Inca Leapt Canyons With Fiber Bridges

MIT Students Plan to Stretch 60-Foot-Long Fiber Bridge Between Campus Buildings

Conquistadors from Spain came, they saw, and they were astonished. They had never seen anything in Europe like the bridges of Peru. Chroniclers wrote that the Spanish soldiers stood in awe and fear before the spans of braided fiber cables suspended across deep gorges in the Andes, narrow walkways sagging and swaying and looking so frail.

Yet the suspension bridges were familiar and vital links in the vast empire of the Inca, as they had been to Andean cultures for hundreds of years before the arrival of the Spanish in 1532. The people had not developed the stone arch or wheeled vehicles, but they were accomplished in the use of natural fibers for textiles, boats, sling weapons — even keeping inventories by a prewriting system of knots.

So bridges made of fiber ropes, some as thick as a man's torso, were the technological solution to the problem of road building in rugged terrain. By some estimates, at least 200 such suspension bridges spanned river gorges in the 16th century. One of the last of these, over the Apurimac River, inspired Thornton Wilder's novel "The Bridge of San Luis Rey."

Although scholars have studied the Inca road system's importance in forging and controlling the pre-Columbian empire, John A. Ochsendorf of the Massachusetts Institute of Technology here said, "Historians and archaeologists have neglected the role of bridges."

Ochsendorf's research on Inca suspension bridges, begun while he was an undergraduate at Cornell University, illustrates an engineering university's approach to archaeology, combining materials science and experimentation with the traditional fieldwork of observing and dating artifacts. Other universities conduct research in archaeological materials, but it has long been a specialty at MIT.

Students here are introduced to the multidisciplinary investigation of ancient technologies as applied in transforming resources into cultural hallmarks from household pottery to grand pyramids. In a course called "materials in human experience," students are making a 60-foot-long fiber bridge in the Peruvian style. On Saturday, they plan to stretch the bridge across a dry basin between two campus buildings.

In recent years, MIT archaeologists and scientists have joined forces in studies of early Peruvian ceramics, balsa rafts, and metal alloys; Egyptian glass and Roman concrete; and also the casting of bronze bells in Mexico. They discovered that Ecuadoreans, traveling by sea, introduced metallurgy to western Mexico. They even found how Mexicans added bits of morning-glory plants, which contain sulfur, in processing natural rubber into bouncing balls.

"Mexicans discovered vulcanization 3,500 years before Goodyear," said Dorothy Hosler, an MIT professor of archaeology and ancient technology. "The Spanish had never seen anything that bounced like the rubber balls of Mexico."

Heather Lechtman, an archaeologist of ancient technology who helped develop the MIT program, said that in learning "how objects were made, what they were made of and how they were used, we see people making decisions at various stages, and the choices involve engineering as well as culture."

From this perspective, she said, the choices are not always based only on what works well, but also are guided by ideological and aesthetic criteria. In the casting of early Mexican bells, attention was given to their ringing tone and their color; an unusually large amount of arsenic was added to copper to make the bronze shine like silver.

"If people use materials in different ways in different societies, that tells you something about those people," Lechtman said.

In the case of the Peruvian bridges, the builders relied on a technology well suited to the problem and their resources. The Spanish themselves demonstrated how appropriate the Peruvian technique was.

Ochsendorf, a specialist in early architecture and engineering, said the colonial government tried many times to erect European arch bridges across the canyons, and each attempt ended in fiasco until iron and steel were applied to bridge building. The Peruvians, knowing nothing of the arch or iron metallurgy, instead relied on what they knew best, fibers from cotton, grasses, and saplings, and llama and alpaca wool.

The Inca suspension bridges achieved clear spans of at least 150 feet, probably much greater. This was a longer span than any European masonry bridges at the time. The longest Roman bridge in Spain had a maximum span between supports of 95 feet. And none of these European bridges had to stretch across deep canyons.

The Peruvians apparently invented their fiber bridges independently of outside influences, Ochsendorf said, but these bridges were neither the first of their kind in the world nor the inspiration for the modern suspension bridge like the George Washington and Verrazano-Narrows Bridges in New York and the Golden Gate in San Francisco.

In a recent research paper, Ochsendorf wrote: "The Inca were the only ancient American civilization to develop suspension bridges. Similar bridges existed in other mountainous regions of the world, most notably in the Himalayas and in ancient China, where iron chain suspension bridges existed in the 3rd century B.C."

The first of the modern versions was erected in Britain in the late 18th century, the beginning of the Industrial Revolution. The longest one today connects two islands in Japan, with a span of more than 6,000 feet from tower to supporting tower. These bridges are really "hanging roadways," Ochsendorf said, to provide a fairly level surface for wheeled traffic.

In his authoritative 1984 book, "The Inka Road System," John Hyslop, who was an official of the Institute of Andean Research and associated with the American Museum of Natural History, compiled descriptions of the Inca bridges recorded by early travelers.

