Most Ancient Case of Tuberculosis Found In 500,000-Year-Old Human
Evidence Suggests Vitamin D Deficiency Endangers Migrating Populations
Although most scientists believe tuberculosis emerged only several thousand years ago, new research from The University of Texas at Austin reveals the most ancient evidence of the disease has been found in a 500,000-year-old human fossil from Turkey.
The discovery of the new specimen of the human species, Homo erectus, suggests support for the theory that dark-skinned people who migrate northward from low, tropical latitudes produce less vitamin D, which can adversely affect the immune system as well as the skeleton.
Professor John Kappelman of The University of Texas at Austin holds a plaster cast replica of the cranium of the newly discovered young male Homo erectus specimen from western Turkey. The fossil is 500,000 years old and was recovered from a block of travertine stone as it was being sawed into tiles for the building stone market.
Prior to this discovery in western Turkey, which helps scientists fill a temporal and geographical gap in human evolution, the oldest evidence of tuberculosis in humans was found in mummies from Egypt and Peru that date to several thousand years ago.
Paleontologists spent decades prospecting in Turkey for remains of Homo erectus, widely believed to be the first human species to migrate out of Africa. After moving north, the species had to adapt to increasingly seasonal climates.
The researchers identified this specimen of Homo erectus as a young male based on aspects of the cranial suture closure, sinus formation and the size of the ridges of the brow. They also found a series of small lesions etched into the bone of the cranium whose shape and location are characteristic of the Leptomeningitis tuberculosa, a form of tuberculosis that attacks the meninges of the brain.
After reviewing the medical literature on the disease that has reemerged as a global killer, the researchers found that some groups of people demonstrate a higher than average rate of infection, including Gujarati Indians who live in London, and Senegalese conscripts who served with the French army during World War I.
The research team identified two shared characteristics in the communities: a path of migration from low, tropical latitudes to northern temperate regions and darker skin color.
People with dark skin produce less vitamin D because the skin pigment melanin blocks ultraviolet light. And, when they live in areas with lower ultraviolet radiation such as Europe, their immune systems can be compromised.
John Kappelman, professor of anthropology at The University of Texas at Austin, is part of an international team of researchers from the United States, Turkey and Germany who have published their findings in the Dec. 7 issue of the American Journal of Physical Anthropology.
It is likely that Homo erectus had dark skin because it evolved in the tropics, Kappelman explained. After the species moved north, it had to adapt to more seasonal climates. The researchers hypothesize the young male’s body produced less vitamin D and this deficiency weakened his immune system, opening the door to tuberculosis.
“Skin color represents one of biology’s most elegant adaptations,” Kappelman said. “The production of vitamin D in the skin serves as one of the body’s first lines of defenses against a whole host of infections and diseases. Vitamin D deficiencies are implicated in hypertension, multiple sclerosis, cardiovascular disease and cancer.”
Before antibiotics were invented, doctors typically treated tuberculosis by sending patients to sanatoria where they were prescribed plenty of sunshine and fresh air.
“No one knew why sunshine was integral to the treatment, but it worked,” Kappelman said. “Recent research suggests the flush of ultraviolet radiation jump-started the patients’ immune systems by increasing the production of vitamin D, which helped to cure the disease.”
