In "Ends of the Earth," Neil Shubin travels north and south to explore the frontiers of polar science and history.

The pictures of polar bear moms and cubs emerging from their dens in Svalbard, Norway, shine valuable light on the reproduction process of the threatened species, say scientists. Polar bears ...

Editor's Note: National Geographic went too far in drawing a definitive connection between climate change and a particular starving polar bear ... that our images of this dying bear moved the ...