You Can Go Home Again

Shifts in ocean currents and the development of Antarctic bottom waters drop ocean temperatures by as much as five degrees centigrade. Life thrives and expands in these nippy, nutrient-rich ocean waters.

Perhaps some combination of increased ocean productivity, shifting sea margins, the complexities of megafaunal movement on land, and a nostalgia and logic we've yet to understand — inspires a change. The whales' land-roving mammalian ancestors, after thoughtful ambling on the edge, return to the sea. They do go home again.