ArmFull

My late father once wrote a short-story in which the protagonist wore a hearing aid.  The protagonist's hearing was fine, but he thought that the aid might make it even more sensitive than that of his unenhanced ears.  In the story the idea didn't work very well, and I suspect that that would also be true in real life - it would certainly be a simple enough experiment to try.

About six years ago there was a minor (which is to say widely e-mailed then forgotten) fuss about Jie-jie shown above, who was born with three arms.  Neither of his left arms was fully functional, but they had such similar - if partial - abilities that there was a long debate about which to amputate.  At the time it seemed to me rather sinister (there's a joke for the Latin-literate in there somewhere) that no one involved was strongly advocating leaving both of them alone on the basis that one good arm plus two partially-functioning ones might be a lot more useful than one-and-a-half in total.

I was reminded of this when I dug my father's story out.  There is a lot of work being done on artificial arms for amputees.   These arms are powered and active, being controlled by nerve impulses that would be sent to the real arm if it existed.  And they can be given abilities that no real arm has, such as continuous rotation at the wrist, or a multimeter wired into the finger and thumb, so the owner can analyse working electronic circuits.

Why not develop these for the able-bodied too?  They have fully-functioning nerve signals that can be tapped for control, and it should be reasonably straightforward to separate the signals for the real arm from those for the fake: all that's needed is the equivalent of a shift key - something like curling up one's little finger would do.

We would all be more dexterous with an optional extra arm strapped to our shoulders...