The 1991 discovery by German tourists of a human body in the eastern Italian Alps rivals any fictional Indiana Jones adventure. Subsequently determined to be the oldest naturally preserved ice mummy, Otzi, or the Iceman as he is known, is now safely on display in Bolzano, Italy. Thanks to 21st-century technology, his remaims are still yielding secrets about how he lived, ate and survived in the extreme alpine environment in which he was found.
Which is why a solid lump of material, weighing about two grams, from the stomach of this 5,300-year-old Copper Age individual arrived at UTS in 2014 and was delivered into the hands of Professor Philip Doble, director of the Faculty of Science Elemental Bioimaging Facility.
“It looked like a piece of dried up old meat actually,” says Professor Doble who, with UTS colleague Dr David Bishop, became part of an extraordinary international collaboration of experts conducting the first in-depth analysis of the Iceman’s stomach contents.
Iceman had a high proportion of fat in his diet, supplemented with wild meat from ibex and red deer, cereals from einkorn, and with traces of toxic bracken.
Dr Frank Maixner
The researchers say the findings, published in Current Biology, offer important insights into the nutritional habits of ancient European individuals and also offer clues as to how our ancient ancestors handled food preparation. Among other things, their findings show that the Iceman's last meal was heavy on fat.
"By using a complementary multiomics approach combined with microscopy, we reconstructed the Iceman's last meal, showing that he had a remarkably high proportion of fat in his diet, supplemented with wild meat from ibex and red deer, cereals from [the ancient wheat grain] einkorn, and with traces of toxic bracken," says Dr Frank Maixner of the Eurac Research Institute for Mummy Studies in Bolzano.
Dr Maixner and colleagues explained that the analysis hadn't happened earlier because scientists were initially unable to identify the Iceman's stomach. That's because it had moved up during the mummification process. In 2009, his stomach was spotted during a re-investigation of CT scans, and an effort to analyse its contents was launched.
"The stomach material was, compared to previously analysed lower intestine samples, extraordinarily well preserved, and it also contained large amounts of unique biomolecules such as lipids, which opened new methodological opportunities to address our questions about Otzi's diet," Dr Maixner says.
The researchers combined classical microscopic and modern molecular approaches to determine the exact composition of the Iceman's diet prior to his death. The broad-spectrum approach allowed them to make inferences based on ancient DNA, proteins, metabolites and lipids.
Because of their expertise with elemental analysis the UTS team were given the task of measuring the metal contents of Otzi’s stomach using an ICPMS – a form of mass spectroscopy that uses a high temperature plasma source (ICP) to generate ions that are separated and detected by a mass spectrometer.
“The ICPMS is a highly sensitive elemental analyser that can detect and measure most elements on the periodic table. Through an industry partnership with Agilent Technologies we’ve been using this technology since 2002 and have established a reputation through the EBF as experts in this area,” Professor Doble says.
The levels of iron, copper and zinc found in the stomach contents were entirely consistent with what the Iceman had been eating, he says.
“There was no evidence of heavy metal contamination which was a possibility considering copper smelting was widely practised.”
The analysis identified ibex adipose tissue as the most likely fat source. In fact, about half of the stomach contents were composed of adipose fat. While the high-fat diet was unexpected, the researchers say it "totally makes sense" given the extreme alpine environment in which the Iceman lived and where he was found.
Professor Doble says it was exciting to be part of such an international scientific effort and that he’d relish the opportunity to analyse one of Otzi’s teeth.
“Teeth tell us a lot about the history of exposure to certain elements so we’d learn a lot from testing Otzi’s incisors,” he says.
More about the Iceman's last meal