I recently read about a family that had been living in a remote area of Russia for 40 years! Their youngest children had not seen another human outside of their family for decades. No electricity and very little food to eat. A team of geologists found them by chance one day living on the side of a mountain. The youngest son was able to hunt out in the cold with his bare feet and stay out for a few days. It's amazing how the human body can adapt to the environment.
Here is the article if you want to read about this family: