Science New study of a pathogen’s Bronze Age spread challenges longstanding links between disease and early agriculture. A now-obscure cousin of Lyme disease called recurring fever was a scourge of early civilization. Caused by the bacterium Borrelia recurrentis, it results in crippling headaches and repeated bouts of high fever; if left untreated, it damages organs and even leads to death. Like other diseases that tormented the ancient world, including leprosy and the plague, it seized the opportunity to jump from animals to humans when farming and domestication originated about 11,000 years ago—or so researchers thought.
A paper published today in
Science traces the bacterium’s winding evolutionary history to argue that recurring fever began to flourish much later, around the advent of metal tools during the Bronze Age. The evidence, from ancient bacterial genomes, suggests the pathogen switched from being a generalist transmitted among mammals by ticks to a specialist transmitted by human body lice some 5000 years ago, perhaps when people in Europe began to wear wool clothing. “It’s a cool paper, I must say,” says Ben Krause-Kyora, a geneticist at Kiel University who was not part of the new study. “It really goes into depth to show the evolution of the pathogen itself.”