MEDIO SOCIOECONÓMICO

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Paleopathology, the study of disease in ancient remains, is aimed at improving our understanding of the evolution of diseases and their interaction with human biologic and social history (Aufderheide & Rodriguez-Martin, 1998; Brothwell & Sandison, 1967; Ortner & Aufderheide, 1991). Pathogenic organisms, environmental factors, and patterns of disease evolve just as do larger organisms, including hosts and vectors of disease. There is evidence, however, for considerable stability in some host–parasite relationships. Similar parasitic worms have been found in Egyptian mummies and modern Egyptians. Such histori- cal perspectives are necessary to prepare us for changes in disease incidence and for new diseases, such as Legionnaire’s disease and AIDS (Zimmerman, 2001).

Evidence of ancient disease is obtained from historic records, works of art such as paintings, pottery effigies, and figurines, religious statuary, figures and faces on coins, skeletons, and mummies. Many diseases leave lit- tle or no direct mark on the bones and pseudopathologic changes can be produced by erosive forces or animals chewing on bones. Although lesions in archeological specimens represent only a small proportion of the total morbidity, the incidence of disease of a population, there are valid reasons for such studies. Certain characteristics or anomalies are useful as genetic markers. Evidence of traumatic injuries can give information on the occupa- tional or military orientation of the group under study. Infectious diseases provide inferences on the general health status of the population.

A major consideration in dealing with ancient mate- rial is that modern patients with skeletal pathology pres- ent one with symptoms and signs, whereas archeological material presents one with a bone that has either a hole or a bump. The diagnosis of skeletal lesions is properly based on history, radiological findings, and pathology, but we rarely have adequate history in dealing with ancient skeletal material, and pathology is generally con- fined to the gross appearance, as microscopy is highly technical (Schultz, 2001). One other caution is the para- dox that skeletons showing pathology are usually those of relatively healthy individuals. Unhealthy individuals die very quickly, before they have time to develop skeletal lesions.

Mummies are bodies preserved either artificially or naturally. The Egyptian practice of artificial mummifica- tion developed from the natural preservation of bodies buried in the desert in pre-Dynastic times, which may have had a role in the development of the belief in life after death. When it became customary to provide the deceased with food and funerary furniture, larger graves and above- ground tombs allowed decomposition, necessitating the development of artificial techniques of mummification. All deceased Egyptians were mummified until the Christian era, ca. 200–400 AD, with a gradual refinement of technique over the millennia, although in all periods the poor were less carefully mummified (Zimmerman & Angel, 1986). Artificially preserved mummies are found in many other areas of the world as well.

Natural mummies, due to freezing or drying, have been found in bogs and in arctic and arid areas.

These bodies, both human and animal, often show excellent preservation (Spindler, Wilfing, Rastbichler, et al., 1996).

The rehydrated tissues of mummies subjected to autopsy examination result in the diagnosis of many con- ditions with a considerable degree of confidence and accuracy (Cockburn & Cockburn, 1998). Mummified tissues and bones are studied by light and electron microscopy, chemical analyses, and paleoserology. Microbiological studies have not been useful, as viable pathogens have not been cultured from paleopathologic material, although organisms can be identified histologi- cally, including viruses, using electron microscopy.

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After an early 19th-century period focusing on the exam- ination of native American skulls, interest shifted to evi- dence of disease, dominated by activities at the Smithsonian Institution, the Army Medical Museum, and the Peabody Museum at Harvard. In Europe a contro- versy arose when Rudolf Virchow, the German patholo- gist, anthropologist, and politician questioned the authenticity of the Neander Valley specimen, suggesting that the Neanderthal remains were those of an abnormal modern man suffering from rickets or syphilis.

