Ötzi – a new understanding of the holy grail of glacial archaeology

Ötzi the iceman is the holy grail of glacial archaeology, nothing less. The discovery of the 5300-year-old mummified body and the associated artefacts created a media frenzy and great public interest. Today, 250000 people visit the Ötzi Museum in Bolzano each year to get a glimpse of Ötzi and the exhibited artefacts. A wealth of scientific papers, popular books and documentaries have been published.

Ötzi was discovered in 1991 in a gully at the Tisenjoch pass close to the Italian/Austrian border. The original interpretation by the Innsbruck-based archaeologist Konrad Spindler was that Ötzi froze to death in the gully. He was quickly covered by a glacier and remained encased in ice until he melted out in 1991. How else could the body and artefacts be so well preserved?

Ötzi findspot
Ötzi findspot (in red) in the Tisenjoch. Source

In many ways, Ötzi was a surprising and odd find when he was discovered. Even though finds from the ice had been recovered in Norway decades before Ötzi’s discovery, this was not well known in the outer world. Thus, when Ötzi appeared, he was a bolt from the blue for the Austrian and Italian archaeological milieu. From the start, it was believed that he was a unique find, preserved by miraculous circumstances. Otherwise, there would surely have been more such finds. It was six years before the first mass melt-out of archaeological finds from the ice in Yukon in 1997 and a few years later in the Alps and Norway (more on the history of glacial archaeology here).

When the first examples of a new type of find are discovered, they will sometimes appear surprising and odd. As time passes and more finds are made, this situation normally changes. The earliest finds no longer appear peculiar, but fit a pattern that was not visible initially. We have seen the same thing happening during our glacial archaeology work here in Innlandet County, Norway. Finds that initially appeared odd and hard to understand, turned out to fit a pattern not visible to us, when we first started out.

Since Ötzi was found in 1991, glacial archaeology has developed as a new archaeological discipline, with its own methodology and a deeper understanding of the complexity of ice sites. There are now hundreds of sites and thousands of finds. However, Ötzi is not becoming part of the pattern. He is still an odd find. Similar very old finds sealed beneath moving glaciers are unknown. The time has come to ask the question: does the original Ötzi story still hold up?

We start at the very beginning.

The discovery and subsequent excavation

Ötzi was discovered by the German couple Helmut and Erika Simon, on Thursday September 19 1991. His upper body was protruding out of the ice in a gully at 3200 m in the Tisenjoch pass on the Italian side of the Italian/Austrian border.

The first picture of Ötzi as he emerged from the melting ice
The first picture of Ötzi as he emerged from the melting ice, taken by the finders – the German couple Helmut and Erika Simon.

The recovery of the body

The Simons reported their find to Markus Pirpamer, the owner of a local mountain cabin, the Similaunhütte on the Italian side of the border. He informed the authorities, both on the Austrian and the Italian side. It was initially not clear whether the find had been made on Austrian or Italian soil. Bad weather delayed the recovery of the body until Monday September 23.

The great age and importance of the find was not immediately understood by the authorities. Ötzi was not the only body to melt out of the ice in the Alps in 1991. It had been a very warm summer, and several other and more recent bodies had melted out of the ice as well. Focus was on recovering the body, which is normal procedure, when the dead are returned by the glacial ice. A number of people visited the site to see the body, before it was recovered. They stepped on the fragile objects and removed artefacts before their locations were noted. This was very unfortunate and led to the destruction of important evidence on the site.

When the Innsbruck-based archaeologist Konrad Spindler saw the copper axe found with Ötzi, he immediately understood that this was not a recent glacier body, but that it had to be at least 4000 years old. The ice mummy became an immediate sensation.

Reinhold Messner (right) looking at Ötzi
Reinhold Messner (right) looking at Ötzi after more ice had melted or been hacked away. Notice the wooden stick in his companion’s right hand. It was used during the first attempts to hack Ötzi out of the ice. It is in fact part of the frame for Ötzi’s backpack. In the upper right corner, we can see Ötzi’s bow resting against the rock. Source

The excavation of the find spot

The find spot was investigated by archaeologists shortly after the find was made, but the appalling weather conditions and the onset of winter quickly stopped the fieldwork. A well-organized and thorough excavation of the gully was conducted in in 1992. A few more artefacts and a number of fragments were recovered, and a large number of samples were collected.

