Tales of the dead: everyone has a story to tell. Now, with the help of high-tech tools, even ancient mummies can share their secrets.
Most people would have cringed at the sight. But not Lloyd. The ophthalmologist, who studies the structure and diseases of eyes, excitedly opened the package and carefully took out the orbs.
These were no ordinary eyeballs. The orange and shriveled spheres "resembled Cheez Doodles," says Lloyd. Why? They had been plucked from a mummy of a woman that had been unearthed in the Atacama Desert in northern Chile. The woman was mummified when, roughly 750 years ago, her dead body was buried in the desert. Covered in dry sand, her body dehydrated and turned into a mummy.
Her remains, along with those of other mummies, can teach scientists about ancient people--from their lifestyles to the diseases that struck them. But a mummy's dried-out skin and organs obscure these details. Using modern medical techniques, Lloyd is one of many researchers peering into these shriveled bodies to unlock long-held secrets.
By examining a mummy's eyes, Lloyd hopes to spot evidence about the diseases that affected ancient humans. "The eye doesn't miss much," he says. "In most diseases, there are signs in the eyes."
To examine his mummified samples, Lloyd first had to restore the dried-out organs to their original plump and moist condition. But refilling the eyes with the water lost during mummification takes more than just plopping them in a glass of water. "The rush of fluid into the cells would be so fast that the cells would burst," says Lloyd. Past attempts at rehydrating mummy eyes churned out samples resembling mushy oatmeal.
Lloyd has devised a new method that uses a mix of liquid chemicals instead of water. As the eyeballs soak, the chemicals form a barrier along the outer edge of the cells. This helps limit the number of water molecules that pass through, ensuring that the cells don't burst. After bathing for a few days, "the eyeballs came right back to life," says Lloyd. "They looked like fresh specimens that had just come through the operating room."
Lloyd then carved the eyes into thin sections that he could examine under a microscope. One surprising find: The mummified woman, thought to be 23 years old when she died, had a cataract. This clouding of the eye lens usually occurs in older people. Lloyd suspects that the woman's early eye ailment may have been the result of living at lofty elevations, where her eyes were exposed to high levels of the sun's damaging rays.
Now that Lloyd has learned how to "resurrect" eyeballs, he is waiting for a colleague to mall him more mummified eyes. "We want to look for signs of other diseases such as diabetes and high blood pressure," he says.
Lloyd was able to examine the mummified eyes in detail because in the past, scientists often conducted autopsies of mummies. They would slice open the body, remove each body part, and store the mummy in pieces. Today, however, researchers prefer to preserve the mummy whole.
Instead of mailing body parts across the globe, scientists transport whole mummies to facilities like hospitals where they analyze them with computed tomography (CT) scans. This technique produces detailed 3-D images of a mummy's bones and organs without making a single incision (see diagram, above).
Scientists slip a mummy into the opening of a CT scanner, where a rotating device shoots X-rays at the remains. These high-energy waves pass through the body and hit detectors on the other side of the body. The X-rays easily penetrate the mummy's soft tissues. But higher-density materials such as bones, which have tightly packed atoms of calcium, absorb many of the waves. So by tracking the number of X-rays that hit the detectors, a computer produces images of the different density materials in the body. "A brighter area on the CT image represents a higher density material," says Jonathan Elias, director of the Akhmim Mummy Studies Consortium in Pennsylvania.
During a CT scan, the device rotates around the mummy, scanning successive slices of the body at different angles. A computer "glues" these sections back together to make a complete image of the mummy. "Then we can manipulate the image without ever lifting the mummy again," says Elias.
Several years ago, a CT scan revealed the cause of death of a 5,300-year-old mummy known as "the Iceman." In 1991, climbers found the Iceman, also known as (Otzi (OHT-zee), frozen in a mountain glacier in Italy. The extreme cold of his mountain grave kept hungry microbes at bay. As a result, his body never decayed and he became an ice mummy. An X-ray of the mummified body revealed a stone arrowhead in his shoulder, suggesting that he was killed by a shot in the back.
