Wikipedia:Today's featured article/August 18, 2013

The social history of viruses describes the influence of viruses and viral infections on human history. Epidemics caused by viruses began during the Neolithic period. Having been hunter-gatherers, humans developed more densely populated agricultural communities, which allowed viruses to spread rapidly and subsequently to become endemic. Smallpox and measles viruses are among the oldest that infect humans. Having evolved from viruses that infected animals, they first appeared in humans in Europe and North Africa thousands of years ago. Louis Pasteur and Edward Jenner were the first to develop vaccines to protect against viral infections. The nature of viruses remained unknown until the invention of the electron microscope in the 1930s, when the science of virology gained momentum. In the 20th century many diseases both old and new were found to be caused by viruses. HIV is the most pathogenic new virus to have emerged in centuries. Although scientific interest in viruses arose because of the diseases they cause, most viruses are beneficial. They drive evolution by transferring genes across species, play important roles in ecosystems and are essential to life.

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