The 1992 excavation
The 1992 excavation of the gully where Ötzi was found. The person to the left has his green boot on the stone on which the body of Ötzi was partly resting. The bow was found just below the sitting person with clutched hands. The quiver was found to the right in the picture, above the black piece of technical equipment. Source

A painstaking reconstruction of where the artefacts were found was also undertaken, based on interviews with people who had been at the site prior to the first proper investigation. It appeared that many of the larger artefacts, not directly associated with Ötzi’s body, were found resting on the stones along the sides of the gully or in a thin layer of dirty ice at the bottom of the gully. Thus, the natural conclusion was that the gully had been free of ice and snow when Ötzi died. However, it was puzzling that artefacts were found at some distance from the body, such as the quiver, which was found 7 m away.

A transect of the find spot. Layer c is a “dirty” ice layer, which incorporated the finds. Source

The Ötzi story

Together with two colleagues, the archaeologist Konrad Spindler in Innsbruck took charge of the investigations, with the collaboration of a number of colleagues from Austria, Italy and other countries. Ötzi has been studied using state of the art methods. Remarkable results concerning his death, his life and his times have been published.

Spindler’s original interpretation

The original interpretation by Spindler (also known as the disaster theory) was first presented at a 1994 conference on Ötzi and published a short time later in his book: Der Mann im Eis (The Man in the Ice). Spindler believed that Ötzi was fleeing across the mountains from the south in the late summer or fall.  Some of his equipment had been damaged in a violent encounter, and he had no time to repair it. He was in pain from broken ribs. Ötzi died in a snow-free gully near the pass. Exposed on the surface, he freeze-dried, which led to the exceptional preservation of his body. A short time later, a glacier covered the area, and buried the body and the artifacts for more than five millennia, like in a time capsule. Ötzi and his artefacts were protected by the gully, so that the moving glacier did not crush them.

Spindler’s interpretation of the find was not unanimously accepted by his colleagues at the time. However, the attractiveness of the story has made it the official Ötzi story to this day. The only point on which there is any public debate now is the question of Ötzi’s cause of death. The 2003 discovery of an arrowhead embedded in his shoulder, and later evidence of a possible trauma to the head, has turned Ötzi from a victim of hypothermia into a murder victim.

More importantly in our context, however, is the work of the eminent botanist Klaus Oeggl, based in Innsbruck, who has published a number of scientific papers based on samples taken from Ötzi himself and during the 1992 excavation. Starting in 1998, Oeggl has shed new light on the time of year for Ötzi’s death, on his death in the gully, and on his subsequent permanent burial beneath the ice, as claimed by Spindler.

Spindler’s story is still alive

I visited the Ötzi museum in Bolzano in 2016, when the 2016 world conference of frozen archaeology was held in Innsbruck. As glacial archaeologists, we were kindly treated to a guided tour of the museum and told the story of the find and the scientific results. The official story presented by the guide was the original Spindler story told above, where a string of lucky coincidences led to the preservation and subsequent discovery of Ötzi. On the homepage of the Ötzi Museum, it says explicitly: “The corpse lay in a 3-by-7-metre-wide gully and was thus protected from the destructive forces of the moving glacier. The rocky gully was probably free of ice when Ötzi died there. Subsequently, he must have been covered by snow and the glacier ice.” “The Glacier Mummy“, an excellent and very nicely illustrated book on the Ötzi find published by and sold at the museum, tells the same story.

The question of time and place of death

Spindler’s interpretation of the find was that Ötzi died in the gully where he was found. Time of death was believed to be in the late summer or fall. The basis for this conclusion was that a sloe was found near the ice mummy, and sloes ripen in late summer. There were also minute pieces of grain stuck in Ötzi’s clothing, and it was believed that they ended up there during threshing.

Doubts arise

The 1992 excavators of the site pointed in their 1995 report to the possibility that the mummy and the finds had been displaced by recurrent thaw and re-freezing processes. An important piece of independent evidence that this might be the case appeared in 1998. Klaus Oeggl had found pollen of hop hornbeam in a sample from Ötzi’s gut. These pollens are produced in March and April in the valley, where Ötzi came from. This time of year may be spring in the valley, but at 3200 m where he died, this is still winter. Even considering the windswept ridge where the find lay, the gully would very likely have been covered in snow, perhaps deep snow. How could he have died down in the gully then?

