Older origins of measles virus Animal domestication by humans is thought to have given many pathogens an opportunity to invade a new host, and measles is one example of this. However, there is controversy about when measles emerged in humans, because the historical descriptions of measles are relatively recent (late ninth century CE). The controversy has persisted in part because ancient RNA is thought to be a poor target for molecular clock techniques. Düx et al. have overcome the ancient RNA challenge by sequencing a measles virus genome obtained from a museum specimen of the lungs of child who died in 1912 (see the Perspective by Ho and Duchêne). The authors used these and other more recent sequencing data in a Bayesian molecular clock–modeling technique, which showed that measles virus diverged from rinderpest virus in the sixth century BCE, indicating an early origin for measles possibly associated with the beginnings of urbanization. Science , this issue p. 1367 ; see also p. 1310