Overcoming Population Arguments to Living Longer

Most people have not caught up to demographic reality

Those of us aiming to live past the point where aging is conquered look forward to a long future. Whether we hope to survive long enough to beat the aging process or whether we hope to be revived from cryopreservation, we hope and expect to be around many decades from now. For over half a century, one of the main objections we have heard is that the world is overpopulated and will become much more so. In several articles, I have shown that we are not overpopulated and that life tends to get better over time.

Is overpopulation something we should worry about for the rest of this century and beyond? My answer is no. First of all, more people are not inherently a problem. Each new person comes not just with a mouth to feed but with hands and brains to create and produce. So long as they are not prevented from using their hands and brains, additional people are a positive, not a negative. As economist Julian L. Simon wrote: “The world’s problem is not too many people, but lack of political and economic freedom.”

Second, even if more people were a problem, that does not justify preventing us from living longer. Third, fears of rapid population growth are badly outdated. [Ehrlich, 1990] Global population growth has been slowing for decades and total global population is projected to peak between the mid-2060s and the 2080s. The population of most developed countries is expected to fall well before then, the only exceptions being countries benefiting from plenty of immigration. Finally, to the extent that we should worry about too many people, we should be far more concerned about birth rates than death rates.

Values first

Let us pretend for a moment that population growth is or will become a serious problem. Would this give us a strong reason for opposing the extension of the human lifespan? No. Opposing extended life because eventually it might add to existing problems would be an ethically irresponsible response. Suppose you are a doctor faced with a child suffering from pneumonia. Would you refuse to cure the child because she would then be well enough to run around and step on the toes of others?

On the contrary, our responsibility lies in striving to live long and vitally and helping others do the same. The more progress we make on this primary goal, the more we can focus our energy on solving other challenges. Long, vital living at the individual level certainly benefits from a healthy physical and social environment. The superlongevity advocate would want to help find solutions to any population issues. But dying is not a responsible or healthy way to solve anything.

If we are to take seriously the idea of limiting lifespan so as to control population, why not be more proactive about it? Why not drastically reduce access to currently commonplace medical treatments? Why not painlessly execute anyone reaching the age of 70? (This would be “retirement” in the sense of the classic SF movie Blade Runner.) Once the collective goal of population growth is accepted as overriding individual choices, it is hard to resist this logic. Some radical green groups have indeed gone the whole way and accepted this result.

Fertility, not longevity, matters

Limiting population growth by opposing life extension not only fails the ethical test, it also fails the pragmatic test. Keeping the death rate up simply is not an effective way of slowing population growth. Population growth depends far more on how many children families have than on how long people live. In mathematical terms, longer life has no effect on the exponential growth rate. It only affects the constant of the equation. This means that it matters little how long we live after we have reproduced.

Compare two societies: In country A, people live on average only to 40 years of age, each family producing 5 children. In country B, the lifespan is 90 years but couples have 4 children. Despite the much longer life span in country B, their population growth rate will be much lower than that of country A. It makes little difference over the long term how many years people live after they have had children. The population growth rate is determined by how many children we have, not how long we live.

For the United States (whose population grows faster than Europe), the bottom line was summed in a presentation to the President’s Council on Bioethics by Biodemographer S. Jay Olshansky: 

If we achieved literal immortality today, the growth rate of the population would be less than what we observed during the post-World War II baby boom.

If we achieved literal immortality today, in other words, if the death rate went down to zero, then the growth rate would be defined by the birth rate. The birth rate would be about 15 per thousand, which means the doubling time would be 53 years, and more realistically, if we achieved immortality, we might anticipate a reduction in the birth rate to roughly ten per thousand, in which case the doubling time would be about 80 years. The bottom line is, is that if we achieved immortality today, the growth rate of the population would be less than what we observed during the post-World War II baby boom.

[Olshansky, 2002]

Olshansky and his colleagues also calculated the effect on life expectancy at birth from eliminating various diseases. A cure for cancer would increase life expectancy by about 3.5 years. About the same for elimination of heart disease. If we eliminated all cardiovascular diseases, diabetes and all forms of cancer, life expectancy at birth in humans would reach about 90. Olshansky argues that tackling aging would yield greater life expectancy benefits than tackling these diseases one-by-one.