In 2010, Spindler’s disaster theory was challenged by a group of Italian researchers. They claimed that Ötzi had died in the valley in the spring, been mummified by smoking, and transported to the site in the autumn. According to the researchers, Ötzi was buried on a stone-platform near the later find-spot. They also believed that the mummy and the finds had been moved by recurrent thaw and re-freezing processes. The original Ötzi research group had no problems showing that this hypothesis just did not fit the empirical facts obtained from the investigation of the site. However, the discussion again drew attention to the uncertainties associated with the natural processes on the site.

Map of the findspot
Map of the findspot. Source

The broken equipment

So, Ötzi died in the spring, not in the fall, and natural processes had affected the mummy and the finds. This takes us to the next curious aspect of the find – the broken equipment.

Some of the artefacts found with Ötzi were broken (such as the quiver and the backpack), and pieces were missing. The explanation given by Spindler was that they were broken during a conflict or during Ötzi’s flight for the mountains, and he had no time to repair them.

However, there may be a simpler and more natural explanation for the broken equipment and missing pieces. We learned from a careful analysis of our Lendbreen site is that there are a number of natural processes that affect artefacts lost on the surface of snow and ice. The simple version is that the artefacts may displace from the original place of deposition, they may break into pieces and the broken pieces may scatter. Often artefacts go through all three processes.

The snow and ice cover will melt away during very warm summers, and some of the artefacts originally lost on the ice and snow will melt into hollows below. Such hollows are more protected from the elements and are more likely to preserve snow and ice over the summer, i.e. they are good for artefact preservation. Artefacts that do not make it into such hollows are more likely to be lost over time, as they are more exposed. The exposed artefacts gradually disappear, with wood and birch bark being the last materials to preserve. This pattern can be seen very clearly in the artefact distribution maps at Lendbreen. Pieces of wood and birch bark surround the edges of a large hollow with more favorable preservation conditions, where textiles, leather and horse dung are preserved. Wood and birch bark are very durable, probably because they go through a natural conservation process of freeze-drying due to the cold and dry environment.

Viking Age arrow
Viking Age arrow, with the shaft broken by the pressure from snow and ice. Photo: secretsoftheice.com

When the ice melts completely, the artefacts end up resting on the rock and stones below. This is not because they were originally lost there when there was no ice, but because the layer of ice and snow in-between melted away at some point. During this process, meltwater and strong wind may disperse the artefacts. Once resting on the rocks, the artefacts may break into pieces, due to ice and snow pressure or trampling by animals. After breaking into pieces, the individual fragments may be displaced by meltwater or strong winds. At Lendbreen, we have found fragments of the same artefact hundreds of meters apart. Many of the artefacts have parts missing. That does not mean that people brought these items into mountains in an already broken state. They were broken by natural processes on the site.

Ötzi and the state of his artefacts fits this general process well. The dispersed and broken equipment with missing pieces is likely to be a result of natural processes on the find spot, not a hasty flight. Ötzi died on the surface of the snow. When the snow and ice melted, his body and most parts of his equipment ended up a gully underneath. The missing small parts never made it into the gully, probably because they were displaced by meltwater and wind. Once melted down on to the bare terrain below, and snow and ice recovered the site.

Are there any traces of the artefacts that did not make it into the gully? Remarkably, there is, even though the excavation in 1992 did not extend outside the gully. In 1995, Norwegian scientist Thorstein Sjøvold visited the find spot. He found very poorly preserved remains of a birch bark vessel underneath a stone just south of the gully, outside the excavated area. These remains turned out to be part of a better-preserved birch bark vessel recovered in the gully. The find is in complete accordance with the Lendbreen find circumstances. This piece did not make it into the gully, perhaps together with other artefacts and fragments of less durable materials, now lost. It only survived because it was lying beneath a protecting stone.

