Suppose that the medicine genie appears out of a lamp and announces that all humans are now immortal. What happens next?
By “immortal” I mean all diseases cured and the aging problem fixed. (And, since I’m in control of the hypothetical, the genie means the same thing. Controlling ridiculously powerful fictional beings is fun.) This would therefore remove all natural causes of death. Murder, suicide, and accident would not be affected by mere immortality, and everyone would still require a habitable planet. It’s that bit that’s probably the issue.
This requires figuring out how many people the Earth can support. The genie wouldn’t think of that because for most of history it never came up, and recently he hasn’t been paying much attention to anything other than the inside of that lamp. The number of people the Earth can support isn’t constant, but it isn’t infinite either. And nobody knows what it is. Check page 31 of here for a description of how nobody can agree. But the median estimate (insofar as that means anything) is about 10 billion. Beyond that, it’s impossible to produce enough to support more people, and people starve no matter how food gets distributed. Well, beyond whatever the true value is. Which nobody knows. People can’t even agree on whether or not we’re past it. I’ll use ten billion because I need a number, but keep in mind that estimates range from one to one thousand billion. Math based on guesses: Not fun. My hypothesis is that the genie made sure nobody agreed specifically because he wanted to mess with my math.
Right now, it’s estimated that human population will reach that point at approximately 2100. But that’s assuming the real world, where people die too often. If that problem gets magically taken away, it happens quicker. By my math, it takes…wow. Less than nineteen years. OK, so the human race has less than two decades to do something.
Assume the accidental death rate is constant at thirty-six fatalities per 100,000 per year. (It probably won’t be, of course, if people act more careful around potential accidents when they realize that “you only live once” is even stupider than usual. But statistics on immortal populations are a bit hard to come by.) In this case, the median immortal human would live for about 1925 years, with an average of over 2700. Ninety-five percent would live past 140, and two or three percent could live as long as human history so far. Basically, the human lifespan would increase to…eight and a half…carry the three…a very long time.
There are a few things people can do to help fix the problem. Norman Borlaug developed a better version of wheat that singlehandedly increased Earth’s carrying capacity by over a billion. (And what did you do today?) That kind of thing can buy some time. And of course birth rates would drop precipitously, so there are more than 19 years to prepare.
The first thing that happens when everyone notices that everyone is suddenly young and healthy is large amounts of celebration. By the time that’s over, plenty of people have figured out all the possible side effects. Suddenly all policy makers go into overpopulation-crisis mode. (Do they have an overpopulation-crisis mode? Probably. Most likely it just consists of frantically trying anything that sounds like it might help.) Anywhere with legal limits on family size starts enforcing them as much as possible, more countries add them, and any jurisdiction that pays people to have children will obviously stop. Birth control gets made as available as possible, and the tax on cigarettes gets repealed.
Some people decide to reduce the population by direct means, and start killing indiscriminately. After murdering way too many people, they have still had no statistically significant effect on world population, but they get a lot of publicity and are soon stopped by the inevitably heightened security measures.
The vastly decreased need for health care frees up resources to work on fixing the current problem, so they can soften the blow as much as possible. Funding increases for things like colonization of Antarctica and space travel, neither of which actually helps anything in the near term, but I’m not about to argue. We should have been doing more cool stuff earlier anyway.
In two decades, maybe more, the resource crisis hits. People starve. There’s no extinction threat, but it is the worst event of its kind ever. It’s a worldwide emergency, and by the time it ends the population has been forced to stop multiplying so much. This will happen again every few thousand years unless people start learning from history.
By the end of the most chaotic century in history, the world stabilizes, probably more than 2013 people would like. Progress (in every arena) slows dramatically down now that “finish in my lifetime” is no longer an urgent goal. On the other hand, “I’ll be dead by then” is no longer a reason for not caring about something. Long-term plans suddenly become significantly more existent.
The final outcome isn’t utopian, but it’s not terrible either. And the genie did fix the whole bounded lifespan problem. Not bad considering everyone was totally unprepared.