This afternoon, Terry Gross had an interesting interview with Hugh Herr, who runs a lab at MIT that designs artificial limbs. Herr is also a user of his designs; both his lower legs were amputated due to frostbite from a mountain climbing incident when he was a teenager. Herr argues that his artificial legs are superior to natural legs in many ways, particularly since he has multiple pairs tailored to different uses. But here's what's really provocative:
"My biological body will degrade in time due to normal, age-related degeneration. But the artificial part of my body improves in time because I can upgrade. ... So I predict that when I'm 80 years old, I'll be able to walk with less energy than is required of a person who has biological legs, I'll be more stable, and I'll probably be able to run faster. ... The artificial part of my body is, in some sense, immortal."
It's undoubtedly true that the technology will get better and better. And we can presume that the cost for sophisticated prosthetics will decline over time. So here's my question: when do people start getting prostheses not because their legs have been lost due to an accident, but just because they're worn out due to age? As they grow more sophisticated, the prostheses will eventually be controlled by the wearer's own nervous system, and will integrate enough sensors that they will simulate (or duplicate, depending on how you think of it) touch sensations as well. So if you were an 80-year-old with creaky knees, and you could lop off your old legs and attach a pair of artificial legs that were stronger, less pain-ridden, and allowed you to dance and run and do all the things you haven't been able to do for twenty years, would you take it?
Many people might say no right now, but I'd wager that in a few decades, this will become common, and we will consider it no more radical an attack on what it means to be human than hearing aids or contact lenses.