The next period, from 1900 to 1970, began with the Smithsonian appointment of Ales Hrdlicka. Describing lesions that he called “symmetrical osteoporosis,” he noted that they were probably representative of a systemic disorder. He built one of the world’s great collections and contributed to the training of many anthropologists. Flinders Petrie examined prehistoric Egyptian bones by X-ray in 1897, but the technique was little used until the work of Roy Moodie in the 1930s, and is only now begin- ning to be fully utilized.

The first of the truly modern paleopathologists was Sir Marc Armand Ruffer. Ruffer was an English experimental pathologist and bacteriologist of some note when an illness forced him to Egypt for recupera- tion. He developed the rehydration technique that is still in use for preparing microscopic sections of mum- mies and made a number of important diagnostic contri- butions before being lost at sea in World War I (Ruffer, 1921).

The first full-length book on paleopathology was written by Roy L. Moodie (1923), an American

anatomist. His book covers humans, lower vertebrates, plants, etc. and contains many errors, mostly related to the theories of the early 20thcentury. Moodie also edited Ruffer’s collected papers and published other books and papers in the field.

Paleopathology was revitalized in the 1970s by the activities of three groups. The Paleopathology Association was founded in Detroit by Aidan and Eve Cockburn and 12 charter members. The association pub- lishes a quarterly newsletter and has studied a number of mummies. These studies have gone far toward improving the difficulties that were experienced in interpreting lesions in the past, and a wide variety of new techniques have come into play. These include more sophisticated radiographic studies such as computed tomographic scanning, electron and scanning electron microscopy, flu- orescent antibody and other serologic techniques, neutron activation analysis, and other chemical and microbiolog- ical techniques.

A second group, headed by Marvin Allison and Enrique Gerszten at the Medical College of Virginia, Richmond, has conducted an extensive survey of Peruvian and Chilean mummies.

A seminar in paleopathology was held at the Smithsonian Institution from 1971 to 1974. This full- length course provided a continuing major impetus in paleopathology. As world-wide interest in the field increases, with much research being conducted in Europe, South America, and Australia, the number of journals accepting paleopathology articles also is increasing, as summarized by the Bibliography of Paleopathology published by the San Diego Museum of Man (Tyson, 1997).

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The preservation of buried bone varies with soil type. Bones from acidic soil areas, such as Mesoamerica, will be softened and often in poor condition. Careful excava- tion of skeletons, with complete clearing of the soil, is essential. Most bones can be cleaned with warm water. Skulls should be examined first for remnants of brain tissue and for ear ossicles.

Hot paraffin wax, formerly used for conservation of bone, can be damaging. Shellac preserves the surface but tends to peel off in a few years, taking bone with it. Soluble plastics are the best preservatives. Plaster of Paris

is good for support but difficult to remove from bones (Brothwell, 1972).

Examination of mummified remains depends on rehydration of the tissues. Ruffer’s rehydrating solution, still in use today, is 50 parts water, 30 parts absolute alco- hol, and 20 parts 5% sodium carbonate solution, most easily prepared by dissolving 0.6 gm of sodium carbonate in 42 ml of water and adding 18 ml of absolute (100%) alcohol. Allison simplified Ruffer’s technique by immers- ing the tissue in Ruffer’s solution until fully rehydrated to visual inspection (usually 24–48 hr). The tissue is then fixed in alcohol and processed. If the tissues dissolve in the solution it is because they are completely contami- nated by bacteria. The solution always develops a dark brown turbidity (Zimmerman & Kelley, 1982).

A variety of special stains can be used to demon- strate specific features of the tissues. In general, connec- tive tissues and any foreign elements, such as pigments, bacteria, or parasites are best preserved, while epithelial tissues fare less well. Thus the connective tissues stains are those used most. The standard hematoxylin and eosin is useful only in a very general sense. Other techniques that have been applied to rehydrated tissue include plas- tic embedding of bone specimens and scanning and transmission electron microscopy.

