Porotic hyperostosis, is a

pathological Pathology is the study of the causal, causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when us ...

condition that affects bones of the

cranial vault The cranial vault is the space in the skull within the neurocranium, occupied by the brain. Development In humans, the cranial vault is imperfectly composed in newborns, to allow the large human head to pass through the birth canal. During bir ...

, and is characterized by localized areas of spongy or porous

bone A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...

tissue.El-Najjar M and Robertson Jr AL. 1976
Spongy bones in prehistoric MARICOTAS.
''Science'' Volume 193, Issue 4248, Pages 141-143. Retrieved on July 9, 2007. The

diploë Diploë ( or ) is the spongy cancellous bone separating the inner and outer layers of the cortical bone of the skull. In the cranial bones, the layers of compact cortical tissue are familiarly known as the tables of the skull; the outer one is ...

, or spongy tissue within the bones of the cranium, swells and the tissue of the outer surface becomes thinner and more porous in appearance.Angel JL. 1966.
Porotic Hyperostosis, Anemias, Malarias, and Marshes in the Prehistoric Eastern Mediterranean.
''Science'' Volume 153, Number 3737, Pages 760-763. Retrieved on July 9, 2007.Cule J and Evans IL. 1968
Porotic hyperostosis and the Gelligaer skull
''Journal of Clinical Pathology'', Volume 21, Issue 6, Pages 753–758. Retrieved on July 9, 2007. This condition was widely accepted as a result of

anemia Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, th ...

, which is typically due to an iron deficient diet,Stuart-Macadam P. 1992 Porotic hyperostosis: a new perspective. ''American Journal of Physical Anthropology''. Volume 87, Issue 1, Pages 39-47. . Retrieved on July 9, 2007. but several lines of evidence suggest that the accelerated loss and compensatory over-production of

red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

s seen in

hemolytic Hemolysis or haemolysis (), also known by several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo o ...

and

megaloblastic anemia Megaloblastic anemia is a type of macrocytic anemia. An anemia is a red blood cell defect that can lead to an undersupply of oxygen. Megaloblastic anemia results from inhibition of DNA replication, DNA synthesis during red blood cell production. ...

are the most likely proximate causes of porotic hyperostosis.Walker PL ''et al'' (2009) The causes of porotic hyperostosis and cribra orbitalia: a reappraisal of the iron-deficiency-anemia hypothesis. ''Am J Phys Anthropol'' 139(2):109-125 In

anthropology Anthropology is the scientific study of humanity, concerned with human behavior, human biology, cultures, societies, and linguistics, in both the present and past, including past human species. Social anthropology studies patterns of behavi ...

, the presence of the condition has been considered evidence that a past population suffered chronic or episodic malnutrition. Anthropologists examine bones of past populations to learn about their lifestyles. A sub-discipline known as paleonutrition has focused on the presence of porotic hyperostosis, among other nutritional disorders. A high incidence of the disease indicates the population adapted poorly to its environment or was under nutritional stress. A low level of

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

in the blood is also a defense against

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

s, so a high incidence of the disease in a population could also indicate an attempt to fight off an infectious disease. From this perspective, porotic hyperostosis could be viewed as a biological attempt to adapt to the environment, rather than an indicator of malnutrition.{{citation needed, date=December 2015

References

Skeletal disorders