Anthropologists often obtain data on health, disease, and death from ancient populations using the methods of paleopathology, the study of ancient disease. Paleopathology not only gives us a glimpse into conditions in ancient populations. It also contributes to our evolutionary perspective of disease. By looking at populations in different environments over time, we may be able to gain insights into the long-term relationships of human biology, culture, and disease. An example of the use of paleopathology is to document changing patterns of disease and health that took place during the transition from hunting and gathering to agriculture during human history.
The primary source of paleopathological information is skeletal remains. Inspection of bones is augmented with X-rays, chemical analysis and other laboratory methods. Such studies can tell us something of an individual's history of health and disease, and often the age and cause of death. Diseases such as osteoarthritis may affect bones directly. Other diseases such as syphilis and tuberculosis may leave indications of their effects on the skeletal system. Physical traumas due to injuries or violence often leave detectable fractures. Signs of healing or infection tell of the long-term effects of such traumas. The next section will discuss some of the implications of paleopathology in recent human history.
I. THE EVIDENCE OF PREHISTORIC SKELETONS
A number of techniques are used to evaluate nutrition. Both skeletal and dental changes are noted.
(1) Wear on teeth and analysis of dental caries. High rates of dental caries are invariably associated with soft, sticky foods as with agricultural diets. The rate of wear and incidence of decay go up with the adoption of agriculture. The rate of wear in many agricultural people is often a result of grit from grinding stones.
(2) Iron deficiency causes anemia. When prolonged, perotic hyperostosis occurs--a distinctive porosity seen in the cranial vault or the eye sockets. The anemia itself can be caused by parasites or a variety of infections.
(3) Vitamin D deficiency causes legs to grow bent.
(4) Malnutrition or under-nutrition is inferred from skeletal measurements. A decline of stature of historic populations has been used to indicate nutritional status. Deciduous teeth in particular seem to be sensitive to nutrition.
(5) Certain infections leave specific traces in the skeleton. Tuberculosis leaves characteristic traces on the ribs and tends to destroy the bodies of the lumbar vertebrae. Infections from the treponema spirochete in yaws or syphilis can produce either local or widespread skeletal damage. When syphilis is congenital, it can leave the characteristic 'Hutchinson's incisor' defect. Leprosy is characterized by damage to the bones of the face, fingers, and toes.
(6) Various cancers are identifiable in the skeleton. Primary bone cancer is rare, but the skeleton is a common site for the secondary spread of cancerous growth from other tissues. Studies of rates of bone cancers in prehistoric populations suggest that they are extremely rare--even when the relative scarcity of elderly people is taken into account.
(7) Trauma in skeletons is clearly evident in bone fractures, especially when they have not healed successfully. It is often possible to distinguish between traumas resulting from a fall and a blow such as sustained in violence. Studies of Neandertal skeletons reveals that the pattern of fractures correlates well with those seen in contemporary rodeo riders. This implies close contact "of the dangerous kind" with large animals.
(8) The individual workload leaves traces in the skeleton. High rates of physical labor can appear as degenerative joint disease. Muscular development results in increasing size of muscle attachment areas on bone. Women who spend a lot of time grinding corn develop deltoid tuberosities similar to those that develop among modern bodybuilders.
(9) Growth-disrupting and growth-retarding stresses during childhood will leave transverse lines of dense bone visible in radiographs of long bones of the body. These are the so-called Harris lines. The formation of tooth enamel is also vulnerable to stress. When those are grossly visible to the naked eye, they are known as enamel hypoplasias. When visible only as lines in microscopic cross sections they are known as Wilson bands. Markers such as hypoplasia, Wilson bands, and Harris lines can be produced in the skeleton by a variety of stressors, including starvation, severe malnutrition and severe infection.
(10) The age of an individual at death can be determined based on the development and eruption of teeth (both deciduous and permanent) providing a fairly precise indicator of age up to fifteen years. Adult ages are harder to determine, since environment can also influence the rate of degeneration. Signs of degeneration include patterns of wear and other changes to the teeth; changes in the sutures of the skull bones, changes in the articular surfaces of the pelvis and changes in the microscopic structure of bone.
