We have the dubious privilege of observing a new disease in the midst of being born. The disease could go on to spread around the world, stall out as a minor, local blight, or disappear altogether. Scientists have been observing its emergence for a year now, and while they know more than they did in 2012, they still can’t predict quite what will happen. Part of their uncertainty stems from the fact that they still don’t know much about its past.

The disease I speak of is Middle Eastern Respiratory Syndrome–MERS for short. Last fall, doctors began recognizing this pneumonia-like disease in people who either lived in or passed through Saudi Arabia. Virologists soon isolated a virus common to them all,