Wednesday 26 December 2012

Signs of malnutrition in a 1.5 million year old child's skull from the Olduvai Gorge.

The Olduvai Gorge is a ravine in the Great Rift Valley in northern Tanzania, which has produced numerous fossil and sub-fossil remains of early Humans and Hominins (anything more closely related to Humans than to Chimpanzees) dating from about 1.9 million years ago till around 17 000 years ago, and is considered to be one of the most important palaeoarchaeological sites known by those studying early Human evolution.

In a paper published in the journal PLoS One on 2 October 2012, a team of scientists led by Manuel Domínguez-Rodrigo of the Instituto de Evolución en África at the Museo de los Orígenes and the Department of Prehistory at Complutense University, both in Madrid, discuss the discovery of a partial skull of an infant in the Olduvai Gorge from about 1.5 million years ago, which shows signs of having died of a malnutrition related illness. Due to the fragmentary nature of the material it was not possible to tell the exact species of the individual.

Ectocranial (top right) and endocranial (top left) close-up views of the fossil, accompanied by magnifications of theporotic hyperostosis paleopathology as observed ectocranially (lower left) and edge-on at the diploic-table junction (lower right). Scale bars = 1 mm. Domínguez-Rodrigo et al. (2012)

The skull fragments come from an infant with an estimated age of about two years, suffering from a condition called porotic hyperostosis, a pathology associated with anemia. In porotic hyperostosis there is extensive marrow overgrowth within the skull bones, leading the flat outer layers of the bone to become thin and soft.

Scurvy and rickets can cause similar thinning of the skull, but scurvy causes only thinning of the outer bones without modification of the marrow chambers, whereas rickets can cause some enlargement to the marrow chambers, but not to the extent seen in the Olduvai fossil. Inflammatory diseases and infections can cause similar damage, but typically show several layers of damage and regrowth as the body fights the infection.

Iron-deficiency anemia is known to cause porotic hyperostosis, but not to the severe extent seen in this individual. Instead Domínguez-Rodrigo et al. suggest the infant was suffering from B₁₂ (cobalamin) and B₉ (folic acid) vitamin deficiencies. This suggests that malnutrition set in while the infant was still breast-feeding, probably due to a deficiency of meat in the mother's diet (modern humans, with sophisticated agriculture and wide trading networks can survive happily on vegetarian or even vegan diets, but hunter-gatherers in most climates usually need to rely on meat to obtain their full vitamin complement for at least part of the year.

A series of scanned sections through the skull, revealing the extent of the pathology. Domínguez-Rodrigo et al. (2012)

See also Skull closure in the Taung InfantThe earliest evidence of fire use from million year old sediments in Wonderwerk Cave, Northern Cape Province? The canine teeth of Australopithecus anamensisAnother look at the Canteen Kopje Skull and A re-evaluation of the Iwo Eleru skull.

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