Scholarly article on topic 'Why Did Ancient People Have Atherosclerosis?'

Why Did Ancient People Have Atherosclerosis? Academic research paper on "History and archaeology"

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Abstract of research paper on History and archaeology, author of scientific article — Gregory S. Thomas, L. Samuel Wann, Adel H. Allam, Randall C. Thompson, David E. Michalik, et al.

Abstract Computed tomographic findings of atherosclerosis in the ancient cultures of Egypt, Peru, the American Southwest and the Aleutian Islands challenge our understanding of the fundamental causes of atherosclerosis. Could these findings be true? Is so, what traditional risk factors might be present in these cultures that could explain this apparent paradox? The recent computed tomographic findings are consistent with multiple autopsy studies dating as far back as 1852 that demonstrate calcific atherosclerosis in ancient Egyptians and Peruvians. A nontraditional cause of atherosclerosis that could explain this burden of atherosclerosis is the microbial and parasitic inflammatory burden likely to be present in ancient cultures inherently lacking modern hygiene and antimicrobials. Patients with chronic systemic inflammatory diseases of today, including systemic lupus erythematosus, rheumatoid arthritis, and human immunodeficiency virus infection, experience premature atherosclerosis and coronary events. Might the chronic inflammatory load of ancient times secondary to infection have resulted in atherosclerosis? Smoke inhalation from the use of open fires for daily cooking and illumination represents another potential cause. Undiscovered risk factors could also have been present, potential causes that technologically cannot currently be measured in our serum or other tissue. A synthesis of these findings suggests that a gene-environmental interplay is causal for atherosclerosis. That is, humans have an inherent genetic susceptibility to atherosclerosis, whereas the speed and severity of its development are secondary to known and potentially unknown environmental factors.

Academic research paper on topic "Why Did Ancient People Have Atherosclerosis?"

STATE-OF-THE-ART REVIEW gREVIEW

Why Did Ancient People Have Atherosclerosis?

From Autopsies to Computed Tomography to Potential Causes

Gregory S. Thomas*'"1", L. Samuel Wannz, Adel H. Allamx, Randall C. Thompson", David E. Michalik1

M. Linda Sutherland , James D. Sutherland**, Guido P. LombardiTT, Lucia Watson11, Samantha L. Cox: Clide M. Valladolid11, Gomaa Abd el-Maksoud##, Muhammad Al-Tohamy Soliman***, Ibrahem Badr Abd el-Halim Nur el-dinw, Emily M. Clarke§§§, Ian G.Thomas""", Michael I. Miyamoto111,

Hillard S. Kaplan" Caleb E. Finch"""

Bruno Frohlich****, Jagat Narulayttt, Alexandre F. R. Stewartzm, Albert Zink

Long Beach, CA, USA; Irvine, CA, USA; Milwaukee, WI, USA; Cairo, Egypt; Kansas City, MO, USA; Newport Beach, CA, USA; Laguna Hills, CA, USA; Lima, Peru; Mexico City, Mexico; Cambridge, United Kingdom; Philadelphia, PA, USA; Giza, Egypt; Alexandria, Egypt; 6th of October City, Egypt; Los Angeles, CA, USA; Middlebury, VT, USA; Mission Viejo, CA, USA; Albuquerque, NM, USA; Washington, DC, USA; New York, NY, USA; Ottawa, Ontario, Canada; and Bolzano/Bozen, Italy

ABSTRACT

Computed tomographic findings of atherosclerosis in the ancient cultures of Egypt, Peru, the American Southwest and the Aleutian Islands challenge our understanding of the fundamental causes of atherosclerosis. Could these findings be true? Is so, what traditional risk factors might be present in these cultures that could explain this apparent paradox? The recent computed tomographic findings are consistent with multiple autopsy studies dating as far back as 1852 that demonstrate calcific atherosclerosis in ancient Egyptians and Peruvians. A nontraditional cause of atherosclerosis that could explain this burden of atherosclerosis is the microbial and parasitic inflammatory burden likely to be present in ancient cultures inherently lacking modern hygiene and antimicrobials. Patients with chronic systemic inflammatory diseases of today, including systemic lupus erythematosus, rheumatoid arthritis, and human immunodeficiency virus infection, experience premature atherosclerosis and coronary events. Might the chronic inflammatory load of ancient times secondary to infection have resulted in atherosclerosis? Smoke inhalation from the use of open fires for daily cooking and illumination represents another potential cause. Undiscovered risk factors could also have been present, potential causes that technologically cannot currently be measured in our serum or other tissue. A synthesis of these findings suggests that a gene-environmental interplay is causal for atherosclerosis. That is, humans have an inherent genetic susceptibility to atherosclerosis, whereas the speed and severity of its development are secondary to known and potentially unknown environmental factors.

