THEY COST AN ARM AND A LEG

Prosthetic limbs. When an arm or leg is lost—either by amputation or injury—it cannot be regenerated as some salamanders are able to do. Our ability to regrow body parts is limited to our fingertips. The only option for an amputee is to get an artificial appendage, made of plastic and metal rather than flesh and bone.

Prosthetics is an ever-advancing field of technology. Last century, hands were replaced by mechanical hooks, but nowadays you can get a sophisticated robotic hand, including an opposable thumb. Mechanisms of the past relied on physical movements of the shoulder and arm to operate, but the newest prostheses sense electrical signals generated when users simply think of using their hands.

Prostheses are no longer limited to amputees, though. People with paralysis are getting involved. Multiple patients in Austria have chosen to have their hands amputated and replaced with prosthetic ones. They had nerve damage in their arms, rendering their hands paralyzed and useless. They could have endured years of surgery and rehabilitation with little chance of success. But circuits and software are more easily and reliably manipulated than nerves and sinew. So those patients chose the option with a greater chance of success and shorter recovery time.

Artificial body parts are helping many people. A tiny camera can be placed inside or near the eye and connected to brain, some day giving sight to the blind. Carbon-fiber “feet” can enable an amputee to race with Olympic sprinters. Faulty hearts have been replaced with inorganic ones. Soon artificial kidneys might become available. But what if prostheses become better than natural parts?

In the future, prosthetic technology will continue to improve and be more widely used. Given the progress that has already been made, it is not unreasonable to speculate that someday a bionic hand will be superior to a fully functional, natural hand. Those patients in Austria made a logical choice: they exchanged useless hands for functional ones. If, some day, you are better off exchanging your properly working hand for a much more capable and versatile—albeit artificial—hand, would you? Natural appendages degrade with age, but inorganic parts can be updated and replaced with relative ease. Customization could be easy, too. Instead of a hand, you could have a tentacle, claw, multi-tool, or even scissors. How about eyes? Would you trade one or your eyes for a cybernetic one that could see infrared and ultraviolet light? Would you give an eye for an eye that could see in the dark and through walls? Maybe far in the future we will have whole prosthetic bodies available.