The ground squirrel and the Syrian hamster, two rodents that hibernate in the winter, do not feel cold in the same way as non-hibernators, such as rats or mice. Yale researchers have discovered that hibernating rodents evolved cold-sensing neurons with diminished ability to detect temperatures below 20 degrees Celsius. This adaptation potentially allows their body temperature to drop for long periods of time without causing them to feel stressed by these conditions, thus triggering their seasonal slumber. The work appears December 19 in the journal Cell Reports.