropical rainforest increasingly gives way to plantations. It's happening in Africa too. Travel a thousand kilometres through the rainforest from Beringa, for example, bearing west and slightly north, and you'll come to Mayo Masala in Cameroon. Nearby, the world's largest rubber processing company, majority owned by the Chinese state, is clearing thousands of hectares for rubber trees. The company says it's committed to ethical sourcing. Villagers say they haven't been properly compensated for the loss of their lands. So rubber is still causing controversy. But now it's cutting down trees, not cutting off hands. It is progress of a sort.
SPEAKER_02: We read about rubber in the Congo in Adam Hochschild's book, King Leopold's Ghost.
SPEAKER_01: For a full list of our sources, please see bbcworldservice.com slash 50things. I like that. I don't think I like that. This is the sound of crowd science. Those very alarming sounds. It's quite normal.
SPEAKER_02: This is what women want. They want a man that can eat a stick. I have a brilliant trowel. What you should see now is a cloud. No way. Each week, the CrowdScience podcast answers your questions about life, Earth and the universe. Are there foreseeable limits to knowledge?
SPEAKER_00: It's an excellent question. Actually, it's a very deep question. With the help of scientists
SPEAKER_02: around the world who are trying to find nuances themselves, we think that people have a little more control over their brainwaves than they think they do. That's CrowdScience from the BBC World Service. We smash things together and we'll see what happens. Just search for CrowdScience wherever you get your podcasts. You got brain freeze.