Dating of biological materials, human or non- human, is often of importance in dating an archeological site, either independently or in correlation with conven- tional archeological techniques such as the evaluation of pottery, hieroglyphic texts or other artifacts, or historical records. In paleopathology, dating is essential in provid- ing an historical context for the evaluation of disease processes detected. Radiocarbon dating is the “gold stan- dard,” but a variety of other techniques are applicable. These include amino acid racemization, which is temper- ature dependent, electron spin resonance, and ancillary techniques such as dendrochronology, mummification styles, and tattoos (Zimmerman & Angel, 1986).

Age determination is another important facet of the study of human remains, allowing the construction of population profiles and the development of a paleoepi- demiologic approach. At the individual level, many dis- eases occur in specific age ranges and age determination can be a critical factor in differential diagnosis, particu- larly with regard to bone diseases. In contrast to dating, no single aging technique is best. Techniques used include gross evaluation of the skeleton and viscera, hand–wrist radiographs, bone histology, dental changes,

and, in special cases, amino acid racemization (Zimmerman & Angel, 1986).

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Cells continuously adapt to internal and environmental stimuli and stresses. If the cell is no longer able to adapt, then cell injury results, either reversible or leading to cell death, necrosis.

Injury that cannot be limited at the cellular level calls forth an inflammatory response. If the stimulus is terminated, then the acute reaction subsides and there is usually healing and regeneration of the tissue, although specialized tissue such as the brain is replaced by scar tissue. If stimulus and inflammation continue, then a chronic phase follows. Regeneration and repair are attempted, with scarring the almost inevitable result.

Special types of inflammation include allergic inflammation, granulomatous inflammation (tuberculosis or foreign body reactions), ulceration (the loss of the lining or surface of an organ), and abscess formation (accumulation of pus in solid tissues).

These cellular and tissue reactions to stresses and stimuli result in a wide variety of disease states, falling into the following broad categories: congenital defects, trauma, infectious disease, metabolic and nutritional disease, degenerative disease, immunologic disease, circulatory disorders, and neoplastic disease.

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Congenital Defects

These defects, which are present at birth, may be heredi- tary or acquired before birth. Many are minimal and do not cause any functional disability. There can be abnormal fusions of bones, or failure of bone components to fuse. Skull sutures may vary in their relationship. Statistical analysis of skeletal variations can reveal signif- icant associations and inferences as to the biological affini- ties of the individuals under study. Examples of acquired congenital disorders are infections such as German measles and syphilis, and chemically induced abnormali- ties such as the thalidomide babies born in the 1950s.

Congenital dwarfism is a generalized condition that is easily recognized. Achrondoplasia, the most common form, is due to a hereditary defect in the formation of

enchondral bone, that is bone formed first as cartilage. There is shortening of the bones of the extremities and the mandible and forehead appear prominent. The long bones are relatively thick and the head is larger than normal, with a prominent frontal region, small face, and depres- sion of the bridge of the nose. The legs and spine are curved as well.

This condition is of great antiquity and wide geo- graphic distribution, with skeletal remains from the pre- Columbian New World and documentation in ancient Egypt from pre-Dynastic times up to the 30th Dynasty by skeletons, wall paintings in tombs, figurines, and statues. The ancient word for an achondroplastic dwarf was

nemew and they held various offices, as these dwarves are

generally of high intelligence. Very accurate depictions show them in charge of jewelry or pets or in personal attendance on their masters, often acting as jesters. Several of these dwarves must have been persons of considerable wealth and importance, being found in elab- orate and costly tombs. There was also a magical signif- icance, accounting for the figurines and amulets, associated with spells to facilitate birth.

Other examples of congenital disease include: hydro- cephaly from Roman Britain, Egypt, and Neolithic Germany; a case of Down’s Syndrome in a 15th century AD

Inuit child mummy from Greenland (Hart Hansen, 1998); alpha-l-antitrypsin (AlAT) deficiency and emphysema in another Inuit child, from 10th century AD Alaska (Zimmerman, Jensen, & Sheehan, 2000); and spina bifida, a failure of closure of the sacrum, in Egyptian mummies.