With additional probing, scientists are finding even more clues about Otzi's life. Christopher Ruff, a biologist at Johns Hopkins University in Maryland, used CT scans to measure the height of Otzi's skeleton and the width of his pelvic bone. By comparing these measurements with the body proportions of modern humans, Ruff estimated that Otzi had a muscular build. At only 1.58 meters (5.2 feet) tall, he weighed roughly 61 kilograms (135 pounds). "He only looks skinny now because he has been dehydrated," says Ruff.
What's more, the CT scans showed that Otzi's shinbone was larger than average. The bone was also bigger from front to back than it was from side to side. A person's leg bones can bulk up like this from frequently walking up and down steep slopes. This finding led Ruff to conclude that Otzi likely worked in the mountains, perhaps herding animals near high mountain passes.
CT scans can also reveal how mummies were preserved. Rather than being naturally mummified in ice or desert sand, most Egyptian mummies were preserved by embalmers. After a person died, these workers would remove the person's internal organs. Then they would cover and fill the body with packets of salt and other chemicals to dry it out before wrapping it in cloth. But studies of mummies have shown that each mummy received slightly different treatment.
The image produced by a CT scan of one ancient mummy discovered in the Egyptian city of Akhmim (AHK-meem) revealed a bright spot beneath the mummy's left arm. This high-density area, which absorbed many of the CT machine's X-rays, is a circular plate wedged in the mummy's linen wrapping. "[Having] it there may signify that the person's death was related to a pain in that region," says Elias. Another mummy he studied "had over 25 [plates] in its wrappings," Elias says.
Elias says he doesn't know the significance of each of the different mummification methods. But he hopes that modern medical techniques will help him solve the mysteries. "We are always looking for new technology to help us learn more about the history of these mummies," he says.
Discover how ancient Egyptians made mummies at: www.ancientegypt.co.uk/mummies/home.html
William Lloyd soaked the mummified eyeballs--along with the orbits that hold them--in chemicals for a day. Once the eyeballs were rehydrated, Lloyd was able to easily identify the oval-shaped lens and the optic nerve (see diagram, right), which transmits images to the brain.
CRACKING THE CASE
Researchers have pored over the mummified remains of Otzi the iceman for 15 years. Until they exposed the dried-out body to X-rays in 2001, scientists suspected that Otzi had died of hypothermia. The resulting images, including detailed computed tomography (CT) scans, revealed that Otzi had been shot with an arrow.
it's your choice
1 How did Lloyd rehydrate mummy eyeballs?
(A) He soaked them in water.
(B) He used a mix of chemicals.
(C) He heated the eyeballs.
(D) He exposed the eyes to X-rays.
2 "The Iceman" became a mummy because
(A) his body decayed very rapidly after he died.
(B) embalmers preserved him.
(C) the cold climate where he died kept decay-causing microbes at bay.
(D) he was buried in a desert.
3 X-rays would most easily penetrate
(A) stone arrowhead.
(B) skin tissue.
(C) arm bone.
(D) leg bone.
HANDS-ON SCIENCE (No Lab Required)
After reading "Tales of the Dead" (p. 16), try this activity.
Which would you expect to dry out the fastest: an apple wrapped in gauze or an unwrapped apple?
* 8, 7-oz plastic cups * marker * 2 apples, each cut into quarters * pan scale * paper and pencil * 250 ml (1 cup) of each: table salt, Epsom salt, baking soda * 4 strips of gauze, each 66 cm (26 in.) long * 4 rubber bands
1 Line up four plastic cups. Use a marker to label each cup as follows: Control Unwrapped, Table Salt Unwrapped, Epsom Salt Unwrapped, Baking Soda Unwrapped.
2 Weigh an apple slice using a pan scale. Record the weight in a data table.
3 Place the weighed apple slice into a cup.
4 Repeat Steps 2 and 3 with three fresh apple slices, putting each one into a separate cup. Each of the four labeled cups should now contain a weighed apple slice.
