Washington, Dec 9 (UNI) Although most scientists believe tuberculosis emerged only several thousand years ago, a new research reveals the most ancient evidence of the disease has been found in a 500,000-year-old human fossil from Turkey.
According to the international team of reserchers, 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, opening door to tuberculosis, the Science Daily reported.
''Skin color represents one of biology's most elegant adaptations, 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,'' John Kappelman, professor of anthropology at The University of Texas said.
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 hypothesise the young male's body produced less vitamin D and this deficiency weakened his immune system, opening the door to tuberculosis.
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 injuries etched into the bone of the braincase 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.