Ötzi’s death and broken equipment

A conclusion in line with the evidence and in support of Oeggl’s work, is that Ötzi did not die in the gully. He died outside it, or more precisely above it, and his dead body most likely rested in/on the snows of late winter. After freeze-drying on the surface of the snow, he and most of his belongings later entered into the gully as the snow and ice surrounding him melted away. Whether this happened the same year, later and/or in several steps is not known. Ötzi’s broken equipment and the missing pieces were caused by natural processes on the site, not a violent encounter prior to his death.

The question of the glacier

A central part of the original Ötzi story is that he died just as the climate was getting cooler. Snow and ice covered his resting place a short time after he died, sealing it off from the environment. Otherwise, the reasoning goes, the ice mummy and the artefacts would not have been preserved. This has even been used as an argument for glacier advance and climate cooling just when Ötzi died. As the ice built up, a glacier developed here. Since Ötzi was resting in a protected gully, he was not directly influenced by the moving ice of the glacier. Only 5300 years later did the glacial ice melt and Ötzi reappeared.

This type of preservation is at odds with the way other ice finds are preserved. Archaeological finds from the ice are mostly found in association with stagnant ice, i.e. ice that does not move. Non-moving ice can be found in isolated ice patches and in non-moving ice fields attached to moving glaciers. Due to their downhill movement and constant renewal of the ice, alpine glaciers only yield more recent finds, which normally do not even date back to the medieval period.

Since the discovery of Ötzi in 1991, no other similar finds have appeared from gullies beneath glaciers, even though glaciers in the Alps have retreated substantially due to the on-going warming. A number of human corpses and remains have emerged from the melting glaciers in the Alps and elsewhere, but none earlier than c. AD 1600 (more on this subject here). All the recent human remains have been found on the surface of glaciers, not below them. An artefact assemblage similar to Ötzi’s, but five hundred years younger and without the mummy, was discovered in the Schnidejoch pass in the Swiss Alps from 2003 onwards. This find was associated with non-moving ice in a slope just below the actual pass. There is a glacier here as well, but further downslope.

What is the evidence that there was moving ice in the location of Ötzi’s find spot? The excavators of the site actually write on the first page of their 1992 excavation report that the topography of the area surrounding the find spot is not advantageous to the development of a glacier. There is no catchment area for a glacier here and the area is quite flat, which would not have facilitated ice movement either.

In a 1996 paper on the glaciology of the area, Baroni and Orombelli writes that the Ötzi was found at the upper edge of the accumulation area of an alpine glacier, and that he was preserved in motionless ice inside a gully.

Orthophoto (vertical photo) of the find area, taken 1970-74. Ötzi findspot is marked with a red point,.
Orthophoto (vertical photo) of the find area, taken 1970-74. Ötzi findspot is marked with a red point, based on the original excavation data. The densely placed parallel stretchmarks (arrow) in the ice mark ice movement. A side-moraine is visible along the edge of the ice here. Illustration: Lars Pilø, secretsoftheice.com.

Aerial photos of the find spot from the early 1970ies have been produced by the Austrian mapping authorities. They can be accessed over the internet and imported to a GIS (Geographical Information System). This 1970-74 picture (above) does not show visible signs of ice movement at the marked find spot. However, the first traces of stretch marks from ice movement are visible only c. 50 m further east. There is also a lateral moraine deposited by a moving glacier present here, even though this moraine may date back to the termination of the last Ice Age.

The Ötzi findspot
The Ötzi find spot (tatsächlicher Fundort) in July 2012. Source

This information fits well with ground photos of the area. A 2012 photo (see above) shows that the find spot is situated in a flat area, close to the highest point on the ridge. From the find spot, the terrain slopes into a large gully in the area where the stretch marks are visible in the 1970ies aerial photo.

So far, the evidence presented here does not point to moving ice at the Ötzi find spot. However, the behavior of glaciers is a complicated matter. It is hard to say how the ice would have behaved here during times of more substantial presence of ice, for instance during the Little Ice Age (ca. AD 1300-1850). The excavators of the site state that there was c. 20 m of ice here in 1920, though the source for this information is not given. Glaciers may have basal sliding, as we can see further down the slope here, grinding their way into the terrain. Alternatively, glaciers may be frozen to the subsurface, showing only deformation of the upper ice layers – or a combination of the two. In our case, the presence of bedrock sticking up from the otherwise more level surface would have made basal sliding more difficult. Adding to this, the ice would need to be very thick to produce the basal heat necessary for sliding to start. Permafrost maps show that the find spot is well inside the permafrost zone. It is more likely that the ice was frozen on to the ground here without basal sliding.

