Academic journal article The Science Teacher

City Living

Academic journal article The Science Teacher

City Living

Article excerpt

New research has found that a genetic variant that reduces the chance of contracting diseases, such as tuberculosis and leprosy, is more prevalent in populations with long histories of urban living. The research, published in the journal Evolution, shows that in areas with a long history of urban settlements, today's inhabitants are more likely to possess the genetic variant that provides resistance to infection.

In ancient cities, poor sanitation and high population densities would have provided an ideal breeding ground for the spread of disease. Natural selection should mean that humans would have developed resistance to disease in longstanding urbanized populations over time. However, this association has been difficult to assess--especially in prehistory.

Now, scientists from University College London (UCL) and Royal Holloway have tested the theory by analyzing DNA samples from 17 different human populations living across Europe, Asia, and Africa. In addition, they searched archaeological and historical literature to find the oldest records of the first city or urban settlement in these regions.

By comparing rates of genetic disease resistance with urban history, they showed that past exposure to pathogens led to disease resistance spreading through populations, with our ancestors passing their resistance to their descendents.

"The results show that the protective variant is found in nearly everyone from the Middle East to India and in parts of Europe, where cities have been around for thousands of years," says Professor Mark Thomas from the Department of Genetics, Evolution, and Environment at UCL. …

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