At Smithsonian Magazine: That Mammuthus columbi originated as a new species, born of a hybridization event, “has major implications for our understanding of the population structure of Pleistocene megabeasts,” MacPhee says. The ancestors of the woolly mammoth and the Krestova mammoth had diverged from each other for about a million years before a population produced a hybrid that was different from both, giving rise to Mammuthus columbi.