Bears are among the most massive and powerful animals on earth. They are also very intelligent. They can use tools, they have a remarkably acute sense of smell, good eyesight and hearing, and they hibernate during inhospitable winters when the pickings are slim for food.
Hibernating brown bears will stay in their dens for up to seven months without eating or drinking. Somehow their bodies recycle waste without having to urinate or defecate. Their metabolism and heartbeat slow down considerably as they enter a not-quite-deep-sleep state known as “torpor” that enables a bear to sense environmental stimuli without becoming aroused. How is this possible?