Steeped in the importance of modern lifestyles as causal in the development of atherosclerosis, most physicians are surprised when confronted with studies demonstrating that ancient people also had atherosclerosis. This new information does not easily fit into our understanding of its pathogenesis. When reading a new manuscript in a journal, we want to determine if the new information changes our ideas about a disease. Shall we behave or think differently? This is more easily accomplished if the new information builds on our current understanding of disease pathophysiology, diagnosis, or treatment. However, if it challenges the foundation of our understanding of the disease, the new information is much more challenging to process.

Such is case when physicians are faced with studies demonstrating atherosclerosis in ancient Egyptians, Peruvians, and Native Americans [1—4]. How do physicians and scientists square this with their understanding of atherosclerosis' causes? We reach for traditional risk factors: the

diets of these ancient people must have been rich; they were inactive; they must have had a harmful lifestyle in some way. But what if none of these were the case?

The Horus Team's discoveries challenge our current understanding of the causes of atherosclerosis. A review of past studies, however, demonstrates that while we have extended previous work, we have indeed built on the foundations of past investigators. Following this initial review, we will examine how we can integrate this new information and explore potential causes of atherosclerosis in ancient peoples.

AUTOPSY STUDIES

In one of the earliest published autopsies in which a light microscope was used, physiologist Johann Nepomuk Czer-mak (Fig. 1A) described the autopsy findings of 2 ancient Egyptian mummies curated by the Physiologic Institute of

This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/ licenses/by-nc-nd/3.0/). This study was supported by grants from the National Endowment for the Humanities and the Paleo-cardiology Foundation. The authors report no relationships that could be construed as a conflict of interest.

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. From the *MemorialCare Heart & Vascular Institute, Long Beach Memorial, Long Beach, CA, USA; fUniversity of California, Irvine, Irvine, CA, USA; {Cardiovascular Physicians, Columbia St. Mary's Healthcare, Milwaukee, WI, USA; §Al-Azhar University, Cairo, Egypt; ||Saint Luke's Mid America Heart Institute, University of Missouri-Kansas City, Kansas City, MO, USA; {Miller Children's Hospital of Long Beach, Long Beach, CA, USA; #Newport Diagnostic Center, Newport Beach, CA, USA; "Saddleback Memorial Medical Center, Laguna Hills, CA, USA; ffUniversidad Peruana Cayetano Heredia, Lima, Peru; {{Universidad Nacional Autónoma de México, Mexico City, Mexico; §§Department of Archeology, University of Cambridge, Cambridge, United Kingdom; || Penn Museum, University of Pennsylvania, Philadelphia, PA, USA; {{Museo de Sitio Puruchuco—Arturo Jimenez Borja, Lima, Peru; ##Faculty of Archaeology, Cairo University, Giza, Egypt; ***Biological Anthropology Department, Medical Research Division, National Research Centre, Cairo, Egypt; fffHigh Institute for Tourism and Hotel and Conservation of Archeology, Alexandria, Egypt; {{{University for Science and Technology, 6th of October City, Egypt;

§§§University of California—Los Angeles, Los Angeles, CA, USA; ||||||Middlebury College, Middlebury, VT, USA; {{{Mission Heritage Medical Group, St. Joseph Heritage Health, Mission Viejo, CA, USA; ###Depart-ment of Anthropology, University of New Mexico, Albuquerque, NM, USA; ****National Museum of Natural History, Smithsonian Institution, Washington, DC, USA; ftttZena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; {{{{John and Jennifer Ruddy Canadian Cardiovascular Genetics Centre, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; §§§§Institute for Mummies and the Iceman, European Academy of Bol-zano/Bozen (EURAC), Bol-zano/Bozen, Italy; and the ||||||||Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA. Correspondence: G. S. Thomas (gthomas1@memorialcare. org).

GLOBAL HEART © 2014 World Heart Federation (Geneva). Published by Elsevier Ltd. All rights reserved. VOL. 9, NO. 2, 2014 ISSN 2211-8160/$36.00. http://dx.doi.org/10.1016/ j.gheart.2014.04.002

Prague [5]. He described 1 mummy as a poorly preserved youth with few organs available for study. The second mummy, however, was a better preserved adult woman. Though her heart and lungs had been removed, her entire aortic arch was present and could be evaluated. Microscopic evaluation demonstrated that the anterior wall of the descending thoracic aorta contained "multiple considerably large and calcified plaques." Czermak was not only a pioneer in the then un-named field of paleopathology, he and neurologist Ludwig Tuerck later spearheaded the introduction of the laryngoscope into medicine [6,7].

With permission from Gaston Maspero, director of the Egyptian Museum and Antiquities Service, Cairo University, anatomy professor Grafton Elliot Smith (Fig. 1B) "unrolled" the mummy of the Pharaoh Menephtah on July 8,1907, in the Cairo Museum [8]. Menephtah, the 13th son and successor of Ramses II (Ramses the Great) ruled Egypt from 1213 to 1203 BCE. "Unrolling" of the linen wrappings of a mummy by this time had become a euphemism for unwrapping a mummy and performing a gross autopsy. Wrapped in fine linen, the well-preserved Menephtah was bald, and what little hair he had was white [8]. Upon gross examination of the aorta, Smith described it as "affected with severe atheromatous disease, large calcified patches being distinctly visible" [9]. In another rendition, he commented, "the aorta was in an extreme stage of calcareous degeneration, large bone-like patches standing out prominently from the walls of the vessel" [8].

Smith sent 3 cm of the mummified aorta for further examination to Samuel George Shattock, curator of the Pathologic Section of the Royal College of Surgeons' Museum in London. Publishing in the Proceedings of the Royal Society of Medicine, Shattock confirmed the microscopic presence of calcific atherosclerosis, which was up to 6 mm in length [9].

The mummified remains of Pharaoh Menephtah are curated in the Royal Mummy Room of the Cairo Museum, now called the Egyptian National Museum of Antiquities. His nameplate declares that he had suffered from arteriosclerosis. This provocative description stimulated the development of a team in February 2008, eventually named Horus, which sought to determine if the nameplate was indeed correct [10]. Not being aware of Smith's [8] and Shattock's [9] work from a century ago, we were skeptical.

While Smith was performing gross autopsies of often royal mummies housed at the Cairo Museum, Marc Armand Ruffer (Fig. 1C) was supplied mummy parts and a few intact mummies from the archeological expeditions of Smith, Flinders Petrie, Douglas Deary, Henry Keatinge, and Gaston Maspero [11]. The dam at Aswan was soon to be elevated and the anticipated upstream flooding provided the impetus for the expeditions to recover specimens that would be covered in water [12]. As the bulk of the specimens provided were limbs and thus not of use as museum pieces, Ruffer described no hesitation in dissecting them. Presenting his initial work in July 1908 at meetings of the British Medical Association in Sheffield, England, and the Cairo Scientific Society in December 1908 [13], Ruffer published his results in 1910 and 1911 [11,13]. He described atherosclerosis to be as common in ancient Egypt as it was in his time. Using visual and microscopic evaluation of approximately 2 dozen specimens, he commented, "When we consider that few of the arteries examined were quite healthy, it would appear that such lesions were as frequent three thousand years ago as they are today." Commenting further, regarding the "nature of the lesions. There can be no doubt respecting the calcification of the arteries, and that it is of exactly of the same nature as we see at the present day, namely,

FIGURE 1. Johann Czermak, Grafton Elliot Smith, and Mark Armand Ruffer. (A) Portrait of Johann Czermak (public domain), via Wikimedia Commons. (B) Portrait of Grafton Elliot Smith by John Cooke in 1915 (public domain), via Wikimedia Commons. (C) Portrait of Mark Armand Ruffer during service as an Egyptian official. Courtesy Timothy Weakley.

calcification following on atheroma." He described atherosclerosis in the carotid, subclavian, aorta, iliac, femoral, profunda, perineal, posterior tibial, and brachial and ulnar arteries. While Ruffer was aware of the findings of Shattock's limited autopsy, he was not aware of those of Czermak [14,15].