There is another piece of evidence that points against basally-sliding ice over the find spot. Several of the artefacts were recovered not deep inside the gully, but further up on the sides of the rock ledges and stones constituting the gully. If a glacier had ground its way over here, how could they have been preserved? The most telling piece is the fragment of a birch bark vessel found outside the gully (mentioned above). How could it have survived a grinding glacier moving over the area?

Based on this discussion, it is more likely that a non-moving ice field developed over Ötzi’s resting place. Further downslope, this ice field became thicker, eventually developing into a classical moving glacier, which ground its way into the hillside. In the flat area, where the find was discovered, the ice did not become thick enough for basal sliding to happen after Ötzi died here.

A similar situation as at the Tisenjoch – the Storgrovbrean glacier in Jotunheimen, Oppland. The uppermost part of the glacier is a non-moving icefield, while the moving and grinding glacier develops further downslope. Photo: Lars Pilø, secretsoftheice.com.

Does it matter, whether Ötzi was buried below a moving glacier or a non-moving ice field? Is this not just a technicality? Not quite. Non-moving ice fields connected to glaciers are quite similar to isolated ice patches. They are thinner and less stable than glaciers, and more prone to periodic melt during shorter warming periods. If Ötzi was buried beneath a non-moving ice field of limited thickness, the body and the associated artefacts are more likely to have been repeatedly exposed to the environment. It would change the context of the Ötzi find from very special circumstances to quite normal find circumstances for ice finds.

Based on the published scientific works of the excavators and the glaciologists, there is no explicit mention of moving ice over the find spot. So how did this this concept become an integral part of the official Ötzi story? One possible explanation is that ice patches and non-moving ice fields are rare in the Alps due to the topography. There is not even an existing German word for ice patch, as frustrated German journalists have told me when they have tried to describe where we discover our finds here in Norway. Maybe the moving glacier idea simply stems from the fact that the site had been covered by ice, which in the Alps is equated with glaciers and that glaciers are commonly believed to move?

The question of the time capsule

The official story provides a single event situation with all the material found in the gully related to Ötzi. This would be a remarkable situation in glacial archaeology. Ice sites tend to accumulate material over time, not preserve one single event only, and especially not in mountain passes, where there is often quite a lot of human and natural activity over time.

What does the evidence say? If Ötzi and his equipment had been permanently buried by ice like in a time capsule, the radiocarbon-dated material from the gully should all derive from his time, at least no later. A 2014 report by Walter Kutschera and colleagues summarizing the available radiocarbon dates shows that this is not the case.  The material not related to Ötzi based on the radiocarbon dates is mostly of natural origin. The exception to this is a piece of cut green alder, radiocarbon-dated to 800-410 BC, i.e. the Hallstatt period.

Radiocarbon dates of material found in the gully together wiht Ötzi, but dated to earlier or alter periods. Source: Kutchera et al 2014, fig. 4.

The radiocarbon dates clearly show that material was repeatedly added to the assemblage in the gully. This could only have happened if the find spot was also repeatedly exposed. The gully started to collect material from c. 5300 BC and continued until c. 2000 BC. It is also worth noting that a piece of charcoal in the gully was dated to be about one thousand years older than Ötzi. He was not the first human on the site either.

The time of Ötzi’s death was during a period of advancing glacier. It makes sense that the find spot would eventually be covered by so much ice that it was completely sealed off. According to the radiocarbon dates, this appears to have happened around 1300 years after Ötzi’s death. In the mean time, material was added to the gully, which shows that the gully and its contents must have been exposed by melting.

However, if Ötzi’s body and the associated artefacts were repeatedly exposed, why are they still remarkably well preserved? Recent results from glacial archaeology indicate that material from the ice does not break down as fast as previously believed. We are beginning to understand that the combination of the cold, high altitude environment and the only short and intermittent exposure does not lead to a rapid destruction of the material. It deteriorates, but it is not as if it is exposed one year and gone the next. As mentioned above, wood naturally freeze-dries when exposed on ice sites and can preserve for many years while being intermittently exposed.