Biodemographers Leonid Gavrilov and Natalia Gavrilova conducted a sophisticated analysis of the effects of longer lifespans on total population. Using Swedish demographic data due to its detail and history, they showed that population effects would be minimal to modest, depending on the specific scenario. Their starting point was a 2005 population of 9 million. Without any intervention, population would fall by one-third by 2105. In “Demographic Consequences of Defeating Aging” [Gavrilov & Gavrilova, 2010], the researchers consider four main scenarios:

1. Negligible senescence after age 60. Median lifespan increases from 84 to 134 years for men and from 88 to 180 years for women but after 100 years the Swedish population would increase by only 22%.

2. Negligible senescence for 10% of the population. Population declines by 28%.

3. Negligible senescence for 10% of the population with growing acceptance leading to 1% added to the negligible senescence group each year and the last 5% refusing these technologies. Instead of a decline from 9 million to 6 million by 210, the population would decline to about 7.9 million. Population declines by 13.5%.

4. Mortality continues to decline after age 60 years down to the levels observed at age 10, and then remaining constant. The population grows by 22% by 2105. If rejuvenation starts at 40 instead of 60, the population will grow by 47%.

The researchers note that the Swedish situation of 2010 reflects the current situation of most advanced nations today. “These numbers suggest that we should not hesitate to push for quite radical extensions of healthy human life span.” Extension of healthy lifespan would help to prevent a demographic catastrophe.

Global population growth ending

All projections of the population in 2100 or any year decades from now are estimates based on specified assumptions. Past projections by the UN have been reasonably accurate although they have mostly been revised down over time. The three main sources of future population estimates are the United Nations Population Division; the Wittgenstein Centre in Austria; and the Institute for Health Metrics and Evaluation at Washington University. They each use a distinctive methodology, the second and third being more sophisticated than the UN’s. They each also provide different projections by varying assumptions such as (most crucially) fertility rates. I will skip the details and summarize the findings of each.

UN Population Division: According to the World Population Prospects 2022, the world’s population is projected to reach a peak of around 10.4 billion people during the 2080s and to fall to 10.35 billion by 2100. The UN report also notes that, today, two-thirds of the global population lives in a country or area where lifetime fertility is below 2.1 births per woman (also known as replacement fertility). The number of people under 25 peaks in the 2030s.

The Wittgenstein Centre: Wolfgang Lutz and colleagues combine expert opinion and statistical modeling. This group uses a more sophisticated model of fertility and life expectancy compared to the UN. A major difference in outcomes results from the Lutz groups’ assumption that fertility will continue to fall in sub-Saharan Africa at a similar rate to recent years, whereas the UN assumes a slowdown in that decline. The Wittgenstein Center also assumes, based on expert opinion, that the fertility rate in low fertility countries will converge to 1.75 births per woman, but that this will not be until 2200 (rather than by 2100 as assumed by the UN).

In the Centre’s Medium (SSP2) scenario, world population would continue to increase until around 2070-2080 when it would reach a maximum level of around 9.8 billion before starting a slow decline, reaching about 9.5 billion by the end of the century. [Lutz, 2018 & 2108b] If more rapid social development is assumed world population would peak in 2055-2060 at 8.9 billion and decline to 7.8 billion by 2100. With lower female education and higher fertility rates, world population would reach 13.4 billion in 2100.

The fertility rate is affected by major factors. Factors increasing fertility include immigration from higher fertility countries increasing flexibility in work practices, public childcare provision, and local family policies. Factors decreasing fertility include increasing uncertainty in individual life-course planning, expanded education, higher cost of raising children, and acceptance of voluntary childlessness.

Between the pessimist and the optimistic educational scenarios, the difference in population size by 2060 is over one billion (9.8 vs. 8.9 billion).

In 2010, 117 countries had fertility rates above the replacement level of 2.1. The Center’s medium projection finds that there will be only 71 in 2030, 43 in 2050, and 17 in 2060. Of those latter 17, only 5 will have a fertility rate above 2.5. Almost half of the global population now lives in regions with below replacement fertility.

Europe (EU-28) will reach a maximum of 512 million by about 2035. Eastern Europe will lose about 10% of its population. China’s population will be 200 million lower in 2060 than in 2016. India’s population will be 31% larger. Most of the growth in population will come from Africa and India.

