only an indirect relationship to the duration of the stressor. Studies of dental enamel hypoplasia are used to study child health. Unlike bone, teeth are not remodeled, so they can provide a more reliable indicator of past health events as long as the enamel remains intact. Dental hypoplasias provide an indicator of health status during the time in childhood when the enamel of the tooth crown is being formed. Not all of the enamel layers are visible on the surface of the tooth because enamel layers that are formed early in crown development are buried by later layers. Hypoplasias on this part of the tooth do not show on the surface of the tooth. Because of this buried enamel, teeth record stressors form a few months after the start of the event. The proportion of enamel crown formation time represented by this buried in enamel varies from up to 50 percent in molars to 15-20 percent in anterior teeth. Surface hypoplasias record stressors occurring from about one to seven years, or up to 13 years if the third molar is included. Skeletal non-specific stress indicators Porotic hyperostosis/cribra orbitalia It was long assumed that iron deficiency anemia has marked effects on the flat bones of the cranium of infants and young children. That as the body attempts to compensate for low iron levels by increasing red blood cell production in the young, sieve-like lesions develop in the cranial vaults (termed porotic hyperostosis) and/or the orbits (termed cribra orbitalia). This bone is spongy and soft. It is however, highly unlikely that iron deficiency anemia is a cause of either porotic hyperostosis or cribra orbitalia. These are more likely the result of vascular activity in these areas and are unlikely to be pathological. The development of cribra orbitalia and porotic hyperostosis could also be attributed to other causes besides an iron deficiency in the diet, such as nutrients lost to intestinal parasites. However, dietary deficiencies are the most probable cause. Anemia incidence may be a result of inequalities within society, and/or indicative of different work patterns and activities among different groups within society. A study of iron-deficiency among early Mongolian nomads showed that although overall rates of cribra orbitalia declined from 28.7 percent (27.8 percent of the total female population, 28.4 percent of the total male population, 75 percent of the total juvenile population) during the Bronze and Iron Ages, to 15.5 percent