View of the inside of a plaster cast of the skull of the newly discovered young male Homo erectus from western Turkey. The stylus points to tiny lesions 1-2 mm in size found along the rim of bone just behind the right eye orbit. The lesions were formed by a type of tuberculosis that infects the brain and, at 500,000 years in age, represents the most ancient case
American Journal of Physical Anthropology 7 Dec 2007 Early View DOI 10.1002/ajpa.20739
First Homo erectus from Turkey and implications for migrations into temperate Eurasia
John Kappelman 1 *, Mehmet Cihat Alçiçek 2, Nizamettin Kazanc 3 4, Michael Schultz 5, Mehmet Özkul 2 4, evket en 6
1Department of Anthropology, The University of Texas, Austin, TX
2Department of Geological Engineering, Engineering Faculty, Pamukkale University, Denizli, Turkey
3Department of Geological Engineering, Engineering Faculty, Ankara University, Ankara, Turkey
4JEMIRKO, Turkish Association for Protection of Geological Heritage, Ankara, Turkey
5Zentrum Anatomie der Georg-August-Universität, Göttingen, Germany D-37075
6Laboratoire de Paléontologie du Muséum National d’Histoire Naturelle, Paris, France
email: John Kappelman (email@example.com)
*Correspondence to John Kappelman, The University of Texas at Austin, Anthrop and Archeol, 1 University Station C3200, Austin, TX 78712-0303, USA
Remains of fossil hominins from temperate regions of the Old World are rare across both time and space, but such specimens are necessary for understanding basic issues in human evolution including linkages between their adaptations and early migration patterns. We report here the remarkable circumstances surrounding the discovery of the first fossil hominin calvaria from Turkey. The specimen was found in the Denizli province of western Turkey and recovered from within a solid block of travertine stone as it was being sawed into tile-sized slabs for the commercial natural stone building market. The new specimen fills an important geographical and temporal gap and displays several anatomical features that are shared with other Middle Pleistocene hominins from both Africa and Asia attributed to Homo erectus. It also preserves an unusual pathology on the endocranial surface of the frontal bone that is consistent with a diagnosis of Leptomeningitis tuberculosa (TB), and this evidence represents the most ancient example of this disease known for a fossil human. TB is exacerbated in dark-skinned peoples living in northern latitudes by a vitamin D deficiency because of reduced levels of ultraviolet radiation (UVR). Evidence for TB in the new specimen supports the thesis that reduced UVR was one of the many climatic variables presenting an adaptive challenge to ancient hominins during their migration into the temperate regions of Europe and Asia. Am J Phys Anthropol, 2007. © 2007 Wiley-Liss, Inc.
Human pigmentation variation: Evolution, genetic basis, and implications for public health
Esteban J. Parra
Department of Anthropology, University of Toronto at Mississauga, Mississauga, ON, Canada L5L 1C6
email: Esteban J. Parra (firstname.lastname@example.org) Correspondence to Esteban J. Parra, Department of Anthropology, University of Toronto at Mississauga, 3559 Mississauga Road North, Room 212 North Building, Mississauga, ON, Canada L5L 1C6
Pigmentation, which is primarily determined by the amount, the type, and the distribution of melanin, shows a remarkable diversity in human populations, and in this sense, it is an atypical trait. Numerous genetic studies have indicated that the average proportion of genetic variation due to differences among major continental groups is just 10-15% of the total genetic variation. In contrast, skin pigmentation shows large differences among continental populations. The reasons for this discrepancy can be traced back primarily to the strong influence of natural selection, which has shaped the distribution of pigmentation according to a latitudinal gradient. Research during the last 5 years has substantially increased our understanding of the genes involved in normal pigmentation variation in human populations. At least six genes have been identified using genotype/phenotype association studies and/or direct functional assays, and there is evidence indicating that several additional genes may be playing a role in skin, hair, and iris pigmentation. The information that is emerging from recent studies points to a complex picture where positive selection has been acting at different genomic locations, and for some genes only in certain population groups. There are several reasons why elucidating the genetics and evolutionary history of pigmentation is important. 1) Pigmentation is a trait that should be used as an example of how misleading simplistic interpretations of human variation can be. It is erroneous to extrapolate the patterns of variation observed in superficial traits such as pigmentation to the rest of the genome. It is similarly misleading to suggest, based on the average genomic picture, that variation among human populations is irrelevant. The study of the genes underlying human pigmentation diversity brings to the forefront the mosaic nature of human genetic variation: our genome is composed of a myriad of segments with different patterns of variation and evolutionary histories. 2) Pigmentation can be very useful to understand the genetic architecture of complex traits. The pigmentation of unexposed areas of the skin (constitutive pigmentation) is relatively unaffected by environmental influences during an individual’s lifetime when compared with other complex traits such as diabetes or blood pressure, and this provides a unique opportunity to study gene-gene interactions without the effect of environmental confounders. 3) Pigmentation is of relevance from a public health perspective, because of its critical role in photoprotection and vitamin D synthesis. Fair-skinned individuals are at higher risk of several types of skin cancer, particularly in regions with high UVR incidence, and dark-skinned individuals living in high latitude regions are at higher risk for diseases caused by deficient or insufficient vitamin D levels. Yrbk Phys Anthropol 50:85-105, 2007. © 2007 Wiley-Liss, Inc.