On the basis of his findings of atherosclerosis and other ancient Egyptian diseases including schistosomiasis, smallpox, pyorrhea (severe periodontitis), tuberculosis, abscesses, and urinary calculi, Ruffer is regarded as the father of paleo-pathology [14]. Among Ruffer's legacies is the chemical solution that now bears his name. Needing to soften the hard and brittle mummified tissue to enable sectioning for microscopic analysis, Ruffer showed that soaking specimens in a solution of alcohol, 100 parts, and 5% carbonate of soda solution, 60 parts, caused a gradual softening of the tissues over a period of days to weeks [15]. This also required a daily adjustment of the alcohol percentage.

In 1927, University of Buffalo pathologist Hubert U. Williams reported the results of a gross and microscopic autopsy of a mummy from the Lima area of Peru, circa 700 CE provided by the Field Museum of Natural History of Chicago. Calcific arteriosclerosis with thrombus formation was present in the right posterior tibial artery [16].

The first description of atherosclerosis of the coronary arteries of any ancient mummy was in 1931 by another University of Buffalo pathologist Allen R. Long with the autopsy of Lady Teye, an ancient Egyptian woman of approximately 50 years of age supplied by the Metropolitan Museum of Art, New York [17]. Atherosclerosis was also present in her aorta and renal arteries.

In 1955, Andrew Tawse Sandison performed histo-logic evaluations of available tissue of multiple Egyptian mummies using the increasing sophisticated staining and microscopic techniques of his time. To do so, he developed an often-used modification of Ruffer solution. Sandison confirmed these early reports with his documentation of the not infrequent presence of atherosclerosis in a number of ancient Egyptian mummies [18].

Decades later, Michael Zimmerman demonstrated the presence of atherosclerosis in 2 mummified Aleutian Islanders [19,20] and an Inuit woman [20]. Each also suffered from pulmonary anthracosis, consistent with significant smoke exposure during their lifetimes [19—21].

RADIOGRAPHIC STUDIES

Examining x-rays of Egyptian and Peruvian mummies at the Field Museum of Natural History, in Chicago, Roy Moodie [22] was the first to report x-ray evidence of atherosclerosis in 1931. Atherosclerosis was apparent in the arteries overlaying the scapula and ribs and in the forearm of a pre-dynastic Egyptian woman, dating prior to 3100 bce. Moodie [22] described the artery in the forearm as resembling a piece of badly kinked heavy wire.

The development of computed tomography (CT) scanning by Godfrey Hounsfield in 1971 substantially

improved the ability to evaluate arteries radiographically. William Murphy [23], Paul Gostner et al. [24], for example, demonstrated calcific atherosclerosis in both carotids, the distal aorta and right iliac artery in Otzi the Iceman, a European mummy dating back to 3300 BCE. Their discovery represents the earliest documentation of atherosclerosis in humans.

Similarly, Wybren Taconis, George Maat, and Maarten Raven [25] described the results of the CT examinations of ancient Egyptian mummies housed at the National Museum of Antiquities in Leiden. Arterial calcifications were found in 3 mummies: the upper and lower extremities of a woman approximately 40 to 52 years of age, and in the lower extremities of 2 men approximately 40 to 47 and 45 to 55 years of age, respectively.

HORUS TEAM FINDINGS

Given this pioneering work, in retrospect, it should not be surprising that the Horus Team found CT evidence of atherosclerosis in 29 of 76 ancient Egyptian mummies (38%). That atherosclerosis was present in 23 of 61 mummies (37%) from Peru, the American Southwest, and the remote Aleutian Islands was not anticipated [25]. The Peruvians and Native Americans of the American Southwest were prehistoric people and the Aleutians were hunter-gatherers [1].

