John Hoffecker has written a compelling account of how humans, who evolved in the tropics, came to inhabit some of the coldest places on earth over the span of nearly two million years. Far from diffusing gradually northward from their African origins, people settled Europe and northern Asia, the Arctic, and the Americas in relatively rapid bursts. This book traces the complex history of anatomical adaptations, diet modifications, and technological innovations that allowed humans the continued ability to push the boundaries of their frontier. It concludes by showing how in the last few thousand years, peoples living in the circumpolar zone--with the exception of western and central Siberia--developed a thriving maritime economy. Drawing on a number of diverse disciplines, Hoffecker's is the first book to explore human adaptation to cold environments at such an extensive scale.