Ötzi the Iceman Reveals 5,300-Year-Old Secrets

by Cynthia Washam

For more than 30 years, scientists from around the world have flocked to a museum in the Italian Alps to learn from a 5,300-year-old man. He’s known as Ötzi the Iceman, nicknamed for the nearby Ötzal Alps, where he was found in 1991. 

The 5-foot, 2-inch 110-pound corpse is a mummy, preserved essentially as he looked the day he died. Unlike Ancient Egyptian mummies—eviscerated, salt-dried, linen-stuffed, and coated with resin—Ötzi freeze-dried naturally in the lofty Alps. 

His body was so well-preserved that the two hikers who found his upper torso poking out of a shallow gully in an ice field assumed he was a recent victim of a mountaineering accident. Radiocarbon dating of his tissues several days later showed that he died around 3250 BCE (Before the Common Era), making him the oldest naturally mummified human ever found. A bone analysis indicates he was about 45 when he died—a ripe, old age for his time.

Archaeologist Konrad Spindler estimated from the tools found with the mummified Iceman that he was 4,000 years old. A short time later, radiocarbon dating proved that Spindler’s estimate was off by more than 1,000 years. 

Ötzi’s remains suddenly gave scientists a chance to peer into life during the Copper Age, which lasted from about 3500 BCE to 2200 BCE. It takes its name from copper smelting, which was increasingly used during the Copper Age to make tools that had been previously made from stone. It was a time when people lived in stone houses, cultivated wheat and barley and raised livestock, including sheep and goats. People supplemented their diets with the wild game they hunted. 

Despite having nothing more than his remains, scraps of his clothing and an assortment of tools, scientists determined how Ötzi died, what he ate for his last meals and even what diseases he had (he probably never knew). Thanks to a daring experiment, they even learned how he probably got the 61 tattoos scattered around his body.

“I’m grateful his remains have been conscientiously preserved,” says Dr. Nina Jablonski, an anthropologist at The Pennsylvania State University in State College, Pennsylvania, who specializes in the evolution of human skin color. “It gives us a window into how the past looked.”

Although amateur archaeologists can’t examine Ötzi like scientists can, they can view his remains at the South Tyrol Museum of Archaeology in Bolzano, Italy, where he’s kept frozen. Visitors can also check out his bearskin hat and tools, as well as a life-size replica of him, decked out in replicas of the leather and fur clothes Ötzi was wearing at the time of his death.

Shifting Theories

Like a good mystery novel, the Iceman disclosed the secrets of his past bit by bit. Spindler was the first to glimpse Ötzi’s past when he examined the mummy shortly after its removal from the ice field. Spindler is an archaeologist, a scientist who studies ancient artifacts and ruins to better understand bygone cultures. When he saw the copper-bladed ax and flint dagger found alongside the Iceman, he understood that Ötzi was no modern-day mountaineer. In the days after Ötzi’s discovery, more artifacts were recovered near his burial site, some 3,210 meters (10,500 feet) above sea level. They included 14 arrows, an unfinished bow, a leather pouch, a wooden backpack frame, and pieces of clothing. 

Spindler described what seemed to be a plausible scenario of Ötzi’s death. Because some arrows were broken and the bow was unfinished, he assumed Ötzi had been involved in a scuffle that had caused him to flee from the valley below. Spindler suggested he had lain exhausted in the gully where he froze to death. 

The Iceman’s discovery drew researchers from a variety of disciplines, all eager to uncover his secrets. One of the biggest stories emerged in 2001 when a 13-millimeter-long arrowhead was found between Ötzi’s rib cage and left shoulder blade. Earlier researchers missed the arrowhead because the shaft had been broken off, presumably by the assailant. The surprise finding came from an X-ray exam. 

Scientists then took a closer look at the Iceman’s back, where they spotted an unhealed wound where the arrow had entered. A more sophisticated computed tomography (CT) scan later indicated the arrow had torn Ötzi’s subclavian artery, which would have caused him to quickly bleed to death. Chemical evidence supporting this finding included the presence of the protein fibrin, a clotting agent, in the red blood cells surrounding the wound. Fibrin appears rapidly at a wound site but disappears very quickly. That it was still present indicates Ötzi did not survive the injury. 

