Lessons From Ötzi, the Tyrolean Ice Man. Part II

Otzi's Diet

Otzi's digestive tract contains the remains of three meals.  They were composed of cooked grains (wheat bread and wheat grains), meat, roots, fruit and seeds (1, 2).  The meat came from three different animals-- chamois, red deer and ibex.  The "wheat" was actually not what we would think of as modern wheat, but an ancestral variety called einkorn.

Isotope analysis indicates that Otzi's habitual diet was primarily centered around plant foods, likely heavily dependent on grains but also incorporating a variety of other plants (3).  He died in the spring with a belly full of einkorn wheat.  Since wheat is harvested in the fall, this suggests that his culture stored grain and was dependent on it for most if not all of the year.  However, he also clearly ate meat and used leather made from his prey.  Researchers are still debating the quantity of meat in his diet, but it was probably secondary to grains and other plant foods. It isn't known whether or not he consumed dairy.

Otzi's diet would have been high in carbohydrate, mostly from einkorn wheat (and perhaps other grains) but also from fruit and possibly legumes.  It was probably moderate in protein, with the protein coming from grains, perhaps legumes and some meat.  He probably didn't eat much fat, but he did get some fat from nuts and meat.

Otzi's Health

Otzi was about 45 years old at the time of his death, had a lean and fit physique, and stood roughly 5 feet, 5 inches tall (1.65 m).  This adult male height is typical of hunter-gatherers and other non-industrial people throughout the world today (except those that rely heavily on dairy), but that's a topic for another post. 

Otzi was not exactly the picture of health.  He suffered from a number of health problems, both infectious and non-infectious in nature. 

Like nearly all non-industrial populations, Otzi probably had intestinal parasites; in his case, his colon contained whipworm eggs (4).  Lines in his fingernails showed signs of an unknown illness that occurred three times in the four months before his death.  His body also bears DNA evidence that he may have been infected with Lyme disease, a serious chronic bacterial infection transmitted by tick bites (5).

Otzi's body also shows signs of a number of non-infectious disease processes.  Several of his major arteries were calcified-- suggesting advanced vascular disease that's normally associated with an elevated heart attack risk.   He had three gallstones, which has been used to support the idea that he ate a lot of animal fat, but this seems like a major leap of faith to me.  He had arthritis in several locations, including the spine and hips (6).  He had cavities and periodontitis (6a).  His lungs were blackened, presumably from the smoke of fires used for various purposes, including smelting copper.

Perspective

Otzi is probably fairly representative of early agriculturalists in some ways, and to a lesser extent, the hunter-gatherers that preceded him.  The archaeological (skeletal) record shows evidence of severe physical stress in early agriculturalists, including short stature, cavities, and skeletal abnormalities, which probably reflect both nutritional and infectious stress (Cohen and Crane-Kramer. Ancient Health. 2007; Cohen. Health and the Rise of Civilization. 1991).

The shift to agriculture involved a major change in diet, away from a hunter-gatherer diet composed of diverse wild plant and animal foods, to a diet centered around grains.  Although some humans may have eaten grains for tens of thousands of years before domesticating plants, grains clearly became a more central source of food during the Neolithic. This posed a number of nutritional problems that would have exerted selective pressure over time, favoring genetic adaptations to the new diet.  Later agriculturalists were taller and healthier than early agriculturalists, probably due to a combination of genetic and cultural adaptations (Cohen and Armelagos. Paleopathology at the Origins of Agriculture. 1984).

The more sedentary lifestyle, higher population density, and contact with livestock associated with agricultural life created new opportunities for human pathogens (Cohen. Health and the Rise of Civilization. 1991).  A number of parasites, bacteria and viruses took advantage of the situation, becoming more diverse and virulent and giving rise to many of the most problematic infectious diseases we know today.  These new infectious threats were extremely debilitating and deadly for early adopters of agriculture in Eurasia, just as they were for unexposed populations when Europeans reached the Americas.  However, the strong selective pressures they exerted on the ancestors of modern Eurasians gave rise to a number of protective genetic adaptations, the traces of which are highly visible in our modern genomes. 

Otzi's health is clearly not something to aspire to.  In some ways, it's representative of contemporary hunter-gatherers and non-industrial agriculturalists: his leanness and probable lack of metabolic disorders such as diabetes, as well as the presence of intestinal parasites and other infectious diseases.  In other ways, some of the findings are surprising: his cardiovascular disease and gallstones, which are considered "diseases of affluence" today.

I think we have to take the cardiovascular disease with a grain of salt.  Modern-day non-industrial agriculturalists typically have low levels of atherosclerosis (a thickening and degeneration of the vascular wall) compared with affluent nations, even if the diet is grain-heavy, although they are not free from atherosclerosis (7).  No one knows how much atherosclerosis hunter-gatherers have, because no one has ever done cardiac autopsies to my knowledge.  But we do know they have low blood pressure, low circulating lipids, and high physical fitness, which argues against the presence of serious vascular disease.  Otzi was exposed to high levels of copper and arsenic from smelting, particulate matter from smoke, and Lyme disease.  He also had a genetic predisposition to cardiovascular disease, which I'll discuss later.  It's likely that at least some of these factors contributed to his cardiovascular disease, and in addition it's hard to know how representative he was of his culture.

The other thing to keep in mind is that having atherosclerosis doesn't necessarily mean a person will have a heart attack.  There are other important components of risk, including the tendency of the blood to clot, the tendency of the heart to enter fibrillation (irregular contraction that can be fatal), blood vessel diameter, and the stability of plaque in the artery wall.  These may explain why some non-industrial populations have a much lower heart attack risk than would be predicted from their degree of vascular disease (8).  The point is that just because Otzi had signs of advanced atherosclerosis, does not necessarily mean he was about to have a heart attack.

In the next post, I'll delve into Otzi's genome, and the insights it contains into the evolution and health of modern Europeans.