We suggest that a gene-environment interplay [26] is the most likely explanation for the presence of atherosclerosis in these 4 disparate cultures. That is, the genes that make us human render us susceptible or vulnerable to atherosclerosis. Studies by Wang et al. [27] suggest that arterial degeneration begins early in postnatal life and is progressive in all human populations in which post-mortem studies have been performed. In 2 U.S.-based studies, for example, Stary [28] found 45% of infants to have aortic foam cells, whereas aortic lesions were observed in 100% of the aortas of 48 fetuses by D'Armiento et al. [29]. The environment of our life, the discovered and potentially undiscovered risk factors we are exposed to, determine the speed and extent that we develop atherosclerosis.

Genetically determined lifelong lipid levels are illustrative of the gene-environment interplay. Individuals with 2 defective low-density lipoprotein (LDL) receptor genes, homozygotes for familial hypercholesterolemia, are subject to a lifelong LDL in the range of >500 mg/dl. Left untreated, death from atherosclerosis typically occurs during childhood. The parents of a homozygote, obligate heterozygotes, will typically have an LDL roughly one-half that of their child, often dying of atherosclerosis in their 40s and 50s. Persons with favorable mutations, such as PSCK9142x and PCSK9579x, have genetically determined low PCSK9 levels and thus lifelong low LDL cholesterol levels, and have been shown to experience >80% fewer cardiac events than do those with more common alleles [30].

Although close examination of these 4 disparate cultures might yield traditional risk factors accounting for atherosclerosis, an equally plausible explanation is that risk factors for atherosclerosis exist that have not yet be to be discovered. It was not until 60 years ago that we became aware of any causative risk factors for atherosclerosis, so why would we necessarily have discovered all of them by the present time? Just as it is difficult to reckon with the prevalence of atherosclerosis in these ancient cultures, clinicians are not infrequently baffled when presented with a young person with newly diagnosed coronary artery disease with a dramatic dearth of traditional risk factors.

WHAT RISK FACTORS MIGHT HAVE EXISTED AMONG THESE ANCIENT PEOPLES? Inflammation

Without antimicrobials, infectious micro-organisms could not be effectively treated in ancient civilizations. Each of the 4 cultures studied by the Horus Team were located adjacent to a fresh water source such as the Nile or tributaries of the Colorado River. With insufficient knowledge of hygiene, water was likely contaminated with human waste and that of their livestock, if present. Such environments, together with crowded living conditions, would have fostered rampant acute microbial infections and enduring infestations with skin and gut parasites.

In 1974, an interdisciplinary team performed what may have been the most comprehensive multidisciplinary autopsy of a mummy [31—33]. The subject was Nakht, a teenage boy who worked as a weaver circa 1200 bce in Thebes (modern-day Luxor). Histologic and antigen immunoassay testing demonstrated that he harbored 4 different parasites: Schistosoma [34], Taenia species (tapeworm) [34], Trichinella spiralis [35], and Plasmodium falciparum (malaria) [31]. IfNakht is representative of the ancient Nile residents, these populations must have endured enormous, lifelong inflammatory burdens.

Though not found in the examination of Nakht, Mycobacterium tuberculosis was also common in ancient Thebes [36]. Mycobacterium tuberculosis was also detected in 2 of 12 Andean mummies circa 140 to 1200 ce [37]. Seven of the 12 carried other Mycobacterium sp. Salo et al. [38] reported the presence of Mycobacterium tuberculosis in a Peruvian mummy circa 1050 bce, and Corthals et al. [39], reported the presence of Mycobacterium sp. in an Inca mummy from Northwest Argentina circa 1600 bce.

The infectious burden of the current day Tsimane, an indigenous forager-horticulturalist culture living in the lowland forests and savannas east of the Andes in Bolivia, may be analogous to that experienced in ancient cultures given the Tsimane's subsistence lifestyle and infrequent access to modern medical care. Using 40- to 49-year-old men and women evaluated during an annual physical examination as an example, Gurven et al. [40] found that z70% and z20% were suffering from gastrointestinal or

respiratory symptoms suggestive of an infectious cause, respectively.

