How good was Ötzi's clothes?

Scientists study wearing comfort in the Stone Age

At the Hohenstein Institutes in Bönnigheim the team of Professor dr. Karl-Heinz Umbach (right) modern functional textiles in terms of wearing comfort with replicas of the equipment found at the Ötzi glacier mummy. © Hohenstein Institute
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How well did the clothing made of fur and leather protect people in the Neolithic Age from the weather? How does the clothing of Ötzi and Co. compare to modern functional textiles? Researchers at the Hohenstein Institutes investigated these questions as part of the project "Living Science - Stone Age" of the Southwest Broadcasting Corporation (SWR). Result: For example, in terms of breathability cut the Stone Age leather clothing in comparison to modern functional clothing bad. Only the loincloth made of buckskin reached acceptable levels. A modern outdoor or trekking clothing would therefore have significantly improved Ötzi's performance when hunting or crossing the Alps.

The task of the Hohenstein research team was to determine how warm Stone Age garments had held their wearer compared to today's products, in which ambient temperature or activity he sweated too much and how long he could hunt, for example, without having to give up exhausted.

To this end, the subjective impressions of volunteers who had crossed the Alps in the summer of 2006 should be compared with objective assessments of the thermal insulation, breathability and water and wind resistance of the worn garments. While the first group of probands had been equipped with modern functional textiles for their multi-day march, the second group only had reconstructions of equipment found in the approximately 5, 300-year-old glacier coral on the Tisenjoch in the Ötztal Alps.

Comfort under the microscope

The team of Professor Karl-Heinz Umbach used standardized examination methods with the Hohenstein skin model and the thermal mannequin Charlie for the objective assessment of wearing comfort.

These so-called thermoregulation models are used to determine the wearing comfort of clothing objectively by using them to replicate the sweating and heat loss of people. On the basis of the measured values ​​for heat insulation and moisture transport, it is then also possible to make reliable predictions about the temperature range for which clothes and combinations, but also sleeping bags and bedding, are suitable. display

When assessing breathability, Stone Age leather clothing performed poorly compared to modern functional clothing. Only the loincloth made of buckskin reached acceptable levels. Hohenstein Institute

Important factors for the wearing comfort of a garment or system are its ability to absorb vaporous as well as liquid perspiration and to dissipate it from the body. In the corresponding laboratory investigations for the determination of the respiratory activity and the perspiration transport the today's functional textiles out of or with chemical fibers showed the Neolithic counterparts out of leather and fur clearly superior. For example, the breathability of the modern T-shirt was 5.5 times higher than that of the leather shirt, whose material had also been used in leggings and arm-arms. According to the results of the study, the transport of liquid sweat has a value of about 3.6 times higher.

Problem moisture

The particularly soft deerskin of the loincloth, on the other hand, surprised the researchers with good values ​​in both breathability and sweat transport, but only played a minor role in the entire clothing system from the covered skin area.

The determination of the drying time on the body showed, according to the study, one of the main problems of the Stone Age clothing system: due to rain or sweating at strong physical effort introduced moisture was released slowly to the environment. The leather shirt, leggings and arm warmers needed about 6.1 hours to dry, the loincloth about 42 minutes.

As water is an excellent thermal conductor, the body cools down over wet clothing quickly. Along with the deprivation of energy from the drying clothes, the long drying times for tzi and his contemporaries not only limited their wearing comfort, but also posed a great health hazard (subculture) COUNTING). In comparison, the drying times of the modern fleece pullover and hiking pants of about 30 minutes and the T-shirt of about 19 minutes were moderate, according to the researchers. In addition, the outdoor jacket made of membrane material proved to be impermeable to moisture from outside, and this with good breathability.

Charlie in action

Kupfermann in the Stone Age robe: In order to assess the thermal insulation of garments under the influence of body movements and wind, the thermal manikin made of copper moved in a climatic chamber. Hohenstein Institute

As a further important factor for the wearing comfort, the scientists from Hohenstein used the thermal mannequin Charlie to investigate the heat insulation of the Stone Age and modern clothing systems in relation to different body regions and levels of activity - standing, walking - of the wearer with a typical wind movement of 7.2 kilometers per kilometer Hour (km / h). When looking at the overall body, Ötzi's coat and leather clothing without a grass coat showed a slightly higher thermal insulation (+8.7 percent) than the modern garments chosen by the SWR. However, according to the scientists, this is not a fundamental result. The SWR team did not use special trekking clothing when choosing modern clothing, but chose items designed for shorter outdoor use, for example as part of a one-day hike in medium climates.

