Modern prosthetics go beyond artificial limbs—and into the human brain

The future is here.
The future is here.
Image: Reuters/Rick Wilking
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When most people think of prosthetics, they think about artificial arms or feet, or maybe the carbon fiber legs used by Olympic runner Oscar Pistorius. But if we factor in any mechanical enhancement of human ability, prosthetics actually have a much richer history, and a much broader future.

Already, there are hints of a future in which prosthetics enhance human abilities, rather than struggling to match them. But that future also invites a lot of questions, like: What does it mean to be a “natural” human? And when no one is one anymore, who gets left behind?

Executive editor and Quartz Obsession podcast host Kira Bindrim spoke to senior reporter Samanth Subramanian about the future of human augmentation. Read the full transcript of the episode.

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What is the story of the first prosthetic?

Samanth Subramanian: Well, I mean, one of the earliest things that have been described as a prosthetic was actually a fake eye. It was made of bitumen paste, so it’s kind of like tar, and covered in gold. And it was found in a tomb in ancient Iran, from around 3000 BC. But that isn’t really a prosthetic, I’d argue, because there’s no functionality to it, you can’t really see out of it. So the earliest true prosthetic we know was this wooden big toe that you spoke about. It dates to around 1000 BC, it was found attached to the right foot of a mummified Egyptian woman who’d lost that big toe. And we don’t know why she had it. One theory is that she had gangrene and it had to be amputated. But the big toe is so crucial to how we walk and maintain balance, that there was a need for a prosthetic and this must have been remarkably effective. So was essentially just tied on to the remainder of the foot. And she would have sort of walked on that until the day she died.

It’s interesting to think about this continuity of human need, that our bodies are essentially frail, liable to break down, and that physical malfunctions happen and they’ve been with us forever. But around the time of this big toe, around 1000 BC, we see the start, the rudiments of the human effort to overcome these malfunctions with things we can make—with prosthetics.

What started the next era of prosthetics?

Samanth Subramanian: Well, with the caveat that maybe any so-called ‘start’ to an era is probably going to be entirely arbitrary, I’m going to be bold and I’m going to say that the age of prosthetic enhancement started on a lake in Arizona in the summer of 1976. And so that day, there was a guy named Van Phillips, he was a 21-year-old student at the University of Arizona at the time. And he was waterskiing when a really terrible accident happened: A passing motorboat cut off his left leg six inches below the knee. And he had to wear a clumsy prosthetic, which he described as a pink foot attached to an aluminum tube. But Phillips was so sort of discontent and dissatisfied with this, that he became a biomechanical engineer himself, and he started trying to design a better leg. And that was really the pivot, or the start of a new era. A couple of things happen in the 1980s, when Van Phillips and a few others are working in this field. So one is that materials start to get a lot more sophisticated. You know, the aerospace industry in particular had these refined carbon fiber composites. And they were making lighter and stronger materials out of carbon fiber. And Van Phillips came up with this idea that a prosthetic foot didn’t have to look like a human foot. So instead, he looked to the shape of a cheetah’s hind leg, to that curved sort of L-shape that you can see on the back of a cheetah. And so when the animal lands on the ground at 50 miles an hour, Phillips in one interview, that long tendon is being stretched like a catapult. It’s the long tendinous fibers that propelled the animal forward. So this was really his big insight. The foot he designed, which he called the Flex-Foot, that was really the precursor to the kinds of prosthetics we see now, for example, in the Paralympics. It’s the kind that Oscar Pistorius, the Blade Runner, wore. And the reason we can start to talk about it as enhancement rather than just replacement is because of how advanced these prosthetics have become. So there’s a company called Össur in Iceland, which is also incidentally founded by a guy who lost part of his leg when he was young, they’ve been around for 50 years now, they make so many of these prosthetics that you see at the Paralympics—these running blades that are made out of really thin layers of carbon all sandwiched and compressed together. And they test it so thoroughly. I mean, the one statistic that I have for this podcast is that every running blade goes through 2 million cycles of tests, and each test is with a 300 kilogram weight on top of the blade. So it’s the equivalent of running a marathon a week for a year. That’s the kind of stringency and testing that you see now in the prosthetic field.

What are the different types of prosthetics?

I mean, you know, the notion of the prosthetic is that it’s with you all the time. And it’s enhancing your abilities, which is why actually, I would argue that our smartphones are prosthetics as well, in a way: They’re with us every waking second, they’re basically extensions of our hands that are augmenting our mental capacities. There was a point back in 1998, when a couple of philosophers argue just this, the technologies that extend our minds become a part of us, in no different way than the old Egyptian wooden toe.

We’re sort of downloading our brains into the computer, so to speak, right? I mean, we don’t remember phone numbers anymore, or birthdays. And these are things that people used to remember back in the day. And so whether you want to think of the mind as the storage drive of a computer, and you want to think about the mind freeing up space to do other things, that’s really a kind of enhancement and augmentation as well. Now, scientists of the mind will tell you that the mind doesn’t really work that way. You don’t really free up space, you just kind of have different parts of the brain allocated for different things. But it’s definitely sort of a relief sometimes to not have to remember some of these other trivial details. The other kind of obvious related enhancement that we sort of flirted with as a species for a while was Google Glass, which is really the phone, but sort of up close and personal in your spectacles for people who don’t need spectacles. And the idea was, again, a sort of visual and mental augmentation enhancement. It was a way to bring this kind of computerized enhancement to the everyday experience of seeing, but also to the everyday experience of recalling and remembering. And while in its time Google Glass was sort of derided, it really seems to be the obvious transition point for a computer to then sort of get even closer to us than it already is.