The systemic inflammation of chronic infections in these ancient peoples could well have accelerated the development of another inflammatory disease, that of atherosclerosis [41,42]. As long ago as the time of Czermak, Von Rokitanksy and Virchow described the pathophysi-ology of atherosclerosis as inflammatory (as reviewed in Gotto [43]). The inflammatory burden of chronically infected ancient persons may be analogous to the systemic inflammatory burden carried by contemporary patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), diseases punctuated by premature cardiovascular events. In an analysis of 263 clinic-based patients with established SLE, Esdaile et al. [44] found the risk-adjusted rate of nonfatal myocardial infarction, coronary heart disease death, and stroke over 8.6 years to be 10.1, 17, and 7.9 higher, respectively, than would be expected on the basis of traditional Framingham risk factors. In the Nurses' Health population-based study [45], those who developed SLE over a 28-year follow-up period, and thus would have had a milder form than those who had established SLE in the clinic-based study of Esdaile et al., had a 2- fold increase in the occurrence of cardiovascular events.

In a meta-analysis, Avina-Zuebiet et al. [46] found RA patients to have z50% increase in death from cardiovascular disease, even higher among those with more severe RA. In a related study, Stamatelopoulos et al. [47] found the frequency and severity of pre-clinical atherosclerosis to be equivalent between those with RA and those with diabetes. In another chronic inflammatory condition, Farrugia et al. [48] suggested the immune activation and inflammation of human immunodeficiency virus infection is pro-atherogenic and a chief cause for their increased incidence of cardiovascular events.

Distant past maternal stress from infection may also have played a role in the development of atherosclerosis in the offspring of mothers who suffered an infection during the gestation of the offspring. Shortly after Ruffer's tragic loss and before the Great War ended, the world endured a further challenge from the Great Influenza Pandemic, which caused frightening acute mortality, killing 500 million people worldwide (30-fold more deaths than attributed to the war itself). Importantly, the epidemic left a mark on the children exposed during gestation who remarkably had more heart disease 60 years later [49]. Records from the U.S. National Center for Health Statistics showed that the birth cohort of the first quarter of 1919 after the peak mortality experienced 25% excess ischemic heart disease prevalence relative to adjacent calendar quarters. We can thus conclude that transient maternal exposure to infection left a permanent imprint that promotes excess vascular pathology. This impact of a distant insult has been termed "cohort mortality" for the cohort who experienced the distant insult [42].

Finch proposed that inflammation be considered a core cause of human aging, citing its involvement not only

in atherosclerosis but also in the development of Alzheimer's, many types of cancers, and the basic aging process [41,42,50,51].

These findings raise the potential of a unifying hypothesis. Williams's antagonistic pleiotropic hypothesis suggests the potential of natural selection favoring genes that allow species to survive through the age of reproduction but that can be detrimental during post-reproductive life [52]. The need to survive chronic high-intensity exposures to infections during the z 4,000 generations of human evolution since the advent of Homo sapiens and the z 8,000 generations since the advent of the Homo genus could have selected for genes that provide a robust and effective inflammatory response. These same genes could have the opposite effect on survival during later life by promoting the acceleration of atherosclerosis and other diseases of aging [42,53].

Though inflammation per se is not currently regarded as a traditional coronary heart disease (CHD) risk factor, a belief in its importance is suggested by several clinical trials— CANTOS (Cardiovascular Risk Reduction Study [Reduction in Recurrent Major CV Disease Events]) [54] and SOLSTICE (A Study to Evaluate the Safety of 12 Weeks of Dosing With GW856553 and Its Effects on Inflammatory Markers, Infarct Size, and Cardiac Function in Subjects With Myocardial Infarction Without ST-Segment Elevation) [55]—now underway testing the suppression of various aspects of inflammation in the development of CHD.

Looking more broadly, Finch and Crimmins have proposed a general model of the impact of the environment on the aging process. They suggest that 3 groups of past or present factors be considered: 1) damage from infections, direct and indirect; 2) nutritional deficits; and 3) social stress. The pathways connecting each to pathophysiology are as of now incompletely defined but are thought to involve brain-immune-metabolic synergies beginning early in development and continuing throughout life (Fig. 2) [41,50,56].

