The thought of humans having wings, tentacles or an extra arm may all seem rather unlikely.
But these scenarios could actually become reality in the next few decades, thanks to leaps in human augmentation.
Researchers have already designed a ‘Third Thumb’ controlled by foot movements, which allows the wearer to unscrew a bottle, peel a banana or thread a needle using just one hand.
Now, experts believe the thumb is just a first step towards larger, more dramatic additions to the human body.
Tamar Makin, a professor of cognitive neuroscience at Cambridge University, said the brain’s ability to adapt to an extra limb was ‘extraordinary’.
The thought of humans having wings (artist’s impression), tentacles or an extra arm may all seem rather unlikely. But these scenarios could actually become reality in the next few decades, thanks to leaps in human augmentation
But scaling the design up to larger augmentation devices comes with its own hurdles.
‘The big question is how do you control a body part that you’ve never had before?’ she said.
‘When we work with technology for substitution, like prosthetic limbs, the aim is pretty straightforward.
‘But, in augmentation, I want you to continue to use your body to its fullest capacity and on top of that, give you an extra body part.
‘We are also worried about what we call the resource reallocation problem – what if I’m stealing resources from the feet in order to give one to the hands?’
When asked whether it would be possible to design wings or even tentacles for human use, Professor Makin said: ‘Yes, from a technical perspective. The technologies are out there, we just need to scale them.
‘There are technological issues to deal with, for example you want it to be wearable, comfortable, it can’t be heavy and it can’t be plugged into an electric socket.
‘Control is the real issue. So wings are actually really simple because it’s just one degree of freedom – up and down.
‘But when you’re doing something more complicated, like a tentacle, we need a lot of control.
‘For example, if you want to reach your cup of coffee because it is far away, you want to use your tentacle.
‘But if you really need to focus because it’s a really complicated task, then just standing up would be less disruptive.’
When asked whether it would be possible to design wings or even tentacles for human use, Professor Makin said: ‘Yes, from a technical perspective. The technologies are out there, we just need to scale them’
Researchers have already designed a ‘Third Thumb’ controlled by foot movements, which allows the wearer to unscrew a bottle, peel a banana or thread a needle using just one hand
Her colleague Dani Clode was the brains behind the Third Thumb, which was first unveiled in 2017.
The robotic 3D printed digit is worn on the side of the hand opposite the user’s actual thumb.
The wearer controls it with pressure sensors attached to their feet, on the underside of the big toes, with a wireless connection linking the two.
For their study, 20 participants were trained to use the thumb over five days – for example using it to pick up multiple balls or wine glasses with one hand.
They learned the basics of the thumb very quickly and were even able to use it while distracted or blindfolded.
Writing in the journal Science Robotics, the team said participants also increasingly felt like the thumb was a part of their own body.
The robotic 3D printed digit is worn on the side of the hand opposite the user’s actual thumb
Before and after training, the researchers scanned participants’ brains. They discovered subtle but significant changes to the organisation of neural circuits that light up when we use our hands.
Professor Makin said: ‘Evolution hasn’t prepared us to use an extra body part, and we have found that to extend our abilities in new and unexpected ways, the brain will need to adapt the representation of the biological body.’
Ms Clode has also designed a robotic, coiling tentacle that acts as a prosthetic arm.
Named ‘Vine 2.0’, it has 26 individual vertebrae that are controlled by the wearer with pressure sensors and electronics in shoes.
Silvestro Micera, from the Sant’Anna School of Advanced studies in Pisa, is also working on a third arm that is attached to the body around the waist and controlled by breathing.
The researchers will discuss their advances in augmentation at the annual conference of the American Association for the Advancement of Science in Washington.