Atherosclerosis is a process in which the wall of an artery fills with fat, fibrous tissue and, in later stages, grains of calcium. If the “plaque” gets large enough, it limits the flow of blood. When that happens and tissue downstream from the blockage dies, the result is a heart attack or stroke.
The researchers used CT scanners to detect calcium in arteries. They looked in the aorta, which is the body’s main arterial trunk; the coronary arteries of the heart; the carotid arteries of the neck; and the arteries of the thigh and the lower leg.
When calcium was present, they concluded the person had atherosclerosis — a diagnosis supported by studies of living patients.
Of the 137 mummies, 76 were Egyptian, with the oldest from about 1800 B.C.; 51 Peruvian, from 900 B.C. to A.D. 1500; five Puebloan from the American West, from 1500 B.C. to A.D. 1500; and five Aleutian natives from the 18th, 19th and early 20th centuries.
Atherosclerosis was present in 38 percent of the Egyptians, 25 percent of the Peruvians, 40 percent of the Puebloans and 60 percent of the Alaska natives (although the number of mummies of the latter two groups is so small that the percentages are statistically meaningless).
Whether any of the mummified people died of atherosclerotic disease could not be determined.
Only the Egyptian bodies were intentionally preserved. The others were naturally mummified by the cold and dry conditions of the places where the people died. As a consequence, they may not be representative snapshots of their populations. Nevertheless, a few generalities stand out.
One of them is that atherosclerosis increases with age. Those with no sign of the condition had an average estimated age at death of 32 years. Slightly more than half the mummies in their 40s, however, had at least one calcified artery. For the few mummies older than 50, the prevalence was lower — about 40 percent.
Studies of present-day populations have found a similar increase in calcium with age as well as atherosclerosis in young adults.
A review of 3,832 autopsies done on troops who died in combat or of unintentional injuries in the Iraq and Afghanistan wars found that 9 percent had atherosclerosis in the coronaries. That’s a dramatic drop from the prevalence found in autopsies of casualties of the Korean (77 percent) and Vietnam (45 percent) wars.
Bruno Frohlich, a physical anthropologist recently retired from the Smithsonian Institution and a co-author of the study, said the team plans to examine more remains.
Next up are naturally mummified bodies from Mongolia and “bog people” preserved in peat deposits in Britain and Scandinavia.
The latter group may be hard to evaluate, however, because the bogs the bodies were thrown into (often following execution) had acidic water that dissolves calcium, including most of the bones.