Porotic hyperostosis

Porotic hyperostosis, also known as osteoporosis symmetrica, is a disease that causes bone tissue to appear spongy

and become soft. In the disease, the spongy marrow within the bones of the skull becomes overgrown.

The overgrowth of the skull's marrow may cause the outer table of the bones to move and become thinner. It is widely accepted that the disease is related anemia, probably due to an iron deficiency. Frequently, the cause of the anemia is thought to be malnutrition. One study found that in precolumbian populations in the American Southwest, populations with diets rich in iron had a much lower incidence of porotic hyperostosis than did those with diets poor in iron.

In anthropology, presence of the condition is used by researchers to detect malnourished populations. Anthropologists can look at bones of people from ancient populations and learn about their diets and lifestyles. A high incidence of the disease indicates that the population adapted poorly to its environment or was under nutritional stress. A low level of iron in the blood is also a defense against pathogens, so a high incidence of the disease in a population could also indicate an attempt to fight off a microorganism.