The Institute for Health Metrics and Evaluation (IHME): The IHME study improves on the UNPD and Wittgenstein forecasts in seven ways. Those seven include better modeling of fertility, the effects of educational attainment, mortality, and migration. [Vollset, 2020] This produced a 2100 global population forecast lower than the Wittgenstein Centre forecast and much lower than the UNPD forecast. The most likely trajectory for world population is a peak just after mid-century and a substantial decline by 2100.

A third of the difference is due to faster reductions in sub-Saharan African fertility and two thirds due to the lower level of fertility expected in populations with below-replacement fertility levels, particularly China and India. Some countries with below-replacement level fertility, including the USA, Australia, and Canada are likely to maintain working age population due to net immigration.

Table adapted from “Population and total fertility rate in 2017, in 2100 with the reference scenario, and in 2100 with the SDG pace scenario and the year of peak population.” IHME.

In the most likely scenario, the five largest countries in 2100 would be India, Nigeria, China, the United States, and Pakistan. However, these are not on the same path. Nigeria is expected to continue growing through 2100 but China and India are expected to peak before 2050 and then decline steeply. (More recent numbers suggest that China may have peaked already.) By 2100, China would be down to 51.1% of its peak population and India to 68.1% of its peak. The USA is projected grow its population until mid-century and then decline by less than 10% of the peak by 2100.

Like Japan in the 1980s, many people in the US have worried about the rise of China. The economic rise of China was driven in part by the movement of people from agriculture to the cities. But now that shift is slowing and the fertility rate has plummeted. Many people point to the one-child policy as an example of effective (too effective) central planning. In fact, the one-child policy was introduced in 1978-80, after fertility had declined from 6 to less than 3. So, it truly is a good example of central planning – and its failure. Current attempts to reverse the trends are failing.

The Africa wild card

Projections for the developed world can be made with considerably more confidence than those for Africa. You can see this in the difference between the UN and University of Washington projections, with the former expecting almost a tripling of Africa’s population by 2100 and the latter only a doubling. The IHME projects also show a wide range of outcomes depending on various factors affecting fertility.

We do not know yet whether fertility rates in Africa will follow those in the rest of the world. The UW projections see Africa reaching a fertility rate below 2 by the 2070s under the medium assumptions. Population panickers seem to be unaware of how rapidly fertility rates have fallen since the peak in the late 1960s.

The next most populous country today is India. Its population is projected to grow until mid-century. This coming reversal is highly likely given that the number of children in India peaked more than a decade ago and is now falling.

Going down

Despite their differing models and projections, the three major forecasters all see global population growth slowing and the population aging by the end of this century. The Wittgenstein Centre, the Washington University researchers differ from the UNPD in expecting global population to age faster, peak sooner and then decline faster. Some other conclusions from the IHME projections:

• By 2100, fertility will fall below the level required to maintain population in 183 out of 195 countries. This would change only if those countries adopted more open immigration policies. However, obviously more migration cannot affect the world population.

• Global population will peak in 2064 at around 9.7 billion people and then decline to 8.8 billion by 2100.

• 23 countries, including Japan, Italy, Spain, Portugal, and Thailand, will experience a population decrease of more than 50% by 2100.

• Countries whose population will shrink by 25% to 50% include China. Many of the countries with the fastest-shrinking population will be in Asia and eastern Europe.

• Working age populations will shrink faster than total population in countries such as China and India, with major economic implications.

• The combined population of Europe (excluding the UK), China, Russia, Japan, South Korea, and Taiwan will start falling before 2030.

• Even with an assumed increase in fertility rates, the populations of China, the EU, Russia, and Japan will decline sooner and more rapidly than the USA. Thanks to higher net migration, the population of the USA is projected to keep growing for another half century despite its below-replacement fertility rate.

Causes of slowing population growth

Unfortunately, a peak and then falling population looks inevitable in a world lacking dramatic life extension. Numerous factors are conspiring to depress fertility and therefore population. Population aging reduces fertility by reducing the number of potential mothers. In developing countries, children shift from being producers to being consumers. Raising children becomes increasingly expensive. Ideal family size is shrinking as it is linked to the smaller family size of earlier cohorts. Higher incomes and educational levels lead to delayed or canceled childbearing.

