Monarch memory

Monarch butterflies migrate from southern Canada to central Mexico in relay style, laying eggs along the way, because the arduous journey takes longer than their lifespan. The eggs become caterpillars and the caterpillars form chrysalises (VIDEO HERE) and from the chrysalises emerge butterflies that continue the migration. But instead of flying in a straight shot over Lake Superior, they fly south, then turn east for a while, then turn south again. Contributing editor at io9 Esther Inglis-Arkell explains: "Biologists, and certain geologists, believe that something was blocking the monarchs' path. They believe that that part of Lake Superior might have once been one of the highest mountains ever to loom over North America. It would have been useless for the monarchs to try to scale it, and wasteful to start climbing it, so all successfully migrating monarchs veered east around it and then headed southward again. They've kept doing that, some say, even after the mountain is long gone." While the ephemeral lives of Monarch butterflies are measured in weeks, their collective memory is measured in geologic time...

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