All remaining sections of the book assume that readers are familiar with the methodology outlined in Part II. Much of what followswill be unintelligible without an understanding of basic skeletal indicators of nutrition and disease. In particular, we suppose that all who venture forward comprehend our measures of childhood stress, which are average stature (a measure of a society's history of net nutrition in childhood), linear enamel hypoplasias (somewhat like tree rings, but in teeth), and anemia (porotic hyperostosis and cribra orbitalia, which are identified by pitting of the skull or eye orbits, respectively). We also take for granted a familiarity with our measures of health deterioration that accompany aging, including dental decay and degenerative joint disease. Infections that penetrate the bone and trauma, such as broken bones or weapon wounds, can occur at any age but are most frequent among adults.

To facilitate comparisons, the seven component measures of health have been scored on a scale of 0 (lowest or worst) to 100 (highest or best). These scores are then averaged or weighted equally to form ourMark I version of the health index. Bear in mind that the index and its components have been adjusted for variations in the age distributions of deaths across sites.