My essay, overpopulation is a non-issue for radical life extension:
One of the most common objections against the prospect of radical life extension (RLE) is that of overpopulation. Suppose everyone got to enjoy from an eternal physical youth, free from age-related decay. No doubt people would want to have children regardless. With far more births than deaths, wouldn't the Earth quickly become overpopulated?
There are at least two possible ways of avoiding this fate. The first is simply having children later. Even if nobody died of aging, there would still be diseases, accidents and murders. People who've looked at the statistics estimate that with no age-related death, people would on average live to be a thousand before meeting their fate in some way. Theoretically, if everyone just waited to be a thousand before having any kids, then population growth would remain on the same level as it is today.
Of course, this is completely unrealistic. Most people aren't going to wait until they are a thousand to have kids. But they might still have them considerably later than they do now. The average age for having your first child has already gone up as lifespans have grown. If you're going to live for a thousand years, why rush with having kids as soon as possible?
Currently there is (at least for women) an effective maximum cap on how high the age for first childbirth can grow, since once a mother's age grows beyond 35 or so, the probability for birth defects goes up radically. However, current reproductive technology has already made pregnancies over the age of 50 a real possibility. At the moment, this frequently requires egg donation, but a rudimentary ability to produce eggs from stem cells may not be that far away, certainly a lot closer than RLE. By the point that we have RLE, we'll likely also have the ability to produce new sperm and eggs from a person's own cells. Combined with an overall better condition of the body brought about by RLE, this seems like it could increase the maximum age for pregnancy indefinitely. With that, the average age for a first birth going up at least a couple of decades doesn't seem all that unrealistic.
Besides the average age for having kids going up, there's the possibility of larger family groups. Must we necessarily have a norm for children being the kids of exactly two adults? As a personal example, my best friend has a daughter who's two years old right now. I've been over there helping take care of the girl a lot, enough to make me feel like she's part of my family as well. Even if I never had children of my own, I already feel something resembling the feelings related to having a child of your own. In addition to growing attached to the children of your close friends, polyamory is also gradually becoming more common and accepted. With romantic relationships involving more than two people we also get children with more than two parent-like figures. Many have a strong desire to pass on their genes, something which can be helped with e.g. the recent creation of 3-parent human embryos.
So with both the prospect of having kids later and a child having more than two parents, I really don't think that the population problem is as hard to solve as some people make it out to be. It should also be noted that it's not like scientists are going to develop RLE one day, and then the next, blam, everyone lives forever. Rather, the technology will be developed in stages. In the early stages, there are going to be a lot of people who have grown far too frail to be helped, and it might take a long time before we hit acturial escape velocity, so there might simply be an e.g. 10-year bump on people's lifespan and then 20 years could pass before the next major breakthrough.
The treatments may also not be affordable for everyone at first, though it needs to be noted that governments will have a huge incentive to subsidize the treatements for everyone to reduce the healthcare costs of the elderly and to push back the age for retirement. A 2006 article in The Scientist argues that simply slowing aging by seven years would produce large enough of an economic benefit to justify the US investing three billion dollars annually to this research. The commonly heard "but only the rich could live forever" argument against RLE does not, I feel, take into account the actual economic realities (amusingly enough, as its supporters no doubt think they're the economically realistic ones).
So we're going to get a slowly and gradually lengthening average lifespan, which at first probably won't do much more than reverse the population decline that will hit a lot of Western countries soon. The replenishment rate required to keep a population stable is about 2.1 children per woman. The average fertility rate in a lot of industrialized countries is well below this - for instance, 1.58 in Canada, 1.42 in Germany, 1.32 in Italy, 1.20 in Japan and 1.04 in Hong Kong. The EU average is 1.51. Yes, in a lot of poor countries the figures are considerably higher - Niger tops the chart with 7.68 children per woman - but even then the overall world population growth is projected to start declining around 2050 or so.
To give a sense of proportion: suppose that tomorrow, we developed literal immortality and made it instantly available for everyone, so that the death rate would drop to zero in a day, with no adjustment to the birth rate. Even if this completely unrealistic scenario were to take place, the overall US population growth would still only be about half of what it was during the height of the 1950s baby boom! Even in such a completely, utterly unrealistic scenario, it would still take around 53 years for the US population to double - assuming no compensating drop in birth rates in that whole time.
We've adapted to increasing lifespans before. Between 1950 and 1990, the percentage of population over 65 almost doubled in Sweden, going from 10.3 to 18.1. (In the United Kingdom it went up from 10.7 to 15.2, in the US from 8.1 to 12.6, and in the more-developed countries overall it went from 7.6 to 12.1.) The beauty of economics is that like all resource consumption, having children is a self-regulating mechanism: if a growing population really does exert a heavy strain on resources, then it will become more expensive to have children, and people will have less of them. The exception is in the less industrialized countries where children are still a net economic benefit for their parents and not a cost, but most of the world is industrializing quickly. Over the last fifty years, the gaps between the rich and poor have gotten smaller and smaller, to the point where people are calling the whole concept of a first world/third world divide a myth. I see no reason to presume that radical life extension and indefinite youths would pose us any problems that we couldn't handle, at least not on the overpopulation front.
For anyone curious, this was mostly an English recap of some of the life extension-related discussion I covered in my 2009 book Kehittyvä ihmiskunta. If you can't read Finnish but were wondering what I wrote in that book, well, now you know a bit.
Periodically in discussions of cryonics and related issues, people bring up "the overpopulation argument, and the counterarguments that respond to it" without actually describing those arguments in detail. Overpopulation was a big concern of mine prior to exposure to anti-deathism. And so far, it still is. I have no philosophical problem with eliminating death, but it seems to me that getting rid of death BEFORE we eliminate all the other major problems facing humanity is going to make those problems much worse. Death is an enemy that should be vanquished, but it's not an enemy I'm prepared to destroy until I'm satisfied that we'll be able to handle the consequences.
If death is solved via uploads running at high speed, I'm not too concerned. (Still a little concerned, since computers still take up space, but the issue is close enough to negligible that I'm fine ignoring it).
If we're dealing with physical humans taking up physical space requiring physical resources, then I'm worried. Either we're growing exponentially, or we've eliminated childbirth, or we have strict rules in place about people who have children being willing to die. (The latter might work but modifying central aspects of the human life cycle that we are hard-wired to value seems.... challenging, to say the least)
The sense of I've gotten around here is that "exponential growth is okay, because Space is Big". Space certainly is big, and I imagine we could expand for a long time without running into conflict. But if there's even one other alien race who solves their problems the same way (expanding whenever they run out of space or resources), then eventually there's going to be conflict. And the longer we go BEFORE that conflict, the more human suffering it might entail. I'd prefer to have achieved equilibrium as a species beforehand.
I want to expand into the universe, but I think we should do so out of *curiosity* rather than *necessity.*
I assume there's been a lot of discussions about this and I don't want to rehash them. But if someone could summarize the issues at hand and explain what the community consensus is, I'd appreciate it. ("Community Consensus" might mean "there are a few dominant schools of thought here").
Edit: FAWS pointed out that as long as, on average, each person reproduces slightly less than once, growth will not continue exponentially. That's pretty much the answer I'm looking for. The logistics are still significant, but in the long run I think such a law would be enforcible. (Each person only gets to reproduce once, and some people will choose not to. I think there'd need to be an additional disincentive, because over the course of an immortal lifespan, people are likely to try out childrearing at *some* point).
I still think that the issues surrounding overpopulation should occupy at least as much of our attention as ending death (basically ensuring that people are given adequate resources to live healthy, productive lives).