What is the future of the prosthetic?

Samanth Subramanian: Well, the future of the prosthetic is really neural, I think. It’s a way in which we can hook up our brains and nerves with our prosthetics to be able to control them with our thoughts, with our minds, the way we control our own limbs. And, of course, the most outlandish example of this right now that’s imaginable, which is a computer inside the brain, is also the kind that Elon Musk is pursuing. Naturally, I mean, that’s just what he does. So he set up a company called Neuralink, and he put $100 million into it. And just a few days ago, Kira, before you and I are speaking, he said that the Neuralink implant technology is very close to human trials. And obviously, scientists are really worried about this, about what it means for health and privacy, about what it means for this sort of technology becoming yet another consumer product. But there also seems to be a consensus right now from scientists that a full-fledged computer sitting in your brain, putting the equivalent of the internet at your mental command, at your mental fingertips, is a long way away.

How would Elon Musk’s Neuralink work?

Samanth Subramanian: Well, what good Elon Musk wants to do in general is open to, you know, fair question and argument. But with this one, I imagine he is so wedded to the culture of the computer. And he thinks that the internet and the computer and digital enhancements in general are so much of a good thing that it seems to him to be an automatic step to try to integrate that with the human brain itself. I think he sees the human brain as fallible, I think he sees it as frail, and I think he sees it at the same time as infinitely more creative if only it could process more, or if only it could have more information at its disposal. And so I would imagine the good that he wants to do is he wants to unlock some of this capacity that he sees in the human brain, and he wants to do it with the computer sitting in the brain. Whether that is actually feasible or realistic is another question altogether. And I think a lot of scientists have very severe doubts about this.

What will prosthetic enhancements look like in the future?

Samanth Subramanian: Well, I mean, the Neuralink, as I said, is sort of fantasy at the moment. I think much closer are the kinds of enhancements that we call exoskeletons right now. These are sort of prosthetic frames that fit onto our limbs or our bodies that we can control with neural commands, possibly, and that gives us enhanced physical abilities. The two immediate uses that people are talking about for war and consumerism, which says a lot about our society, I guess. So soldiers are supposed to be able to use exoskeletons to become super soldiers and warehouse workers might end up using exoskeletons to lift heavier pallets and shipments. Then there’s things like artificial organs, which we might be able to swap into our bodies when it feels like our kidneys or heart are failing, or even if they aren’t failing. I mean, these would be prosthetic enhancements as well. You know, so outside of the Neuralink sphere, there’s a number of dominant players in this right. I mean, there’s a company called Ekso Bionics, which is based in California, which does exoskeletons, and that’s listed on NASDAQ. There’s a big company like Lockheed that is also experimenting with exoskeletons. There are small companies, startups like Jarvik Heart and Bivacor that talk about building artificial hearts. And surely, I mean, there’s stuff going on in the Department of Defense that we don’t know about. There’s a couple of companies in China, there’s a couple of companies in Japan. It’s worth saying at the moment that a lot of these companies, Musk aside, are still talking about using prosthetics to help the differently-abled or the infirm or the elderly. But there is a parallel future that’s easy to envision here in the adoption of prosthetics by the able-bodied human.

How will prosthetics be used for human enhancement?

Samanth Subramanian: Yeah, I mean, I think the problem is exemplified by Neuralink. I think one of the problems that people are talking about with this is they worry that the kind of funding and research attention that a Neuralink gets is actually distracting from a lot of other things that our differently-abled need. And some of that stuff can be really basic—it can be city infrastructure for people who find it difficult to get around the city. But it can also be finding ways to just get basic prosthetics or even advanced prosthetics to people who need them. When I was talking to somebody at Össur, they made this point that was extremely insightful, which is that what they really want is to be able to give regular people who are differently abled a way to have an everyday leg and then a way to also have a sprinting or a running leg, the kind that athletes use. And they can’t do that right now because insurance companies will not cover, you know, an athletic prosthetic, so to speak. But it’s important, it’s important for people to be able to want to run and to be able to exercise and, you know, these are the kinds of problems that are there in the here and now. And the drive to create prosthetic enhancements for able-bodied humans, I’d argue, is actually sort of distracting from some of these other present problems that people already have.

What are the implications of introducing human enhancement?

Samanth Subramanian: Well, I think, you know, as is always the case with human society, I think we will wish that we had thought a little bit more about regulation and ethics, I’m guessing. I mean, it’s the same with genetic engineering, in a way. These scientific changes may overtake us before we are ready for them from a systemic point of view. And at that point, we’ll be forced to play catch up and to frame rules and codes for them, and we’ll be presented with the prospect that the wealthy, who are already advantaged, will augment their privilege by buying these enhancements. And whether it’s some Neuralink or genetic improvement, you can imagine what that does to the inequities in society that already exist.

I think the question of accesses is incredibly useful. I think, you know, what we’ve established here in this sort of long 3,000-year narrative of prosthetics is that it’s already gone, or is in the process of going from being something that helps people who are missing a human ability, to helping people who have all their faculties with them, but want to perform at some kind of super level, whether it’s for a competitive sport, or whether it’s for, you know, labor and society, or whether it’s for war. And I think the the danger here is that this will become yet another kind of consumer technology that you can just sort of buy off the shelf. And the minute that happens, there’s all sorts of problems that creep in in terms of who’s going to be designing prosthetics for the people who genuinely need them.