What if we could slow down human aging, stay young longer, and live far longer than we do now? This is called life extension, and scientists and investors are starting to take it seriously.
The National Institutes of Health in Washington D.C. has a GeroScience Interest Group for life extension; they say “a slower rate of aging leads to an increase in health span, the ultimate goal of biomedical research.” The private sector is taking notice: in 2013, Google founded a company called Calico to develop life extension methods, backed by $2.5 billion, and they’ve since invested more and partnered with pharmaceutical giant AbbVie.
How long might we live? Among scientists who consider life extension possible, some say we might extend our life expectancy to 120 years. Some say it could be much longer. Prominent geroscientist Steven Austad said in Scientific American that the first baby to live to be 150 years old had already been born by the year 2000. Of course, if we can slow aging, it’s conceivable that we could slow it to a halt, or perhaps even reverse it. A small study recently reported in Aging Cell (and here at ORBITER) claims to have reversed aging by 2.5 years using a growth hormone and two diabetes medications.
Endless youth is an ancient dream, but surveys from the Pew Research Center and various universities show that a majority of people don’t want it, and many of them don’t want anyone else to have it either. Broadly speaking, there are three concerns. First, many people think extended life would become boring, meaningless, or otherwise undesirable. Second, there are issues of justice: what if only the rich and powerful get it? Third, there is a concern that life extension might cause severe overpopulation, partly because people have more time to have more babies, and partly because everyone is living longer. I’ve written a book about all three issues, but I’ll focus here on overpopulation.
It’s a widespread concern. Philosopher Peter Singer, for example, thinks life extension would be a bad thing, for there would “soon be more people than the world can support.” Many others agree; two-thirds of those in a recent Pew survey about attitudes toward life extension said they’re worried about this.
But not everyone is convinced that life extension will cause a population crisis. Some say that new technologies will bring us clean, infinite energy and an abundance of food. Some say we’ll colonize other planets. (Adam Frank casts doubt on that idea in this 13.8 blog entry.) Some say we needn’t worry because birthrates are falling all over the world and the world’s population will start declining later in this century.
However, these scenarios are speculative. Moreover, we really can’t know what effect life extension will have on future population trends, for we don’t know how much longer people will live, or what percentage of the human race will have life extension, or how many children they may choose to have.
And yet we can get a grip on this issue using projections. We can project what population trends would be if we assume a given life expectancy, number of people who have life extension, and number of children per woman, and then see how those variables affect population trends. To do this, I worked with a demographer, Shahin Davoudpour, to generate some projections for various assumed life expectancies and birthrates. (Our formula and projections appear in my book.) The results surprised us.
For example, right now the birthrate in many European countries is around 1.5 children per woman—so low that those populations will shrink over time. (The replacement fertility level is 2.1 children per woman.) But if a billion people who are having 1.5 children per woman also have life extension and—to use Austad’s prediction—they live an average of 150 years, that population will not shrink. Instead, it will triple in 125 years and then stabilize at 3 billion indefinitely, even though they’re not having any more children than before!
A glimpse of overpopulation
We can’t predict that this will happen, but we can be sure that this will happen in a population with that assumed life expectancy and birthrate. With longer life expectancy or higher birthrates, the problem gets much worse. For example, according to our projections, if people live an average of 150 years and have three children per woman, the population never stops increasing.
Davoudpour and I then asked this question: What birthrate would keep the population increase at a tolerable level? Let’s suppose we want to be sure that life extension doesn’t increase the world’s population by anything over a one-third increase. If people live an average of 150 years and have .5 children per woman (every other woman has one child), then the population will increase by one-third for a few generations, and then steadily decline thereafter. If you think that a one-third increase is not tolerable, then the birthrate would have to be even lower.
If life extension becomes widely available, severe overpopulation is almost inevitable, unless those who use life extension severely limit their birthrate.
