"Thought experiment: It turns out that there is no single senescence "master switch", but there are three or four fairly simple genetic tweaks we can make (either via epigenetic modulation or by actual insertion of a handful of genes by way of a suitably customized virus) that (a) slow the ageing process in young adults by a factor of ten, and (b) partially reverse the ageing process in middle-aged or elderly adults so that after a few years or decades they recover physically to the equivalent of a 25-year-old. A vaccine is developed, becoming available some time between 2020 and 2030, which can be mass produced for roughly $5 a shot — one injection, and the recipient isn't going to die of cellular senescence. Note that there is some small print attached.I can't resist. A cheap inoculation that grants eternal youth. Eternal? Well, no, but almost a thousand years or so, which gives you a good chance (providing civilization keeps on chugging away), of someone further refining the technique towards near immortality.
(Small print: This is not a magic cure-all. It doesn't cure bacterial or viral infections, cancer, prion diseases, autoimmune diseases, diabetes, cardiovascular disease, or neurological conditions. It doesn't enable the user to regenerate lost limbs. It does enable stem cells in adult tissues to produce more new cells, improving recovery from injury and attrition due to age (such as damage to cardiac tissue or progressive loss of cortical matter in the brain). It does not preclude the development of other treatments for the above conditions.) What do you think the consequences are likely to be"?
Rereading the above, I think one thing - a very important thing - is left out of the small print.
Is this condition heritable?
Oh, I don't know, is it that important? You see, my short answer to what the consequences will be is easy:
The End of Humanity. Death by population implosion.
Whether the condition is heritable merely postpones the end a few hundred thousand years or so. Maybe I better backtrack...
Do I really need to list out the short-term consequences? I don't think they'll matter, but why not? They are the easiest to foresee.
So. Everyone gets a shot. I think everyone could scrape up five bucks to become immortal. Which means, we can no longer afford poor people. No more safety nets. No more retirement, unless you have a few hundred million socked away, and even then... some unfortunate stock crashes, and you'll have to work the rest of a very long life. Stock crashes? Guaranteed! Think of all the useless services and products once people are immorbid (which is to say, not immortal, but youthful, and therefore not frail, not feeble, not decrepit). You probably will wear out teeth. The dental industry is safe. As are emergency services. There will be HUGE influxes of monies into curative and preventative procedures for the thousand arrows flesh is heir to in the small print above. Nevertheless, there will be major financial calamities from having so many healthy people around.
Oh, that's right. Healthy people. Young healthy people. Horny young healthy people, who, now that they have their youth back, will want to be fucking. A lot. I'm sure worries about a population explosion are obvious, but I'm nonplussed about it. Given that this is an obvious thing to worry about, it will be addressed post-haste (we already worry about it). I would assume that draconian measures would be put into place. A replacement lottery, perhaps. Some type of meritocratic filter, perhaps. Doubtful, though for the idle rich. If you thought they are useless parasites now...
Speaking of draconian measures, what to do with all of these people? Are there enough jobs to go around? And will people, now cognizant that they may have centuries of life ahead of them if they cut down on the risky behavior, be willing to take on dirty and dangerous jobs? And what about the next generation? Will they have jobs? We barely have them now! Oh, you'll adventurers, surely, risk takers and thrill seekers. But will they inherit the planets, the stars? I kind of doubt there will be enough willing to go off-planet.
This future is not looking so hot. But I'm sure some type of quasi-stable dynamic equilibrium will be arrived at, to keep things going. Question is, once you have powerful immortals running things, keeping very close tabs on things, do you want to live in that world? You do now.
Regardless, attrition will occur. Accidents, cancers, plagues, strokes, heart attacks, forces of nature.
There's no reason to think that would keep the population down.
Ah, resource depletion. There's a problem. Not to mention you can always have a societal collapse. And when that happens, when immortals have to live under, say, 1st century BCE conditions, or 10,000 BCE conditions, I think inevitably you reach a point where there's fewer and fewer of us.
And if we head towards a bright and golden future? Technology and science keep on advancing? I've always maintain that a post-scarcity society is the best horror story of all. Simply because it is uncharted territory.
I can't see how you avoid a posthuman world. So, humans still disappear, as we augment ourselves past the hominid stage. Oh, you'll have some perverts and fetishists, the curious who will take a shot at trying out the human form, but the rest of us. Who knows what kind of monsters we will become?
But I'm betting finally, nothing lasts, we're done, we're gone, and thats the end of us.
I think I'll go find out what Charlie's scenario is...