Smoke inhalation. Indoor (domestic) smoke is a candidate for a pro-atherogenic inflammagen that was likely to have been prevalent in many ancient cultures. The 4 cultures the Horus Team studied all cooked over open fires with Egyptians using wood and coal; the Peruvians using wood or dung; the Ancestral Puebloans using wood; and the Aleutian Islanders using seal oil and wood [1]. A home often filled with smoke would have been especially common among the Aleutian Islanders. They lived in subterranean home structures in which fire was used internally for heating, lighting, and cooking using driftwood and marine mammal oils. The only access for ingress, egress, and ventilation was through 1 of several openings in the roof using a ladder made from a single log into which steps were cut (Fig. 3A) [57—59]. Similarly, the Native American Ancestral Puebloans living along the Colorado River also lived in subterranean homes using the same chimney model of ingress and egress. Their homes too were lit by the light of an indoor fire (Fig. 3B).

Infection Inflammagens

Brain-immune-metabolism Inflammation Atherosclerosis Cancer

Diet Social stress

FIGURE 2. Finch and Crimmins's proposed general model of the environmental impact on the aging (adapted from Finch [42]). Infections and inflammagen (noninfectious inhaled or ingested particles such as tobacco, fossil fuel, dust, and endotoxins), nutritional deficits, and social stress each result in alterations of the immune system, brain, and metabolism that can result in inflammation, atherosclerosis, and cancer. The process begins early in development and continues throughout life.

The presence of pulmonary anthracosis of soot inhalation discovered by Zimmerman in the autopsy of 2 Aleutian Islanders is consistent with such an exposure [19,20]. Ancient Egyptian mummies have also been found to have anthracosis [13,60,61].

The earliest human evidence of domestic smoke inhalation comes from the sooty deposits suggestive of anthracosis on the inner surface of ribs in burials from the city of Catalhoyuk 8,500 years ago in southern Turkey [41,62,63]. Also relevant to Peruvians is the recent suggestion of the use of tobacco in the region, as determined by the presence of nicotine in the hair of mummies from northern Chile [64]. By abundant evidence, cigarette smoke is atherogenic, and even secondhand (passive smoke exposure) increases the risk of arterial calcification [65,66]. Passive cigarette smoke exposure may serve as a model for domestic smoke exposure. Anthracosis due to household smoke (domestically acquired particulate lung disease, also called "hut lung disease") is well documented in case reports [67,68]. Rodent models show responses to wood smoke that are pro-atherogenic, such as gelatinase and methane mono-oxygenase activity in aortas after hardwood smoke exposure [69,70].

Yet-to-be discovered risk factors. We are limited in our assessment of other potential causes of atherosclerosis by what we can measure and thus subject to testing. After serum cholesterol could be measured, Carl Muller [71] could correlate cholesterol levels with CHD in a group of heterozygous familial hypercholesterolemia patients in the 1930s. A decade later, the work of Cohn et al. [72], Gofman et al. [73], and others [43] paved the way for low-and high-density lipoprotein cholesterol levels to be positively and negatively correlated with CHD, respectively. Three decades later, an assay for high-sensitivity C-reactive protein was developed, following which it could be

FIGURE 3. Drawings of a barabara and a subterranean pit house. (A) Drawing by John Webber of an Aleutian Island barabara, the typical subterranean dwelling of the Aleutian Islanders. Drawn during Captain James Cook's third around-the-world voyage in 1778 [59]. (B) Drawing of a subterranean pit house, the typical dwelling of the Ancient Puebloans of the American Southwest. Image from the Lost City Museum, Overton, Nevada.

FIGURE 4. The weighing of the heart ceremony, the judgment day of the ancient Egyptian religion. The heart of the deceased is weighed against the Feather of Ma'at, the goddess of truth and justice [86]. In the Papyrus of Ani circa 1200 bce (public domain), via Wikimedia Commons.

correlated with atherosclerosis [74]. Multiple potential serum correlates with CHD are currently under active investigation. To believe that other measures will not be discovered and found to be correlative and potentially causal for atherosclerosis would seem to be presumptuous. Likely, there is much to be learned.

