Monday, June 2, 2008

Talk: Victoria Johnson

Victoria Johnson: Rubber

The Para rubber tree, Hevea brasiliensis, is a tree in the family Euphorbiaceae. It grows to about 30 meters, and is endemic to the Amazon rainforest. It has had a huge economic impact as the source of natural rubber. Latex, the source of natural rubber, is also found in other plants (tens of thousands of species), and may be a defense against insect herbivory. Latex is produced by secretory cells called lactifers, located in the inner bark of the tree. Latex vessels spiral up the tree in a layer outside the cambium. Latex can be extracted by cutting with machetes or more sophisticated rubber tapping techniques. Unlike many latex-producing plants, the more damage that is done the more latex flows, making the rubber tree much easier to harvest latex from than other species; the rubber tree is responsible for 98% of the world's natural rubber harvest. The latex is then collected, preserved and stabilized. The wood of the tree, called parawood or rubberwood, is an ecologically sustainable tropical hardwood used for furniture. Cultivation of rubber trees is made more difficult by South American leaf blight, a fungal disease caused by the native ascomycete Microcyclus ulei; this fungus has prevented commercial-scale plantations in South and Central America, but is still absent from Asia.
The Para rubber tree was not domesticated in Brazil, but the Amazonian natives harvested the wild plants. Amazonian Indians leached poison from Para rubber tree seeds and ate them; the cooked seeds are edible. Some Amazonian Indians dipped their feet into latex and dried them over a fire to create perfectly sized sneakers. The waterproofing qualities of rubber were discovered by Europeans on a French expedition to the New World; de la Condamine documented rubber being used for torches, bottles and shoes by natives in Ecuador. Rubber was exported from tropical zones to Mesoamerica. In the Mesoamerican ball game, the ball was solid rubber, weighed up to five pounds, and was about six inches in diameter. Europeans initially believed the bouncing balls were bewitched or inhabited by spirits. The Olmecs (the "rubber people") were the first to cultivate the rubber tree, and are often given credit for having invented the ball game. Rubber balls were symbolic of fertility, and the Aztecs and the Maya equated latex with blood and semen.
Columbus saw rubber in the West Indies, and saw games with bouncing rubber balls in Hispaniola, between 1492 and 1496. Rubber was introduced to Britain in 1730, but it took a long time to catch on, partly because of the chemical instability of natural rubber. In 1827 Brazil exported 31 tons of natural rubber; in 1830 Brazil exported 156 tons. In 1834-1839 vulcanization was developed by Charles Goodyear, making the rubber more stable (and harder), and rubber took off. In 1840 Brazil exported 388 tons, in 1850, 1467 tons, in 1860, 2673 tons, in 1870, 6591 tons. Manaus was at the center of this trade; the rubber export from Brazil went through Manaus, and it caused a huge economic boom. The British were quite unhappy about the Portuguese monopoly on rubber, and Sir Henry Wickham managed to cultivate rubber trees from seeds (smuggled? stolen?) from Brazil. The British began growing rubber trees in tropical spots in the British empire, such as Sri Lanka and Singapore. In Brazil, meanwhile, 8680 tons were exported in 1880, 19000 tons in 1890.
The years of 1890-1920 was the "rubber boom," the Golden Age of Manaus. 120,000 native slaves were used to collect latex, and the rich rubber barons built huge colonial mansions, paved the streets, ran streetcars, introduced electricity, and so forth. The opera house in downtown Manaus dates to this period. The effect on the native people of Brazil was quite negative; brutal labor practices, debt and introduced alcohol were used to control them, and the rubber trade fragmented their society. The population of native peoples dropped precipitously.
But in 1898 the British established a successful rubber tree plantation in Malaysia (after much struggling). The British had an advantage because of the lack of the South American leaf blight in Asia, and rubber prices began to drop. In 1902 rubber plantations were established in India. The maximum output of rubber from Manaus was in 1906-07, when 30,000 tons were exported; things went downhill from there.
From 1920-1945 Henry Ford established Fordlandia, a large rubber tree plantation in Brazil, in an attempt to obtain his own rubber for car tires. It failed, as did all later attempts at large-scale rubber cultivation in Brazil. Ford was oblivious to Brazilian culture; he forced his workers to wear ID badges, eat hamburgers, work 9 to 5 days, and did not allow drinking or smoking. A worker rebellion in 1930 had to be subdued by the Brazilian army. Ford lost $20 million on Fordlandia before giving up.
During World War II the Japanese had control over most areas suitable for growing rubber trees, and the other powers struggled to find alternatives; the Germans experimented with harvesting latex from dandelions! From 1941 to 1953 Richard Evans Schultes, the "Father of Ethnobotany," was sent to South America to find a reliable source of rubber for the U.S. war effort. He remained to discover and catalog 25,000 new botanical species. In 1945 synthetic rubber was developed, made from gas or oil.
In the 1960s world natural rubber prices collapsed,and many landowners in Brazil sold to ranchers. In the 1970s Chico Mendes, a rubber tapper and unionist, united the rubber tappers and opposed the loss of rainforest to cattle ranches. By 1988 Mendes has reached such prominence and importance that he was assassinated by the cattle ranchers; but the seringeuiros, the rubber tappers of Brazil, became heroes in popular culture.
Today, worldwide rubber production is 9.7 million tons. Thailand, Malaysia, and Indonesia are the prime rubber producers in the world, followed by Sri Lanka, India, Liberia, and Nigeria. 90% of world rubber production comes from Asia, because of the South American leaf blight. In 2007, Brazil produced about 1% of the world's natural rubber, which is less than Brazil itself consumes.
Rubber today is used in tires, toy balloons, water bottles, condoms, carpet underlay, belts, wire cables, hoses, rubber bands, erasers, rubber stamps, footballs, golf balls, tennis balls, gloves, Wellington boots, Mackintoshes, waterproof fabrics, rubber bullets, rubber duckies... About 40% of the world's rubber is natural rubber, while the other 60% is synthetic; natural rubber has some properties that synthetic rubber does not, so it is still needed for some uses. 75% of all rubber is used in tire manufacturing.

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