Umbach therefore contrasted his research results with those for trekking clothing, which is geared to multi-day outdoor stays in extreme climatic conditions and whose degree of specialization corresponds to the clothing system of the Stone Age Ötzi. Relative to the weight, however, the modern clothing had a significantly better thermal insulation than the comparison models of fur and leather. In the case of the large stretches that had to be covered during the crossing of the Alps, as well as during hunting trips, the weight to be transported required for the required thermal insulation significantly burdened the Stone Age people physically, according to the researchers.

Grass coat as a seat pad?

Among other things, the Hohenstein scientists wanted to clarify the purpose of the grass mantle that the Stone Age hunter Ötzi carried with them. Speculation that this was mainly used as wind and rain protection, however, have been refuted by the laboratory studies. Thus, the grass mantle merely increased the total thermal insulation of the Stone Age outfit by 7.3 percent. Due to the coarse weave structure of the grass mantle, both wind and moisture were able to pass through largely unhindered, in contrast to modern outdoor clothing. Therefore, the team of Umbach assumes that the grass coat was also used as a seat pad during breaks and at night.

Also touch sensations, which are caused by the different pieces of clothing on the skin, were determined by the Hohenstein scientists in the context of the laboratory comfort tests. For example, especially the Stone Age shirt, leggings and arm warmers are characterized by a great rigidity of the processed leather in a skin sensory negative way. The summary of the thermophysiological - heat insulation, breathability, sweat transport and skin sensory evaluation showed a wearing comfort grade of 4.9 or insufficient for the loincloth and 6.0 (= insufficient) for the leather shirt, leggings and arm warmers.

According to the scientists, the modern T-shirt, the fleece sweater, the hiking pants and a special trekking trousers with grades score from very good to satisfactorily much better.

Comfort range of clothing detected

On the basis of the examination results, the Hohenstein researchers determined the so-called comfort range for the individual clothing systems, ie the temperature range in which the wearer feels comfortable, without overly sweating or freezing. When compared with the modern clothing chosen by the SWR, the slightly higher thermal insulation of Stone Age leather and fur clothing, for example, leads to Ötzi wearing his outfit at comparatively lower temperatures without freezing.

Thus, the clothes kept Ötzi in his Alpine crossing in the wind at 7.2 km / h at temperatures over about -5 C sufficiently warm. From this, the scientists conclude that it was either 5, 300 years warmer in the Alps than it is today, or that tzi was traveling in the warmer months or not even more or even heavier clothing wanted or wanted to carry with them and thus took a strong freezing approvingly accepted.

Especially during physical exertion, such as hiking or hunting, modern clothing can exploit its advantages in breathing and sweat transport: Based on a relative humidity of 50 percent, the wearer of the Modern clothing system 2 sweat excessively only at 28 C, in the Stone Age clothing system 1 without grass coat this would already be the case at 11 C. When hunting at an ambient temperature of + 5 C tzi threatened circulatory collapse after about 45 minutes, as his body was no longer sufficiently cooled due to the limited breathability of the clothing.

tzi's clothes with mangles

The stone-age fur and leather clothing found at tzi has thermal insulation values ​​designed for temperatures above -5 C. In periods of great physical activity, such as walking and hunting, the poor breathability and limited ability to transport liquid sweat led to the performance of the wearer was lowered very rapidly. In addition, the long drying times of clothing caused by the imminent cooling of the body poses a health risk, according to the researchers.

A modern outdoor or trekking clothing offers overall better performance in terms of comfort and physiological function and would have the ability tzis in activities such as the physically strenuous crossing of the Alps and the accompanying hunting clearly improved.

The results of the clothing physiology studies at the Hohenstein Institutes flow into the new SWR format "living science".

(idw - Hohenstein Institute, 29.05.2007 - DLO)