Otzi

The axe of "Otzi the Iceman (well-preserved mummy dated to 3300 BC) is made from copper. 

The reddish metal was already known in prehistoric times. It occasionally occurs as a native metal, but mostly in conspicuous green ores, from which it is extracted relatively easily. It is convenient to work, but not very hard. Not very optimal as a tool ("Otzi the Iceman" had a copper axe with him). Only through the addition of tin is the more useful bronze obtained. Its zinc alloy is the versatile and widely used brass. Copper is one of the coinage metals. Water pipes are commonly made of copper. Its very good thermal and electrical conductivity is commonly exploited (cable ), as well as its durability (roofs, gutters), as the verdigris (basic copper carbonate) protects the metal. Cu phthalocyanines are the most beautiful blue pigments. Seems to be essential to all life as a trace element. In some molluscs, Cu replaces Fe in the heme complex. A 70-kg human contains 72 mg. 

Approximately 5000 years ago, a man set out to climb the Tyrolean Alps on the Austrian-Italian border. At death, he was between 40 and 50 years old and suffered from several medical ailments. Some scientists believe he was caught in a heavy snowfall, fell asleep, and froze to death. Others suppose he was murdered during his journey. Either way, his body was covered with snow almost immediately and, due to the freezing weather, rapidly became a mummy - The Iceman . In 1991, his body was re-exposed and discovered by climbers in the Otzal Alps, explaining why the Iceman , as he was called, was given the nickname Otzi (or, more commonly, as just Otzi). 

His body (see Figure 8.13) was retrieved and taken to the Department of Forensic Medicine at the University of Innsbruck. Their analytical tests - principally radiocarbon dating - suggest that Otzi died between 3360 and 3100 bc. Additional radiocarbon dating of wooden artifacts found near his body show how the site of his death was used as a mountain pass for millennia before and... 

But how, having defined the half-life h/2 as the time necessary for half of a substance to decay or disappear, can we quantitatively determine the time elapsing since Otzi died In Justification Box 8.4, we show how the half-life and the rate constant of decay k are related according to... 

Worked Example 8.15 A small portion of Otzi s clothing was removed and burnt carefully in pure oxygen. The amount of 14C was found to be 50.93 per cent of the amount expected if the naturally occurring fabric precursors had been freshly picked. How long is it since the crop of flax was picked, i.e. what is its age ... 

The BBC Website has a page dedicated to Otzi the Iceman, with some nice pictures go to http //www.bbc.co.uk/science/horizon/2001/iceman.shtml, which also reproduces the full transcript of an hour-long documentary. 

For a briefer scientific analysis of Otzi, Archeological Chemistry (above) devotes a small case study to Otzi, see its p. 251 ff. And several Websites are devoted to him, including http //info.uibk.ac.at/c/c5/c552/Forschung/Iceman/iceman-en.html and the French site http //www.archeobase.com/v texte/otzi/corp/cor.htm. 

Otzi the Iceman, and some artifacts found around his body (Werner Nosko/EPA/Corbis]... 

Radiocarbon dating reveals when Otzi died, but not how old he was. Forensic anthropologists can approximate the age at death by studying... 

The mummy only weighs about 30 poimds (13 kg) and is about five feet (1.54 m) in length, but because of shrinkage this does not reflect the Iceman s true physique. According to the South Tyrol Museum of Archaeology in Bolzano, Italy, which houses the body, the living Otzi would have been about 63 inches tall (1.6 m) and weighed 110 pounds (50 kg). 

But where did he come from Tie may have been raised in the same region where his body was found, or he might have been a newcomer to the area, or just traveling through. To determine which is the case, chemists and biologists have developed techniques that make use of certain isotopes. As with forensic evidence, these isotopes can be found in Otzi s teeth and bones. 

By examining Otzi s teeth and bones and comparing their isotope ratios to those foimd in the nearby environments, archaeologists can get clues about where the Iceman grew up and where he spent his adulthood. (More precisely, these measurements indicate where Otzi s food and water came from. But in this ancient era, Otzi would have probably obtained most or perhaps all of the necessities of Ufe from the local area.) Teeth enamel provide clues of childhood environment, and bone, which gets remade every decade or two, indicates a more recent abode. 