These discoveries upended Spindler’s theory of a freezing death but supported his presumption of a conflict. Further evidence of a fight came from a knife wound found later on Ötzi’s hand. “It was most likely two or three days old (when he died),” says Frank Maixner, a molecular biologist at the EURAC Institute for Mummy Studies in Bolzano, Italy.

DNA Analysis Key to Last Moments

Researchers are inspired by Ötzi and continually add to his story. X-rays, for example, surprised archaeologists by revealing something odd about his stomach. They previously assumed it had dehydrated to the point of becoming invisible, never realizing they were looking in the wrong place. “Ice pushed his stomach under his rib cage,” says Robert Moritz, a protein scientist from the Institute for Systems Biology in Seattle, Washington. The discovery enabled Moritz and his colleagues to delve deeper into Ötzi’s life by examining his stomach contents. 

They found cells that looked like meat and others that looked like plant matter. “I said, ‘Let’s look at the genome of what he was eating,’” Moritz recalls. A genome is the set of DNA instructions found in a cell. Because every species has a unique genome, DNA analysis can identify species from a minute amount of tissue. “[Using DNA analysis] we could pinpoint the species he’d eaten—ibex (a wild mountain goat) and deer,” Moritz says. 

An unexpected finding was the genome for Helicobacter pylori (H. pylori), a common bacterium that can cause stomach ulcers and gastric cancer. Ötzi is the oldest known person infected with H. pylori. While most infected people have no symptoms, Moritz and his colleagues found proteins involved in the inflammatory response to infection.

Another piece of the Ötzi puzzle revealed by DNA is where he went during the last 33 or so hours of his life. DNA analysis of the contents of his intestines identified grains, more game and traces of charcoal, indicating Ötzi probably cooked his meat. A whipworm infestation was also found in Ötzi’s stomach contents. These parasites can cause frequent, painful and sometimes bloody bowel movements.

The most telling find, however, was not the food nor the parasites, but the pollen and spores. These airborne reproductive plant cells apparently drifted onto his last meals. Their location in Ötzi’s intestine indicates the timeline of his last journey. 

Pine pollen far along his digestive tract suggests he ate his first meal just below the timberline. Spores and pollen from other plants suggest he then descended to a warmer zone before climbing again, this time to the treeless, ice-covered area where he was found. “He changed altitude rapidly,” Maixner says, imagining Ötzi was on the run for his life. 

Geneticists also used DNA analysis to study Ötzi’s ancestry and physical traits. Their first effort in 2012 revealed close genetic ties to present-day inhabitants of the Italian island of Sardinia. The mannequin of Ötzi in the Bolzano Museum could pass for a Sardinian, with fair skin and graying, shoulder-length hair. But more advanced analysis a decade later indicated that the first sample had been contaminated with modern DNA, most likely from someone who handled the tissue sample. The newer study links Ötzi’s ancestry to farmers in ancient Anatolia, a peninsula in the Asian side of Turkey. The updated analysis also revealed a genetic tendency toward baldness and bronze skin. Archeologists at the time the mannequin was made assumed freeze-drying had darkened the corpse’s skin. “It’s far more likely that he would have had excellent tanning ability,” Jablonski says. “He would have had weathered skin. He wasn’t a young man.” 

DNA analysis revealed yet another surprise: Ötzi had the genome for Borrelia burgdorferi, a bacterium that causes Lyme disease. The first known modern cases surfaced in the early 1970s, when several residents of Lyme, Connecticut, developed perplexing symptoms including swollen joints, rashes, headaches and chronic fatigue. In 1981, scientist Willy Burgdorfer connected the symptoms to tick bites and named the bacterium after himself. Ötzi is, by far, the earliest known human infected.

