In his final days, the Iceman ate a hearty mountaineers diet of red deer, wild goat, and whole grain einkorn wheat—but he may also have accidentally eaten toxic ferns.
Even after being chewed up, swallowed, partially digested in Ötzis stomach, and then frozen in a glacier for 5,300 years, some bits of Ötzis last meal are still recognizable, at least under a microscope. Frank Maixner of the Eurac Research Institute for Mummy Studies and his colleagues saw compact bits of fatty tissue and bundles of muscle fibers, mixed with pollen from a genus of wheat called einkorn, which grows wild in the region but also includes some of the earliest domesticated wheat species. Mixed in with the partly-digested food bits, however, were spores from a fern called bracken, which is toxic to humans and other animals if not properly prepared.
Red meat and healthy whole grains
Chemically, the remnants of Ötzis partially digested meal contained a compound called phytanic acid, which is a hallmark of fat or dairy products from ruminants like cattle, deer, and goats. There were also minerals like calcium, iron, magnesium, sodium, and zinc, all of which are found in red meat and dairy products. And among the 167 different animal and plant proteins in the samples, Maixner and his colleagues found six that are specific to structures in the long contracting threads in ibex skeletal muscles—leg of wild goat, perhaps. Another protein in the mix is found only in deer muscles.
In a metagenomic analysis of the samples, Maixner and his colleagues confirmed this by finding segments of DNA belonging to red deer and ibex. So thats what Ötzi was eating, but how did he prepare it? An earlier study of samples from his lower intestine found some traces of charcoal, suggesting that his food had been cooked over a fire, and when Maixner and his colleagues compared the microscopic bits of meat in Ötzis stomach to some meat they dried experimentally, they got a decent match.
“A slow drying or smoking of the meat over the fire would explain the charcoal particles detected previously in the lower intestine content,” Maixner and his colleagues wrote, although they add that the meat could also have been eaten fresh. Dried meat would have been ideal for long treks through the mountains, as modern hikers know.
To go along with the einkorn pollen, Maixner and his colleagues chemical analysis found a compound called azelaic acid, which usually shows up in whole grain cereals. And of the proteins in the sample, 13 are found only in einkorns genus, mostly in the inner contents and the outer layer, or pericarp, of the seeds. That strongly suggests that Ötzi was eating whole grains of einkorn, though its not clear how theyd been prepared or processed. DNA analysis also found segments of ancient einkorn DNA, along with some fungal sequences.
“These data suggest that the Icemans last meal was well-balanced in terms of essential minerals required for good health,” wrote Maixner and his colleagues.
High-fat meals and clogged arteries
Ötzis diet was extremely high in fat. Fat residue made up between 27 and 64 percent of his stomach contents—an unexpected discovery that Maixner and his colleagues say makes perfect sense in retrospect.
“The high and cold environment is particularly challenging for the human physiology and requires optimal nutrient supply to avoid rapid starvation and energy loss,” Maixner and his colleagues wrote. “The Iceman seems to have been fully aware that fat represents an excellent energy source.” Its molecular composition suggests that most of the fat came either from goat dairy products or body fat.
But although Ötzis fatty diet may have been an optimal way to get and keep enough calories to survive an energetic lifestyle in the frigid, high-altitude environment of the Alps, it may still have taken a toll on his health. A previous CT scan revealed that fatty deposits clogged several of Ötzis arteries in a condition called atherosclerosis. From Ötzis genome, we know that he was genetically vulnerable to arterial disease, and its easy to imagine how that genetic predisposition may have interacted with his diet to cause him cardiovascular trouble by the time he reached middle age.
Medicine or poison?
Microscopic perusal of Ötzis churned-up food also revealed bracken spores, which raised some questions about how and why Ötzi ingested spores from a plant thats normally toxic to humans (it's also not good for grazing animals like horses and cattle). Eaten raw, bracken can cause abdominal pain, constipation, and other symptoms. When cooked properly, young bracken fronds, called fiddleheads, are a delicacy in many countries. (That may not be a great thing, as recent studies have linked that a chemical contained in the fern, ptaquiloside, to certain forms of throat, stomach, and urinary tract cancer in both humans and grazing animals.)
And in folk medicine around the world, bracken is often consumed as a remedy for intestinal problems—which we know plagued Ötzi during his life. In fact, some of the mushrooms found in one of his pouches are also commonly used to treat intestinal ailments, so its clear that he was seeking relief. He might have turned to a bracken preparation, too.
But its also possible that Ötzi ate toxic fern spores accidentally. Maixner and his colleagues suggest that he may have wrapped is food in bracken leaves, thus accidentally contaminating his last meal with the toxic spores. Its not clear whether he lived long enough to regret that mistake, if so.
Chemical analysis of Ötzis last meal also revealed a compound called gamma-terpinene, which is often found in herbal oils such as coriander oil, lemon oil, and others, suggesting that Ötzi used herbs, either as medicine, as seasoning for his food, or both.
The remains of Ötzis last meal were also dusted with tree and shrub pollen that probably settled onto his food while he was eating. Because the pollens came from plants that grow at different altitudes on the Alpine slopes, archaeologists have previously used samples of those pollens, collected from Ötzis lower intestines, to help reconstruct the series of ascents and descents that marked his hectic final days.