John F. Hoffecker is a fellow of the Institute of Arctic and Alpine Research at the University of Colorado, Boulder. He received his Ph.D. from the University of Chicago and has conducted field research in Alaska and Russia. He is the author of A Prehistory of the North: Human Settlement of the Higher Latitudes, and in 2005 he received an honorary degree from the Russian Academy of Sciences.Scott A. Elias is professor of quaternary science at the Royal Holloway College, University of London, and adjoint fellow at the Institute of Arctic and Alpine Research. Elias grew up in Colorado and attended the University of Colorado, receiving a B.A. and then a Ph.D. in environmental biology. His research focuses on the reconstruction of Pleistocene terrestrial environments using data from fossil insect studies.