5 Pour 125 ml (1/2 cup) of each of the following into the corresponding labeled cup: table salt, Epsom salt, and baking soda.
6 Set cups aside, out of direct sunlight.
7 Line up four fresh plastic cups. Use a marker to label each cup as follows: Control Wrapped, Table Salt Wrapped, Epsom Salt Wrapped, Baking Soda Wrapped.
8 Weigh a fresh apple slice. Record the weight.
9 Wrap a 66 cm (26 in.)-long strip of gauze tightly around the apple slice so that it is completely covered.
10 Secure the gauze with a rubber band.
11 Place the wrapped apple slice into a cup.
12 Repeat Steps 8 through 11 with three fresh apple slices, putting each one into a separate cup. All four cups should now contain a wrapped apple slice.
13 Repeat Steps 5 and 6 for the "wrapped" cups.
14 After four days, remove each apple slice from its cup one at a time. Shake off as much salt or baking soda as possible, and unwrap each wrapped apple. Weigh each apple slice and record its weight.
15 Calculate the amount of water lost from each apple slice. Hint: Subtract each slice's final weight from its initial weight.
1 Which unwrapped apple lost the most water? Which wrapped apple lost the most water?
2 Embalmers wait for a body to dry out before wrapping it into a mummy. Why might this be?
PHYSICAL: Technology and Chemistry
Tales of the Dead
Jump-start your lesson with these pre-reading questions:
* The human eyeball measures approximately 2.5 centimeters (1 inch) in diameter. Suppose you're a scientist and you receive a shriveled-up eyeball, dried out from spending 750 years buried under hot desert sand. How might you bring the eyeball back to the size of when its owner was still alive?
* How would you describe the appearance of a mummy? What do these characteristics tell you about where the mummies come from and how they formed?
* Today, scientists learn about the diseases that affect humans by examining the human body. They may analyze samples of living tissue and cells, study blood samples, and evaluate symptoms that a patient experiences, among other procedures. What might be some challenges in learning about diseases from a mummy?
* Scientists are learning about ancient people and societies by removing mummies from their tombs and examining the remains. Some people think that disturbing the mummies is disrespectful to the dead. Should scientists continue to search for and open ancient tombs? Explain your reasoning.
HISTORY: Around 2500 B.C. in ancient Egypt, embalmers began turning human remains into mummies. Do research to learn about ancient Egyptian society. Then, create a poster that describes the culture and beliefs that led ancient Egyptians to create mummies.
* For more on how modern science investigates ancient mummies, read "The Case of the Mummified Cowboy," by Mona Chiang, Science World, November 17, 2003.
* There are many different types of mummies from around the world. Learn about them at this BBC Web site: www.bbc.co.uk/history/ancient/egyptians/mummies_01.shtm/
* This Web site from the Smithsonian Institution explains how ancient embalmers preserved mummies: www.si.edulresourcelfaq/nmnh/mummies.htm
* Students can learn more about Egyptian mummies at this kid-friendly site from the University of Michigan: www.si.umich.edu/chico/mummy/
CHECK FOR UNDERSTANDING
DIRECTIONS: Fill in the blanks to complete the following sentences.
1. A(n) -- is a scientist who studies the structure and diseases of eyes. This specialist often treats older people suffering from --, a clouding of the eye lens.
2. Scientists use -- (CT) scans to produce three-dimensional images of a mummy's insides. The scans use high-energy -- to penetrate the mummy's skin and organs.
3. "The Iceman" became a mummy because extreme cold kept -- from eating his body. Result: His body never --.
4. To make an Egyptian mummy, -- started by removing most of a dead person's --.
Tales of the Dead
1. ophthalmologist; cataracts
2. computed tomography; X-rays
3. microbes; decayed
4. embalmers, internal organs
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|Article Type:||Cover story|
|Date:||Oct 23, 2006|
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