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Remnants of the Past

High-tech analyses of ancient textiles yield clues to cultures

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11:18am, December 5, 2004
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In a museum lab, Irene Good is studying pieces of silk from long-lost cloth found at archaeological sites in western Europe and central and south Asia. The material at hand—short lengths of threads that were spun from the cocoons of moths—is barely visible. Good immerses the threads in a solution to tease apart the strands of protein. Then, she uses several methods of biochemical analysis to examine the proteins' amino acids. What amino acids are present and their order vary for proteins from different species of moths and therefore give a clue to the place where the silk was made.

"What I love most is being able, not just to alter what's known, but to improve access to the past based on very tiny pieces of evidence," Good says.

"Until recently, it was assumed that all [ancient] silk was from China," says Good, a specialist in fiber analysis and ancient-textile production and trade at Harvard University's Peabody Museum. Scholars held that silk dating from 2400 to 700 B.C. was carried afar on trade routes from China.

But Good's work is now calling that assumption into question. Her findings indicate that the ancient silk came not from domesticated Chinese silkworms but from species of wild moths native to western Europe and Asia.

"Now, it looks like some of the early silk industry outside China was earlier than thought and more widespread," Good says.

Today, Good and other researchers are applying high-tech methods of chemical analysis to ancient textiles and fibers to glean unique clues about past civilizations. The results are shedding light on many aspects of daily life among early peoples, such as their technological skills and funeral customs.

Much of the insight is coming from minuscule samples of textiles, which archaeologists categorize as "fiber perishables." Until recently, these remains were usually overlooked because they were frayed, discolored, or too fragile to withstand the rigors of analysis.

"Because textiles are organic, they're subject to biological deterioration from air, water, minerals, insects, and fungi. All kinds of things attack organic material and use it as their dinner," says Joseph Lambert of Northwestern University in Evanston, Ill. He is a pioneer in the use of analytical-chemical techniques for the study of archaeological materials.

Most cloth and other fiber goods degrade over time and eventually disappear. In some cases, however, ancient textiles survived well because they'd spent centuries in arid, freezing, or low-oxygen environments, such as well-sealed tombs.

Scientific interest in ancient textiles and other fiber objects is burgeoning. "Today, we're finally combining archaeological background with training in [scientific] instrumentation to put it all together," says Lambert.

Scraps of evidence

Chemical analysis and powerful microscopy can reveal remarkable characteristics of textiles: what plants and animals the fibers came from, how the yarns were made, what weaving techniques were employed, and what dyes or pigments were used to color them.

Such information, combined with other evidence, enables researchers to infer the technological skills of early peoples and the cultural importance of their textiles, notes Kathryn Jakes of Ohio State University in Columbus. "People had a particular intent when they were producing these textiles," she notes.

Jakes, trained in polymer chemistry, has used advanced methods of chemical analysis in her 2 decades of research on textiles of early Native Americans in central and eastern North America.

These groups, known collectively as the Hopewell and Mississippi civilizations, inhabited the region extending from Florida to New York and westward to Wisconsin. They lasted from about 100 B.C. until encroachment by European explorers and settlers in the early 1500s. Individual groups had distinctive ways of life, but they shared many beliefs and practices, including elaborate cremation ceremonies in which textiles played an important role.

Among the fabric samples Jakes has analyzed are carbonized scraps from Hopewell burial sites, which were typically earth mounds. Charring during the cremation inhibited the growth of bacteria among the threads and prevented total disintegration of the remnants, she notes.

Jakes has found that textile patterns and structures varied among Hopewell groups. "Although cremation rituals and burials may have been culturally dictated over a wide geographic area, the textiles used in these rituals were locally produced," she notes.

Analyses have revealed decorative patterns indicating that at least some of the now-faded Hopewell-era textiles had been colored. "The presence of color reflects a significant level of technology, including knowledge of colorants in nature and of methods required to affix them to organic materials," says Jakes.

She and her colleagues Amanda Thompson and Christel Baldia have conducted experiments to find out what combinations of plants and minerals the Hopewell groups may have used to produce various colors.

Prehistoric people probably used sumac and bedstraw as dyes, Jakes says, because caches of those seeds have been recovered from archaeological sites although the plants have no known dietary use. In one set of experiments, for example, the researchers made dye baths from sumac berries and bedstraw roots combined with different mineral fixatives. When the researchers tested the baths on fibers from milkweed plants and rabbit hair, only one combination—sumac, bedstraw, and potassium carbonate—produced a deep red that was colorfast.

To estimate the time and skill that early Native Americans may have needed to make textiles, Jakes and her colleagues have done studies replicating yarn production from different plant fibers. In one experiment, several spinners were asked to produce yarns comparable in quality to those of textile artifacts from a Mississippian-period site in Carter County, Ga. The results demonstrated that a spindle technique was more than twice as efficient as hand-spinning methods. The spinning of cotton fibers went much slower than that of flax or hemp because cotton fibers are short and require more twists per turn to hold together the fibers.