Ötzi after more melting
Ötzi as he appeared after melting had exposed more of his body. Notice the missing skin on in the back of his head, and the bared back without clothing. Source

If we look at Ötzi himself, the publication clearly says that the fur cape was much better preserved beneath the body, as was the footwear. In fact, the fur cape had fallen into pieces above his back, leading to his naked back being exposed when he melted out in 1991. The skin on the back of his head had also flaked off, exposing the cranial bone here. Tellingly, this is the highest point of the mummy – the area most likely to have been repeatedly exposed. There is reason to believe that the upper part of body was exposed on a number of occasions prior to the 1991 discovery.

Ötzi was not buried in the ice for 5300 years like in a time capsule. After being encased in the ice in the gully, he was intermittently exposed during melting incidents. This led to some damage to his body and the artefacts. The intermittent exposure of the gully led to the introduction of younger material to the finds assemblage, in addition to material already present here before Ötzi died. This tells us that scientists have to be careful in assigning undated material in the gully to Ötzi, something also mentioned by Heiss and Oeggl in their 2009 paper.

The amount of ice on the find spot has varied in recent years based on aerial photos. There is no gradual retreat of the ice, although the trend towards less ice is clear. Some years show extensive snow coverage, some show bare ground and exposed ice only in limited areas. In Ötzi’s time there would have been a similar trend, albeit opposite, towards more ice over time. However, the snow coverage would have varied from year to year then as well. An immediate and permanent burial of Ötzi and his artefacts is unlikely.

The new Ötzi story

About 5300 years ago, Ötzi died in a high mountain pass in the Alps. As the original story goes, he fled to the mountains with broken equipment, died in a gully and was quickly covered by snow and ice. The ice in the protected gully preserved him like in a time capsule, sealed beneath a moving glacier. He was saved by a miracle. This is the official Ötzi story still being told by the Ötzi Museum in Bolzano today. Based on new scientific papers, and our own experience from glacial archaeology in southern Norway, we have presented a different story, which we think fits the evidence better and does not need a string of lucky coincidences to account for the preservation.

Based on the available evidence, Ötzi lay on the snow where he died for a period. This allowed the body to freeze-dry, saving it for posterity. After some time, the snow and ice containing the body melted. Ötzi and most of his belongings slipped into a gully beneath, where the discovery was later made. This re-positioning of the find may have happened during one heavy melting situation, or during a series of smaller melting events. The missing parts of the equipment did not make it into the gully and were eventually lost. Snow and ice re-covered the gully. Ötzi was covered by a field of non-moving ice, not by a basally sliding glacier. Some of the equipment broke and displaced due to natural processes on the site.

During very warm summers, the ice-cold grave of Ötzi would occasionally re-open, as the ice cover was not very thick. This led to the deterioration of the most exposed parts of the body and the artefacts. At the same time, it allowed more recent material to enter the gully. About 2500 years ago, the climatic conditions for glacier advance became so favorable in the Alps that ice and snow finally sealed it off from its surroundings. Only at the end of the 20th century did the ice again melt back to a degree that re-exposed the body and the artefacts.

Looking at the Ötzi find this way, it is no longer an anomaly in the world of glacial archaeology, quite the contrary. Ötzi died on the snow, which is how most ice finds are originally lost. Together with the artefacts, he eventually melted down into a gully, a typical way topographical features will trap ice artefacts. The mummy and the artefacts were preserved by a non-moving field of ice, just like the other old finds from the ice. The find spot itself was not sealed of like a time capsule. More recent material is mixed with earlier finds as on other ice sites.

This new story is obviously not the appealing and clear narrative provided by the original Ötzi story, which combined a series of serendipitous circumstances to preserve a unique moment of the past. Maybe this is why the original story is still being told, even after new scientific evidence proved that it was unlikely.

Ötzi is still a fantastic find, but the find circumstances are not so special as claimed. In fact, they are quite normal for glacial archaeology. This is actually very good news. It means that the chances of finding another ice mummy are higher than previously believed, since a string of special circumstances are not needed for the preservation of this type of find. There may be more Ötzis out there waiting to be discovered!

Scientific publications on Ötzi, referred or used when writing this text, can be found here.