To avoid this, the government would have to limit how many children you can have if you use life extension. I call this a policy of Forced Choice—you’re forced to choose between extending your lifespan and having as many children as you wish.
Is Forced Choice morally OK?
There are obvious enforcement issues. How does the government keep track of who has life extension and who does not, and how do we prevent people from having more children than they’re supposed to? But let’s set those questions aside, and ask a different kind of question: Is a policy like Forced Choice morally permissible?
China’s one-child policy (which was changed to a two-child policy in 2016) comes to mind. Many people believe such a policy is an unjust intrusion on very personal matters—an unacceptable violation of personal liberty. John Stuart Mill argued that people have something like a right to liberty, and that it’s wrong for anyone (including the government) to force them to act against their own choices, even when it’s done for their own good. But Mill also said that there’s a limit to respecting liberty. It’s called the harm principle, and it says that other people (including the government) may limit your liberty to prevent you from harming other people.
Is Forced Choice justified by the harm principle? By preventing a Malthusian catastrophe, we’d be protecting people from the harm of overpopulation (and protecting nonhuman living things, since harm to them counts too). You might think that people who extend their lives are just harming themselves, but it seems safe to assume that many others—those who either can’t afford life extension or just don’t want it—would also be harmed.
So the harm principle is one justification for imposing Forced Choice.
Another possible justification is that those who choose to use life extension have, in effect, consented to limiting their birthrate. After all, they had a choice between life extension with a limit on their reproduction, vs. a normal lifespan without that limit. They chose the option that includes that limit. None of them are forced to limit their reproduction; they’re just forced to make a choice.
But (they may protest), “We were forced to do something we didn’t want to do. We were forced to make that choice. We would have preferred to have life extension without having to make that choice, and have as many children as we want.” And being forced to choose is a violation of liberty—or so their argument might go.
Moreover (they may continue), “The harm principle protects us too. If you force us to choose between extending our lives and having as many children as we think best, we’ve been harmed by not getting what we most want. Therefore, the harm principle says that Forced Choice is unjust.”
Limits of the harm principle
Well, not so fast. If not getting what you want is a harm, then society can’t ever stop anyone from doing anything they want to do. The government can’t, for example, pass a law against drunk driving: it harms those who prefer to have a flask of whiskey in one hand while steering with the other. This, of course, is ridiculous.
Here’s another reason to think people aren’t harmed by being forced to choose between extended life and having as many children as they wish. A normal lifespan is natural, while an abnormally long lifespan is not. That’s not to say that there’s anything wrong with an unnaturally long lifespan. Many good things are not natural: eyeglasses, vaccines, movies, the internet. However, perhaps your right to treatments that help you live longer is limited to whatever medical help you need to enjoy in order to have a normal lifespan and prevent an early death.
If so, then your right to life doesn’t include a right to life extension, let alone a right to life extension while having as many children as you want.
If your rights aren’t violated, you aren’t harmed.
My take on all this is that imposing a reproductive limit on those who want extended life does not harm them, so their liberty right isn’t violated—therefore it’s morally permissible for the government to limit their reproduction.
But if I’m wrong, then we must ask which scenario contains more harm. In one scenario, people can have life extension with no limit on their reproduction, but there is a Malthusian crisis that gets worse and worse over time, thereby harming people who don’t have life extension. In the other scenario, the Malthusian crisis is prevented, but those who want more life and more children have to give up one thing or the other, thereby harming them.
So which is worse? A population crisis or frustrating the parental ambitions of those who want to live longer than anyone does now? If the National Institutes of Health, Google, and some bold geroscientists are right, we may need to address that question sooner than later.
John K. Davis is a professor of philosophy at Cal State Fullerton, where he specializes in applied ethics and publishes on issues raised by new and emerging technologies, particularly in the life sciences. In 2017 he published New Methuselahs: The Ethics of Life Extension (MIT Press), a book-length study of ethical issues raised by the prospect of life extension. He was a practicing attorney for 17 years before earning his PhD and specializing in bioethics.