DNA Sequencing

DNA analysis has revolutionized forensic science, and new technology has driven down the cost to the point where pet owners have their dogs’ DNA sequenced. DNA sequencing is the order of the four nitrogenous bases that make up our DNA molecules: adenine (A), cytosine (C), guanine (G) and thymine (T). These bases pair with complementary bases to make up double-helix DNA: A always pairs with T, and G always pairs with C.

 

 

The first step in DNA analysis is to make a lot of it so it can be analyzed easily. To do this, scientists must separate the two strands of double-stranded DNA and then reproduce each strand. They do this using a polymerase chain reaction (PCR). First, nucleic acid denaturation—a high-temperature reaction—is used to separate the two strands. Then the sample is cooled, and complementary sequences of DNA (primers) are introduced. These strands are then used as templates for DNA polymerase—an enzyme that assembles a new DNA strand from free nucleotides.

 

Credit: Kelsey Casselbury
 

The second step is sequencing the DNA. One commonly used method is Sanger Sequencing. In this method, special modified nucleotides—dideoxyribonucleotides (dNTPs and ddNTPs)—are added during the PCR reaction to cut the DNA molecule into smaller and smaller pieces. These modified nucleotides also contain dyes that are specific to the DNA base to which they attach themselves.

At the end of the PCR reaction, the chain terminated  (shortened) DNA fragments are separated by size via gel electrophoresis. Gel electrophoresis is done using electricity to move the DNA, which is negatively charged, through the gel. The speed at which each fragment moves through the gel is determined only by the size of the fragment.

 

Credit: Kelsey Casselbury
 

The last step is to analyze the gel and determine the base pair sequence. Laser excitation of the dyes attached to the modified nucleotides, in combination with the size of the fragments, allows computers and scientists to determine the sequence of the DNA. 

Specific DNA sequences are attributed to different species. Human DNA is 99.9% the same for every human being. 

Credit: Kelsey Casselbury
 

The last step is to analyze the gel and determine the base pair sequence. Laser excitation of the dyes attached to the modified nucleotides, in combination with the size of the fragments, allows computers and scientists to determine the sequence of the DNA. 

Specific DNA sequences are attributed to different species. Human DNA is 99.9% the same for every human being. 

Ancient Ink

We may think tattoos are a modern invention, but Ötzi is the oldest known record of tattooed human remains. “We learned from him that tattooing as a form of decoration or medical treatment existed 5,300 years ago,” Jablonski says. “That’s pretty amazing.”

His tattoos attracted interest for their odd designs as well as their age. All are simple images such as crosses, arrows and sets of parallel lines. Many appear on body areas that would be covered by clothing. Scientists also noted tattoos on other joints that X-rays showed were arthritic. Still others, Jablonski says, “are on main acupuncture meridians. They may have been used to treat pain.”

Lasting Legacy

The Iceman’s most enduring legacy may be glacial archaeology, a branch of science inspired by his discovery. Glacial archaeologists use their knowledge of glaciers to find and study artifacts frozen in ice. Without their expertise, people might still believe Ötzi had been encapsulated in ice from shortly after his death until the time he was found. 

To glacial archaeologists, that theory sounded odd. They knew summer melts were not uncommon, even in the high Alps—so they tested the idea of earlier melts by radiocarbon dating moss, grass and leaves frozen in the gully where the Iceman was found. If Ötzi had been sealed in ice from the time of his death, then the vegetation in the gully would have been at least as old as he was. Radiocarbon dating, however, revealed that the materials were added over a period of many years, suggesting the ice repeatedly melted and refroze.

Since Ötzi’s discovery, mummified remains and artifacts have been exposed by melting ice in Norway and in Canada’s Yukon, along with the Alps. As climate change diminishes glacial ice, scientists expect to find still more prehistoric remains.  

Archaeologist Andreas Putzer, the conservator of the South Tyrol Museum of Archaeology who oversees Ötzi’s preservation, spends his summers searching for remnants of villages where Ötzi and his contemporaries might have lived. He climbs high to get the broadest view. Then he looks for areas that are fairly flat, close to water and wood, and protected from avalanches and rockslides. “If Ötzi wasn’t discovered in 1991, we wouldn’t be here,” he says. “This opened the minds of archaeologists.”