Inventors and researchers have been developing robots for almost 70 years. To date, all the machines they have built—whether for factories or elsewhere—have had one thing in common: They are powered by motors, a technology that is already 200 years old. Even walking robots feature arms and legs that are powered by motors, not by muscles as in humans and animals. This in part suggests why they lack the mobility and adaptability of living creatures.Inventors and researchers have been developing robots for almost 70 years. To date, all the machines they have built—whether for factories or elsewhere—have had one thing in common: They are powered by motors, a technology that is already 200 years old. Even walking robots feature arms and legs that are powered by motors, not by muscles as in humans and animals. This in part suggests why they lack the mobility and adaptability of living creatures.[#item_full_content]