GENETIC CONTRIBUTION

Robert Roberts and Alex Stewart [75] suggested that genetic predisposition accounts for 40% to 60% of human susceptibility to coronary artery disease and thus to atherosclerosis. Genomewide association studies have discovered an increasing number of individual single nucleotide polymorphisms (SNP) risk variants that make up this predisposition [76]. The risk associated with each SNP has generally been modest, but the frequency and number of SNP make their contribution substantial [77]. Bos et al. [78] have correlated a number of these SNPs to multivessel bed calcification. In this issue, Zink et al. [79] further explore the current contribution of genetics to atherosclerotic susceptibility and its potential evolutionary changes.

Interestingly, apes and humans share 99% of their genes, yet the lifespan of an ape is one-half that of a modern human (as reviewed in Finch [42]). Among the 1% of differing genes, could many be inflammation-promoting genes favorable to natural selection?

SUMMARY

Autopsy studies performed as long ago as 1852 are consistent with current-day CT scans, demonstrating the surprising result that atherosclerosis was common among 4 diverse ancient cultures. Potential causes include frequent and chronic infections resulting in chronic inflammation, smoke inhalation, or other as yet undiscovered risk factors. A synthesis of these findings is consistent with a geneenvironment interplay as causal for atherosclerosis. As humans, our genes result in our susceptibility, our environment and the choices we make within it, determine its speed and severity.

POSTSCRIPT Ruffer's heroic death

Toward what would become the end of the Great World War, Ruffer was dispatched as commissioner of the British Red Cross Society of Egypt to the Greek city of Salonika (called Thessaloniki in Greek) to help with the reorganization of country's sanitary service [80,81]. The mission required a perilous round trip voyage across the Mediterranean Sea during the time of the German submarine blockade. On departing for Salonika in 1916, the same year he received his knighthood, his wife Alice recounted, "When starting in December 1916, on a mission which was evidently attended by dangers ... he left with me instructions as to the various unfinished papers at which he and I had

worked together," which included a posthumously published monograph [82,83]. Sadly this premonition proved all too true. On April 15, 1917, the second night of his voyage home on the HM Transport Arcadian, a torpedo from the German submarine UC74 commanded by Wilhelm Marschall sank the ship [81,83,84]. Of the = 1,000 people on board, 279 perished from the explosion or by drowning. Ruffer was among the latter group. Four years later, a former classmate of Ruffer's at Oxford, A. J. Butler, learned that Ruffer had provided the life vest he was wearing following the explosion to a hospital nurse on board who was without one. Ruffer went down with the ship and was not rescued. The nurse ended up caring for a friend of Butler's in Belfast, who recalled the story to Butler for posterity [85]. Ruffer's ultimate act of chivalry was performed 5 years and 2 days following the sinking of the Titanic.

Heaven in ancient Egypt: the Field of Reeds

Medicine has been the beneficiary of the decision by ancient people to artificially mummify their dead. Practicing this art for 2 millennia, the Egyptians were particularly adept at the craft. This was not accidental. Mummification was a process associated with their religious belief in an afterlife, called the Field of Reeds, a place of bliss with plentiful food and harvests. In their religious ideology, it was necessary for the Ka (a version of the soul) to periodically return to the body on Earth for sustenance. In order for the Ka to return to and recognize the body, careful preservation was required, hence the 70-day embalming process by the specially trained priests who were expert in the use of dehydrating salts and knew which prayers and rituals were required by each step in the process [86].

A judgment day followed death in this religion dating back to at least 1500 bce. In the weighing of the heart ceremony, the heart of the deceased was weighed against a feather, the Feather of Ma'at, the goddess of truth and justice (Fig. 4). If the deceased had lived a life of truth and integrity, their heart would be as light as the feather, securing their access to the Field of Dreams. Should the heart of the deceased prove to be heavy with wrongdoing, it would immediately be devoured by Ammut, the monster resting under the balance, and the hope of an afterlife lost forever. Written spells lined the walls of the sarcophagus meant to instruct the heart to provide a story that would ensure a successful rise to the Field of Reeds [86].

REFERENCES

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