II. HEALTH CHANGES SINCE THE UPPER PALEOLITHIC
This change marked the extinction of large game animals and the subsequent adoption of foraging patterns aimed at a wider array of small animals, seeds, and aquatic foods. Adult stature for both sexes seemed to have declined during the Mesolithic by about two inches. Hypoplasia rates of teeth were higher, suggesting more biological stress.
B. The health of foragers compared to subsequent farmers. Most of the comparisons are based on natural cemetery populations of 50 to 200 individuals. The conclusions about trauma are interesting: the food foraging life isn't particularly violent in the Hobbesian model--nor is it as serene as portrayed currently in college cultural anthropology textbooks.
Signs of infection seem to increase as settlements increase in size and permanence. In Illinois at Dickson Mounds, the signs of infection doubled with adoption to maize agriculture. Farmers appear to have been less well nourished than the earlier foragers. The size, stature, and robustness of adult individuals declined with the adoption of farming. In some regions, domestication of animals reversed the long term decline in nutrition. Enamel hypoplasia suggests that nutritional stresses became more frequent and more severe as farming replaced foraging in different parts of the world. Data also suggests that the adult ages at death amongst foragers were greater (older) than those of the subsequent early farmers.
The later intensification of agriculture appears to have had mixed results. Some populations clearly rebounded to pre farming levels. Others did not rebound. Bronze Age royalty enjoyed better health than commoners. Enamel hypoplasia rates increased, suggesting density-dependent (crowd) diseases.
The extremely high levels of stress among the less privileged citizens of complex societies are not restricted to antiquity. Rates of malnutrition, infection, and death among American Black populations in the 1920s in the United States equal or exceed those of most prehistoric groups.
Most reconstructions of the history of the human species suggest that the total human foraging population grew very slowly prior to the adoption of farming. The population grew very rapidly thereafter.
There are several possible explanations about why populations grew slowly before agriculture. They may have grown slowly, not just because their technology was primitive, but that their natural world might have presented a very challenging existence to them. Women may have begun having children later in their teenage years. Periodic declines in nutrition, chronic disease or hard work may have reduced fertility. Prolonged breast feeding along with the postpartum taboo witnessed in many contemporary societies may have 'naturally' maintained the birth space at five years.
Village life led to a shorter birth space. Children were weaned earlier. The food base became narrower with dependence on a few or even a single crop, which for many caused vitamin deficiencies. Maize, for example is deficient in niacin. This was compensated for in many cultures by either treating the corn with ash to release more niacin or to supplement the diet with beans which provided the lacking vitamin. Potato, the mainstay of many Irish up to the Great Potato Famine is deficient in vitamin A. This can be made up by a supplement of buttermilk or vegetable greens.
The modern knowledge of nutrition, the variety of foods available, transportation, sanitation, and refrigeration contribute to the secular growth trend well documented in the last two centuries. In recent time there has been a consistent trend of faster growth, earlier maturity, and greater stature. We document these trends in our unit on human growth.
(My note: this is an extremely brief treatment of a complex topic. Several of the references are well worth your time, if just only for the truly remarkable photographs!)
..... CJ '99
Augderheide, A. and Rodriguez-Martin, C. eds. Cambridge Encyclopedia of Human Paleopathology New York: Cambridge University Press, 1998.
Bowers and Bell, eds. Manual of Forensic Odontology . Ontario: Manticore Publishers,1997.
Cohen, M. Health and the Rise of Civilization. New Haven:Yale University Press, 1989.
Haglund and Sorg, eds. Forensic Taphonomy. Boca Raton: CRC Press, 1997.
Larsen, C. Bioarchaeology New York: Cambridge University Press, 1997.
Ortner and Putschar Identification of Pathological Conditions in Human Skeletal Remains.Washington: Smithsonian Institution Press, 1985.
Pickering and Bachman The Use of Forensic Anthropology. Boca Raton: CRC Press, 1997.
Relethford, J. The Human Species, 3rd ed. Mountain View: Mayfield Publishing Company, 1996.
Roberts, C. and Manchester, K. The Archaeology of Disease Ithica: Cornell University Press, 1995.