Economic challenges of declining population

With a growing population comes a growing market, more specialization and division of labor (a key driver of productivity), and more innovation. Governments can reduce or prevent these benefits through constant war and by failing to protect property rights. So long as sufficient legal and cultural protections exist, a growing population will generate these vital benefits. [Simon, 1990; 1997; 2019]

Must a falling population therefore suffer decreasing wealth, well-being, and opportunity? We have relatively little experience of gradually falling populations and the economic outcomes. Most major reductions in population historically have been sharp and severe, resulting from war, disease, or mass starvation. A more gradual and predictable decline should be more manageable. Even so, there are clear downsides, at least assuming similar economic policies as those existing today.

More economically significant than a shrinking total population is a reduction in the working age population. The “dependency ratio” is the ratio between people defined as dependents (under-15s and over-65s) and working-age people. In countries such as Nigeria, the dependency ratio is projected to fall through the end of this century. This means the country’s working population has fewer people to support potentially resulting in more rapid economic growth, an effect called the “demographic dividend”. The full extent of this dividend is not automatic. In India the dependency ratio fell from almost 80% in 1970 to less than 50% today but it failed to enjoy the full benefits because deficiencies in education and health in addition to poor job creation has limited growth in the labor market.

In many of the more advanced economies, the dependency ratio is projected to rise throughout this century. This will be a major issue in Europe and more so in China.  You can see this especially vividly in Japan:

In Japan, as in most advanced nations, the demographic over 65 will grow. Since the youthful group is not expected to change significantly, the working age demographic will shrink. For each person of working age, more will be spent on medical and retirement expenses. This may be paid partly by higher taxation with its growth-suppressing effects, or by increased borrowing which can increase inflation and raise the cost of capital, thereby slowing growth with all its benefits.

If people enjoyed more years of healthy life, the dependency ratio would be held down. A rapid enough increase in healthy lifespan would enable societies to thrive despite static or declining populations.

Also, speculatively but increasingly plausibly, artificial general intelligence (AGI) may help to compensate for a shrinking working age population. This could help not only with taking the place of unavailable workers but in taking care of older, infirm people. Japan is investing heavily in robotics to this end.

The imperative to further extend the human life span

Even if there were a population problem in a few countries, extending the human life span would worsen the problem no more than would improving automobile safety or worker safety, or reducing violent crime. Who would want to keep these deadly threats high in order to combat population growth? If we want to slow population growth, we should focus on reducing births, not on raising or maintaining deaths. If we want to reduce births, we might voluntarily fund programs to provide contraceptives and family planning to couples in poorer countries. This will aid the natural developmental process of choosing to have fewer children.

Consider, also, that with a very high probability, the first truly effective technologies to extend the maximum human life span will come with a significant cost of development and application. Population effects would first be felt, therefore, in the developed countries where populations are already peaking or declining. This highlights the falsity of the idea that extended lifespans would dramatically increase population. Increased longevity would have little effect on global population, especially considering the small and falling share of the global population accounted for by the developed nations.

As we have seen, the world does not have a problem of too many people now or in the future. The real problem is a static and declining population that is aging and infirm. Investment in life extending measures would therefore have a massive payoff economically in addition to saving lives. A 2008 McKinsey Global Institute study titled “Why the Baby Boomers Will Need to Work Longer” pointed out that “A two-year increase in the median retirement age over the next decade would add almost $13 trillion to real US GDP during the next 30 years.” [Beinhocker, 2008]

Suppose that we were to eliminate major diseases including heart disease, cancer, and stroke. Demographers have calculated that eliminating cancer would increase life expectancy at birth by only about 3.5 years. A cure for heart disease would have a similar effect. If you do not die of one thing, you will die of something else. It turns out that if you eliminated all cardiovascular diseases, diabetes, and all forms of cancer together, life expectancy at birth in humans would rise from just over 72 globally or 77.2 in the USA (2021) to about 90. That’s a welcome but surprisingly modest increase. [Goldman, 2013; [Olshansky, 2002]

The same researchers, using the Future Elderly Model, found that if we delayed aging and increased life expectancy by 2.2 years of mostly good health, the increase in economic value would be $7.1 trillion (2010 dollars) over 50 years. Imagine the benefits from 10, 20, or 50 extra years of good health. By contrast, tackling heart disease or cancer separately produces diminishing improvements in health and lifespan by 2060 primarily because of exchanging one risk for another.

