CT scans of 137 mummies from four major geographical regions spanning more than 4,000 years suggest that atherosclerosis was more common in ancient populations than previously thought.
The medical sciences have long believed that atherosclerosis is largely a disease of contemporary lifestyles although the pattern of its incidence and prevalence before the modern era was unknown.
The study, "Atherosclerosis across 4000 years of human history: the Horus study of four ancient populations,"
was published in the journal Lancet
. Access to mummified remains of ancient peoples gave the researchers a unique opportunity to assess pre-industrial populations for incidence of atherosclerosis.
Mummified remains studied came from ancient Egypt, ancient Perus, ancestral Puebloans of Southwestern Americas and hunter-gatherers from the Aleutian Islands.
The researchers were able to identify atherosclerosis in over one-third of the mummified specimens they studied and concluded from the incidence of calcified plaques in the wall of the arteries that hardening of the arteries may be a natural predisposition of human beings as part of the ageing process and not essentially the consequence of aspects of modern life style considered "unhealthy."
According to WebMD
, lead researcher Randall Thompson, of the University of Missouri Kansas City School of Medicine, had previously conducted studies that showed from evidence of studies of Egyptian mummies as old as 3,500 years that atherosclerotic heart disease existed among ancient Egyptians.
However, many experts believed that the observations from the study of ancient Egyptian mummies was due to the fact that they were mostly those of elites who lived significantly like modern humans on diets of animal products high in fats, and probably got little exercise.
However, the latest study extends the insight and raises questions about previous assumptions. It looks at the pattern across four distinct populations of ancient peoples with different lifestyles, such as the ancient Egyptians and Peruvians who were farmers, the ancestral Puebloans who were foragers and Unangans of the Aleutian Islands who were hunter-gatherers.
The researchers said
: "The diets of these peoples were quite disparate, as were the climates. Indigenous food plants varied greatly over the wide geographical distance between these regions of the world. Fish and game were present in all of the cultures, but protein sources varied from domesticated cattle among the Egyptians to an almost entirely marine diet among the Unangans."
The researchers conducted scans of 137 mummies with an estimated average age of 43 and found "probable or definite atherosclerosis" in 34% of the mummies. Atherosclerotic condition was defined with reference to calcified plaque in the wall of the artery.
The researchers observed that "atherosclerosis was common in four pre-industrial populations, including a pre-agricultural hunter-gather population, and across a wide span of human history. It remains prevalent in contemporary human beings. The presence of atherosclerosis in pre-modern human beings suggests that the disease is an inherent component of human aging and not associated with any specific diet or lifestyle."
Due to the fact that the study covered subjects with more diverse backgrounds, the researchers concluded that the pattern of incidence of hardening of arteries indicated that lifestyle and diet account only partly for the process of atherosclerotic degeneration of the arteries.
reports that study author Randall Thompson of Saint Luke’s Mid America Heart Institute, said in a statement:
"We found that heart disease is a serial killer that has been stalking mankind for thousands of years. In the last century, atherosclerotic vascular disease has replaced infectious disease as the leading cause of death across the developed world. A common assumption is that the rise in levels of atherosclerosis is predominantly lifestyle-related, and that if modern humans could emulate pre-industrial or even pre-agricultural lifestyles, that atherosclerosis, or at least its clinical manifestations, would be avoided. Our findings seem to cast doubt on that assumption, and at the very least, we think they suggest that our understanding of the causes of atherosclerosis is incomplete, and that it might be somehow inherent to the process of human aging."
The researchers suggested that atherosclerotic plaque formation may result from decreasing ability of the body to metabolize fat leading to a clogging of the arteries.
The Daily Mail
reports that Caleb Finch, professor of gerontology at the University of Southern California, who was involved in the study, said that longer human lifespans following introduction of antibiotics and improvements in living conditions means that more people survive long enough to experience age-related degenerative diseases.
Dr Frank Ruehli of the University of Zurich, who was not involved in the study, said the results suggest that predisposition to atherosclerosis may have a significant genetic element. He said: "Humans seem to have a particular vulnerability (to heart disease) and it will be interesting to see what genes are involved. This is a piece in the puzzle that may tell us something important about the evolution of disease."
However, other experts have called for caution in interpreting the evidence.
According to AP
, Dr Mike Knapton, associate medical director at the British Heart Foundation, said the pattern observed in the mummies may be due to other conditions. He said it was not clear that the patterns of calcification observed were the kind that result in heart attacks or strokes. He said: "It's a fascinating study but I'm not sure we can say atherosclerosis is an inevitable part of aging."
Similarly, lead researcher Thompson, advised people to cultivate healthy lifestyles, good diet, avoid smoking and lead an active life.
He said: "We don't have to end up like the mummies."