These findings and others indicate that the early natives of what is now the eastern United States were highly skilled at cloth making, says Jakes, who presented some of her findings last August in Philadelphia at a meeting of the American Chemical Society.

Threads bare all

Many modern techniques of analytical chemistry are well suited to the study of ancient textiles because they require only small samples of material, Lambert notes. These techniques also enable researchers to investigate other organic materials that may have come in contact with textiles.

Several years ago, James Adovasio and David Hyland of Mercyhurst College in Erie, Pa., analyzed trace residues of blood and other animal tissue on textile remnants found at a prehistoric Indian cemetery in Windover, Fla. To compare these residues with samples of deer and human tissue, the researchers used a technique that relies on antibodies to identify proteins. The results, Adovasio says, indicated that some of the human remains had been wrapped in deer hide as well as textiles.

Richard Evershed of the University of Bristol in England is another pioneer in the chemical analysis of organic archaeological materials. In the Sept. 16 Nature, he and his colleagues describe their study of cloth wrappings from animal mummies of ancient Egypt. The Egyptians preserved millions of mammals, birds, and reptiles as votive offerings. Scholars had assumed that ancient people used relatively simple and inexpensive methods to prepare this multitude of animals for burial.

Evershed's findings call that assumption into question. His team combined mass spectrometry with gas chromatography to analyze samples from cat, hawk, and ibis mummies. The embalming substances turned out to include fairly exotic materials, such as oils, beeswax, sugar gum, and tree resins, and were as complex as those used for human mummification. Evershed suggests that the ancient Egyptians had surprisingly sophisticated knowledge of how to use various preservatives.

Dream weavers

The study of ancient textiles and other organic materials is a much-needed counterpoint to the traditional archaeological focus on objects made of stone, bone, metal, and clay, says Penelope Drooker of the New York State Museum in Albany. Evidence from tools and weapons can lead to skewed interpretations of past life, she says.

Until fairly recently in human history, Drooker points out, perishable goods comprised a large part of the materials of everyday life. At some archaeological sites in western North America, for example, an estimated 95 percent of recovered artifacts were made of wood, bark, plant fiber, leather, fur, or feathers.

"It takes a conscious effort to reconstruct the richness of traditional material culture," says Drooker, a specialist in fiber-based archaeological objects found in the eastern United States. "Therefore, it is very important for archaeologists to pay attention to the fragments of perishable material culture that do survive."

Much of Drooker's research has focused on impressions of ancient textiles left in clay and other once-malleable substances. She is currently studying what appear to be markings of fine textiles etched in stone palettes recovered from prehistoric burial mounds. Native Americans may have used the palettes to prepare pigment for various rituals, says Drooker.

As sophisticated techniques of analysis have revealed more-detailed information about ancient textiles, scholars have been rethinking ideas about the early development of skills such as spinning and weaving. Fiber samples found in caves in France had convinced scientists that textile production first arose about 15,000 years ago. Now, some scholars assert that weaving and cloth making developed considerably earlier.

After examining early representations of human clothing, Elizabeth Barber of Occidental College in Los Angeles concluded that textile weaving is at least 20,000 years ago. A specialist in the Bronze Age and Neolithic cultures of the Aegean and southeast Europe, she has argued that fiber-making expertise was as revolutionary as the creation of stone and metal tools.

Learning to twist plant and animal fibers into stringlike yarns enabled prehistoric people to weave nets, baskets, and other objects that eased the chores of everyday life, Barber explains in her extensive writings. As the tasks of providing food, clothing, and shelter were divided between men and women in tribal societies, she says, women became the primary weavers because they could perform that activity while tending children.

Research by Adovasio and Olga Soffer of the University of Illinois at Urbana-Champaign suggests even older origins for the emergence of weaving skills. When these researchers analyzed impressions in clay artifacts from the Czech Republic, some dating from 28,000 years ago, they concluded that the materials bore the markings of cloth, nets, and baskets. Adovasio and Soffer contend that ancient carved "Venus" figurines from central and eastern Europe are depicted wearing woven caps, skirts, and head coverings—evidence, they say, of sophisticated weaving skills among Ice Age people (SN: 10/21/00, p. 261: Available to subscribers at Stone Age statuettes don disputed apparel). Other scholars disagree.

Adovasio, who has built an elaborate lab at Mercyhurst for the study of archaeological artifacts, continues seeking new ways to apply modern scientific tools to cloth remnants and other objects from past cultures.

"There's no practical end to what you can use modern analytical technology for," he says, "as long as you frame the research in such a way that the technology can help you answer the question."

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