Monarch Origin Shocks Scientists

Monarch butterflies are famous for migrating from the US and Canada to Mexico for the winter. Now a surprising study in Nature suggests the species itself also started out in North America some 2 million years ago. A researcher from the University of Chicago says monarchs were widely thought to have evolved in South or Central America instead. But DNA from 80 monarchs sampled from the Americas and as far away as Europe and Australia points to a North American origin, maybe in the southern US or northern Mexico.

The researcher adds scientists had thought the monarch arose from a non-migrating ancestor. But the new study concludes the ancestor did migrate. Meanwhile, experts in Mexico this week announced a tentative sign of hope for the mass migration of monarch butterflies, whose numbers dropped to their lowest level ever last year. (More butterflies stories.)