Over the past 10 days or so, we’ve highlighted multiple advances in medicine and technology that could change medical care as we know it in the not-too-distant future. For our final deep dive on the topic (for now), we’re going to address one of the most difficult questions of all, a difficulty that mankind has been struggling to overcome at least since Qin Shi Huang died from ingesting mercury in a bid to make himself immortal: Human longevity. And while immortality remains firmly outside our grasp, we’re using technology to improve human longevity today, and have been since the adoption of fire and simple machines. Using medical technology, we can attack the problems limiting human lifespan.

What kind of technology has (or could have) direct lifespan extension capabilities?

In this instance, we’re defining direct lifespan extension capabilities as those things that specifically counteract aging or causes of death. Ultimately, there are both internal and external factors that cause cells and organisms to age and die. External things like UV radiation (Baz Luhrmann — wear sunscreen!) cause DNA damage which can trigger a cell’s self-destruct mechanisms. Within and between cells, the molecular flotsam and jetsam of life build up like crumbs in the cupholders of a car, causing a condition called senescence. Senolytics, which are substances that unclog the works by selectively inducing the death of senescent cells, can address that problem. Senolytics have been shown to extend healthy adulthood in mice, but as usual, it’s not clear yet whether that will translate to humans.

Telomerase is another likely player in the fight against aging. Telomeres are regions of disposable DNA that cap off the ends of chromosomes, preventing the sticky ends of DNA from attaching somewhere they shouldn’t. During life, repeated handling can shorten telomeres, and when telomeres get too short, DNA replication gets buggy, which can also lead to cell death. Telomerase is an enzyme that prevents this degradation, sort of like the protective border around a Polaroid. Getting the benefit out of telomerase isn’t as simple as taking telomerase pills to live longer, but we don’t know exactly why yet.

In fact, the whole idea of senolytics is that we can get finer control over the cell cycle, so that we can tell cells when to die and when not to. It’s much less a statement about any single therapy than it is a statement about the relative level of scientific advancement needed to make these biotechnologies work.

Then there are more indirect forms of technological life extension. We’re defining “indirect” life extension as technologies that prevent unnecessary deaths, extend valuable years, or reduce stress that leads to aging and infirmity. Falling into this category are things like smart houses — alert and first aid systems that can prevent deaths and make daily living easier. But there are also inventions like the exoskeletons we’ve covered recently and even materials-science innovations like, say, an implant or indwelling device made from a highly hydro- and oleophobic material that can repel biofilm adhesion.

Personalized health care, in particular BayMax-like personal health care assistants, also represent a coming sea change in how we age. To the extent to which AI is actually better than human doctors, it will take over the practice of medicine, no matter how unflattering it may feel at the time.

“Dietary supplements” and megadosing, though, are going the way of the superfood craze. Like every other dietary fad, nutraceuticals are of limited use outside the narrow set of conditions where they’ve been found to work. If you’ve read about the genuinely dismal state of the dietary supplement industry, you may be familiar with this problem. When Ray Kurzweil spoke at RIT in 2008, he had with him a gallon-size Ziploc that he said held the several cups of pills he claims to take per day. Kurzweil is among others hoping to hedge their bets and extend their lives with liberally applied nutraceutical-grade snake oil, proving that you can be smart, well-intentioned, well-informed, and still just plain wrong. The best argument in favor of nutraceuticals is “Hey, it can’t hurt.” There is no dietary magic bullet for life extension, and if you’re trying the “spray and pray” method like Kurzweil, you’ve already lost.

This brings us to the singularity.

The general idea of a technological singularity is a future where technology has advanced so far that it outstrips the ability of humans to understand it. There are, more or less, two ways the scenario can play out: in favor of humans, or in favor of the AI. Kurzweil and his singularitarians tend to believe that if humans can ride the wave of advancing technology, forming a harmonious relationship with it, we can enhance our own intelligence to the point of transcending our physiological bounds. In certain possible futures, this could mean directly augmenting the body and brain with cybernetics in order to improve or extend function or lifespan.

If — and this is a big if — we had sufficient computing prowess and sufficiently advanced understanding of the crossroads between body and mind, we could even budge up against mind uploading. Setting aside the difficulties of storage media and whether or not the Matrix is a good idea, mind uploading could neatly circumvent mortality by representing your consciousness as a lossless set of nodes and waveforms and their associated Boolean logic, which could be easily transmitted between systems, like a PDF.

Gordon Moore, of Moore’s Law, actually argued against the idea of a technological singularity. He wasn’t convinced that the miniaturization of transistors could make them suited to modeling the complexity of the human brain. Kurzweil’s vision of a technological singularity can be understood differently, by looking at something Asimov wrote called “The relativity of wrong.” The general gist of the piece is that, no matter how wrong we are about things now, we’ll never be that wrong again. Another way of saying it is that progress builds upon itself; we don’t unlearn innovations we’ve made, which means that the pace of history inevitably accelerates through time. Every new idea comes into being in the presence of all the old ones, which means that the pool of information never shrinks.

So, while we’re running around chasing longevity, how do we make sure we get more Guinan and less Lady Cassandra?

My personal feeling here is that sure, we’ll get a set of interventions and therapies that can cut down on the vast majority of things that cause aging: the first five sigmas, as it were. But as we do that, things will likely become progressively weirder. Gene products don’t always do just the one thing; the phenomenon is called pleiotropy, whereby one segment of DNA does more than one important but unrelated thing. Crystallins are a good example of this — when expressed at low levels in body tissues, they act as enzymes, but when expressed at high levels in the eye, instead of being enzymatically active, they pack closely and form lenses. Meddling with a gene product is going to be a dicey proposition at best.

The bottom line is that humanity’s use of technology has the potential to be at least as constructive as it can be destructive, and navigating the line between those states will require a degree of knowledge orders of magnitude beyond what we have now. In theory, it should be possible to build supercomputers with enough raw processing power to simulate the human brain within a decade. Even if this occurs, however, it’s only the first step. The challenge from that point will be how to simulate a human brain, and to discover whether or not said simulation is capable of anything like human learning or cognitive processes. The question of sapience and consciousness and our ethical obligations in the event that these should occur is an entirely different can of worms.

The singularity, when and if it occurs, is unlikely to be anything like we’ve imagined, and the gulf between where we are today and where we’d need to be is too enormous to speculate on either its timeline or its properties. There are still too many things we know we don’t know and undoubtedly many that we don’t know we don’t know — to speculate on what form the singularity might assume. Mice trials and gene therapy are a long way from the quantum leaps Kurzweil believes the human race will take in the not-too-distant future. But they’re the only way to ensure that the future he and others want to create is worth living in, rather than the cyber dystopia that could occur if appropriate ethical guidelines and safeguards are not observed.

Read the rest of our Medical Tech Week stories for more. And be sure to check out our ExtremeTech Explains series for more in-depth coverage of today’s hottest tech topics.