ali: nilesh christopher, thank you so much for joining us. thanks, ali. ♪ john: bears aren't the only animals settling in for their winter hibernation right now. arctic ground squirrels can lower their body temperatures to freezing levels and stay dormant for up to eight months. researchers at the university of alaska in fairbanks are studying how these squirrels can survive on the edge of life. and as alaska public media's kavitha george reports, they may hold clues to treating injuries and disease in humans. this story was produced in collaboration with nova with major support from the corporation for public broadcasting. kavitha: this little squirrel just came out of the a lab freezer. but it's not dead. and scientists like sarah rice want to know why. sarah: there's no cardiac arrest, there's no stroke, they're obese, but there's no ill effects, there's no bone loss. kavitha: this is an arctic ground squirrel, and during hibernation, it can chill its body down to the freezing point -- 32 degrees fahrenheit. it's the only mammal that we kn