How the Penguins Beat the Heat and Go South
Few animals have evolved to survive in the unforgiving Antarctica like penguins. Species such as the emperor penguin have overlapping layers of insulating feathers, tight blood vessels to recycle body heat, and a stomach sufficient to withstand wind chills approaching minus 80 degrees Fahrenheit. With all these cold weather adaptations, it’s hard to imagine penguins living anywhere else. But ancient penguin fossils have emerged along the Equator, and many of these prehistoric seabirds predate the formation of the Antarctic ice sheet. “They lived through some of the hottest times in Earth’s history, when it was five degrees warmer at the Equator,” said Daniel Ksepka, a paleontologist at the Bruce Museum in Greenwich, Conn. “They basically evolved in an ice-free context. ” To determine how penguins transition from comfortable tropical waters to the polar seas, Dr. Ksepka and his colleagues recently analyzed the genomes of all living penguins, including pipsqueaks such as the foot-h
