Mankind’s greatest advantage over the rest of the animal kingdom isn’t just its larger brain. It’s another, smaller evolution, shared with but a few primates, that has allowed humans to master tools that evolved from sharpened sticks to multitouch iPhones: the opposable thumb.
So we have a question for you: Would you like another?
Because Royal College of Art graduate Dani Clode has developed an intriguing prosthesis called the Third Thumb. Featured on Dezeen, it’s not a replacement thumb for amputees, but an additional thumb for anyone who might find the possibility empowering. “I came across the origin of the word prosthesis and found that it meant ‘in addition to,'” says Clode. “This inspired me to reframe prosthetics as extensions, rather than anything that ‘fixes’ or ‘replaces.'”
In other words, she imagined the prosthetic as a small superpower that anyone might opt into as easily, and as commonly, as they might put on a pair of glasses or earrings. It’s actually a popular concept at the moment. Scientists from the Inami Hiyama Laboratory recently debuted a prosthetic third arm, called the MetaLimb, and even Facebook has teased wearables that would read your mind and let you feel messages on your skin.
As for the Third Thumb, it slips onto your hand much like a glove. The appendage itself is driven by two small motors, and you activate these motors by pushing on pressure sensors with your toes. As strange as this control scheme may sound, it’s common in prostheses–the MetaLimb, and even Dean Kamen’s robot arm, have used similar foot controls.
These controls take all of a minute to learn but a bit longer to master, as figuring out just the right amount of toe pressure to apply for various tasks takes some learning. But there’s a payoff. In the above video, Clode shows herself practicing all sorts of feats with the thumb, from holding four wine glasses at a time, to closing a pair of sunglasses with one hand.
“I no longer think about pressing my toe down to move it—I think about bending the thumb, and my toe automatically presses down. But this is a similar kind of feeling to driving, or a sewing machine,” says Clode, who has worn the prosthetic up to six hours a day. “You don’t think about putting your foot down after a while—you think about moving forward and your foot goes down.”
The thumb’s most successful implementation, she says, was with a musician who was able to use the extra finger to hit difficult chords on the guitar. Because he was already so used to using foot pedals to augment the guitar’s sound, the transition required a minimal mental leap. In the future, she’d like to test the device across demographics, trying it with everyone from toddlers to falconers to see how they might use an extra appendage uniquely.
In the meantime, the prosthetic thumb is serving as an intriguing case study on her own body–one that teases a possible future, in which small, wearable robotics become so inexpensive and mindlessly smart that our own fleshy bodies could learn to rely on them.
“After a while of wearing the thumb, I do feel like something is missing after I take it off,” says Clode, “which is an unusual and an interesting experience.”