Paabo and his colleagues took extraordinary precautions in their analyses, comparing their results with controls that did not contain any Iceman samples. The researchers showed that several sequences found in the samples were contaminants, but Otzi s DNA was slightly different and, as expected, more degraded because of age. As an additional control, the researchers performed several experiments in a different laboratory, showing that the DNA they found was not a contaminant contributed by their own equipment. 

Another study of Otzi s DNA is more controversial. In 2003, the archaeologist Tom Loy at the University of Queensland in Australia tested some of the Iceman s equipment, including his knife, arrows, and coat. Loy had noted signs of blood, and when he used PCR on the samples, he found not one individual s DNA, but four. This evidence suggests that... 

Otzi had been in a battle soon before he died, resulting in the blood of several of the combatants staining his clothes and weapons. 

Analyses of food and drink are not limited to the residues of unconsumed substances. In the Iceman s case, scientists had access to the body—and therefore to Otzi s last ingested meals. 

Franco Rollo and his colleagues at the University of Camerino in Italy studied DNA extracted from samples of Otzi s intestinal contents. 

The chemical techniques discussed in this chapter have granted archaeologists an incredible ability to revisit the past. With the aid of chemistry, archaeologists now believe they have a rough idea of Otzi s last days. This knowledge includes the analysis of his meals but goes much further—researchers have used the intestinal contents to track Otzi s final journey. The key component in this study was pollen. 

Pollen consists of reproductive cells released by plants (and sometimes carried by insects) at certain times of the year. Individual species of plant are identifiable by the grains of pollen they generate. Klaus Oeggl of Innsbruck University, James H. Dickson at the University of Glasgow in Scotland, and their colleagues have studied pollen samples obtained from Otzi s digestive tract. Some of this pollen may have been eaten intentionally, but Otzi probably swallowed most of it accidentally, either in the course of eating a meal or by inhalation. 

In 2005, scientists discovered the cause of Otzi s death. A few years earlier, in 2001, Paul Gostner wheeled an X-ray machine to Otzi s chamber in the South Tyrol Museum. Gostner, who works at the Central Hospital in Bolzano, Italy, discovered a stone arrowhead embedded in the back of Iceman s left shoulder. Earlier X-ray scans had missed the small object. The arrow shaft was not in Otzi s body, nor had it been found nearby. The fatality of the wound became evident in 2005, when Central Hospital acquired an X-ray machine with higher resolution. Gostner and other staff members of the hospital brought Otzi in for a scan—it was a rush job, otherwise Otzi s body would quickly decompose. They discovered that the arrowhead had gashed a large and important artery, the subclavian artery, which carries blood to the arm. Such a serious injury would have caused Otzi to bleed to death in minutes. 

One theory, based on the pollen analysis, suggests that when Otzi returned from a trip to higher altitudes, he got into a dispute with some people in the village. According to the isotope evidence coming from the Iceman s bones and teeth, he was familiar with the area, so he would have probably known the villagers—they may have even been relatives. Otzi retreated back into the moimtains after the fight, only to die at the hands of a skilled archer. 

But if this scenario is true, why was Otzi in the mountains in the first place Perhaps the fight occurred earlier, and Otzi fled into the mountains. Then, in accordance with the pollen analysis, he descended briefly, maybe to retrieve some supplies. But this descent may have been his undoing, for he might have been seen and tracked. High in the mountains, where no one would learn of the deed—at least not until 5,300 years later—the killer struck. 

The tales of individuals such as Otzi reveal something about the culture in which they lived. In past times, as in the present, disputes have a way of escalating into extreme violence. Other archaeological chemistry concerns the fate of empires. 

The novel, and subsequent film, offered an exciting story, but one that is unlikely to ever become a reality. DNA degrades, even DNA deposited in locations with little chemical activity. For instance, although parts of Otzi s body were preserved for more than 5,000 years, researchers could not recover any nuclear DNA and foimd only bits and pieces of mitochondrial DNA. Since the dinosaurs became extinct about 65 million years ago, any hope of recovering enough dinosaur DNA to duplicate or reproduce these animals is imreaUstic. 

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