The lungs of a two-year-old girl preserved in formalin (formaldehyde) for a century have made it possible to reconstruct the history of measles. The disease has been affecting children for at least 2,500 years. It was then that, according to the study of the pathogen lodged in the little girl, the virus jumped from cows to humans. The divergence coincided with the emergence of the first large human cities that facilitated the spread and survival of the disease.
