Interview with Ross MacPhee What killed the mammoths and other behemoths that once roamed the Americas? This mammalogist thinks it may have been hyperlethal disease Image: Clare Flemming Around 11,000 years ago, at the end of the Pleistocene epoch, North America witnessed an extinction that claimed its mammoths, giant ground sloths, camels and numerous other large-bodied animals. Exactly what happened to these megafauna is unknown. Indeed, researchers have puzzled over their disappearance for decades. Traditional explanations hold that either dramatic climate shifts, or human hunting (overkill) extinguished these species. But in recent years a new hypothesis has emerged. According...