Garcilasco de la Vega, in 1604, reported on the cable-making techniques. The fibers, he wrote, were braided into ropes of the length necessary for the bridge. Three of these ropes were woven together to make a larger rope, and three of them were again braided to make a still larger rope, and so on. The thick cables were pulled across the river with small ropes and attached to stone abutments on each side.

http://agutie.homestead.com/files/Quipu_B.htm

Caral: Ancient Peru city reveals 5,000-year-old ‘writing’
July 19, 2005, 22:45, SABC News

Archeologists in Peru have found a “quipu” on the site of the oldest city in the Americas, indicating the device, a sophisticated arrangement of knots and strings used to convey detailed information, was in use thousands of years earlier than previously believed. Previously the oldest known quipus, often associated with the Incas whose vast South American empire was conquered by the Spanish in the 16th century, dated from about 650 AD.

But Ruth Shady, an archeologist leading investigations into the Peruvian coastal city of Caral, said quipus were among a treasure trove of articles discovered at the site, which are about 5,000 years old. “This is the oldest quipu and it shows us that this society ... also had a system of “writing” (which) would continue down the ages until the Inca empire and would last some 4,500 years,” Shady said. She was speaking before the opening in Lima today of an exhibition of the artifacts which shed light on Caral, which she called one of the world’s oldest civilizations.

The quipu with its well-preserved, brown cotton strings wound around thin sticks, was found with a series of offerings including mysterious fiber balls of different sizes wrapped in “nets” and pristine reed baskets. “We are sure it corresponds to the period of Caral because it was found in a public building,” Shady said. “It was an offering placed on a stairway when they decided to bury this and put down a floor to build another structure on top.”

Pyramid-shaped public buildings were being built at Caral, a planned coastal city 180km north of Lima, at the same time that the Saqqara pyramid, the oldest in Egypt, was going up. They were already being revamped when Egypt’s Great Pyramid of Keops (or Khufu) was under construction, Shady said. “Man only began living in an organized way 5,000 years ago in five points of the globe - Mesopotamia (roughly comprising modern Iraq and part of Syria), Egypt, India, China and Peru,” Shady said, adding Caral was 3,200 years older than cities of another ancient American civilization, the Maya.

http://www.cristobalcolondeibiza.com/2eng/2eng15.htm

THE QUIPU KNOTTED STRINGS
In Fusang: Chinos en América antes de Colón, pages 52-55, Gustavo Vargas Martínez brings up an intriguing subject that would seem to point to yet another cultural link of enormous significance in the life of pre-Columbian South America. He says that ‘special mention should be made of the knotted strings, since not only are they an element of analogical confrontation, but basically, they also represent an acquired system that has to be learnt. In his book, Histoire de la Chine the eminent Jesuit Chinese scholar, P. Martin (*) had already remarked on the ancient Chinese system of knotting strings, many years before the appearance of writing. They used to place the knots at specific intervals, make use of different colours and, by carefully following agreed rules, they created a sign code substituting other ways of counting and writing’. What is most astounding, says Vargas, is that ‘an identical system was discovered among the Incas, so sophisticated that it was used as an official register for their annals, State accounts, astronomical observations, rates and taxes and even as a means of communication, since it was used to carry news and message over long distances’. Among the Incas these strings were called quipus, and the Chinese called them qi pui, ‘back memorising’; in China today the same system is known as chie sheng. It is perfectly obvious for anyone to see that the quipu is a forerunner of the abacus (**), in common use all over Asia up to the present day.

http://bbs.cri.cn/simple/index.php?t62259.html

Bamboo Bridges

Some of the earliest of all suspension bridges were ones constructed with cables woven from bamboo strips. Throughout their long history, the Chinese have built suspension bridges to span fast-flowing rivers and deep ravines, and the Incas also designed hanging bamboo bridges as marvelous as those of the Chinese, Janssen notes.

In “China Bridge,” a team of experts brought together by NOVA constructed a suspension bridge using bamboo cables to hang the draping structure. Cabled bamboo strips once held up the great Anlan bridge on the Min River, which historians consider one of the engineering marvels of the ancient world. The bridge hung from bamboo cables from roughly the third century until 1975, when steel cables replaced the bamboo.

granted, quipu are not referred to in this article, but age appears to be established:

http://www.philipcoppens.com/caral.html

Caral is indeed hard to accept. It is very old. Still, its dating of 2627 BC is beyond dispute, based as it is on carbondating reed and woven carrying bags that were found in situ. These bags were used to carry the stones that were used for the construction of the pyramids. The material is an excellent candidate for dating, thus allowing for a high precision.
The town had a population of approximately 3000 people. But there are 17 other sites in the area, allowing for a possible total population of 20,000 people for the Supe valley.
All of these sites in the Supe valley share similarities with Caral. They had small platforms or stone circles. Haas believes that Caral was the focus of this civilisation, which itself was part of an even vaster complex, trading with the coastal communities and the regions further inland – as far as the Amazon, if the depiction of monkeys is any indication.

For an unknown reason, Caral was abandoned rapidly after a period of 500 years (ca. 2100 BC).

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