Simply extending healthy lifespans without making any other changes will produce massive benefits but also massive costs, as shown below. That would be an unrealistic scenario given that we have already responded to longer lives by delaying the retirement age. (Well, not in France.) The green line in the chart shows the effect on major entitlement spending of a 2.2 year extension in life while adjusting eligibility for tax-funded benefits. That chart concerns only entitlement spending and does not include the enormous benefits of increased economic output.

Chart from Goldman, 2003.

Remember the study by Gavrilov and Gavrilova: They concluded that even in the event of a successful biomedical triumph over aging, “population changes are surprisingly slow in their response to a dramatic life extension.” Their modest life extension scenarios still led to a declining population. Even the more radical scenarios increased population only modestly and that only happens by unrealistically assuming that every person in the country adopts anti-aging technologies. If some reject these technologies for reasons of religion, inconvenience, non-compliance, fear of side effects, or costs, the total population could still decline over time.

For the United States (whose population grows faster than Europe), the bottom line was summed in a presentation to the President’s Council on Bioethics by S.J. Olshansky. In his scenario, the death rate went down to zero while the birth rate started at about 15 per thousand and declined to 10 per thousand. “The bottom line is that if we achieved immortality today, the growth rate of the population would be less than what we observed during the post-World War II baby boom.” This would mean a doubling time of 80 years. [Olshansky, 2002]

I have been writing on the topic of population trajectories for over 40 years. [More, 1978, 1997, 2004, 2014] The typical view I have encountered has remained stubbornly unchanged in that time – even as it becomes increasingly distant from the current reality and the most plausible projections. I see a confusion of population with problems created by corruption, authoritarianism, economic ignorance and mismanagement, and warfare.

The confused population-based objection to life extension and cryonics is our perennial enemy. Let us continue to overcome that enemy with informed persuasion. Once the enemy belief vacates the minds it occupies, more people will be open to accepting and supporting our desire to enable everyone to live much longer, healthier lives.

References

Beinhocker, Eric, Diane Farrell, Ezra Greenberg, “Why the Baby Boomers Will Need to Work Longer.” McKinsey Quarterly, 1 November 2008.

Paul R. Ehrlich & Anne H. Ehrlich, The Population Explosion (New York: Simon and Schuster, 1990).

Gavrilov, Leonid A., Natalia S. Gavrilova (2010), “Demographic Consequences of Defeating Aging.” Rejuvenation Research. 2010 Apr; 13(2-3): 329–334.

Goldman, D.P., Cutler, D., Rowe, J.W., Michaud, P.C., Sullivan, J., Peneva, D., Olshansky, S.J. (2013), “Substantial health and economic returns from delayed aging may warrant a new focus for medical research.” Health Affairs 32(10):1698-1705.

Lutz, Wolfgang, Anne Goujon, Samir KC, Marcin Stonawski, Nikolaos Stilianakis (Eds.) (2018), Demographic and human capital scenarios for the 21st century 2018 assessment for 201 countries.

Lutz, Wolfgang, William P. Butz, Samir KC, (2018b), “World Population & Human Capital in the Twenty-First Century” executive summary.

https://pure.iiasa.ac.at/id/eprint/11189/1/XO-14-031.pdf

More, Max (2014), “Longer Lives on the Brink of Global Population Contraction: A Report from 2040” in The End of the Beginning: Life, Society and Economy on the Brink of the Singularity. Humanity+ Press; 1st edition (July 9, 2015)

More, Max (2004), “Superlongevity without Overpopulation”, chapter in The Scientific Conquest of Death. (Immortality Institute, October 2004.) Also in Fight Aging.

More, Max (1997), “Life Extension and Overpopulation”, Cryonics, first quarter 1997.

More, Max (1978), “Population Problems” in The Absolute.

Olshansky, S.J. (2002) “Duration of Life: Is There a Biological Warranty Period?” The President’s Council on Bioethics, Washington, DC.  

https://bioethicsarchive.georgetown.edu/pcbe/transcripts/dec02/session2.html

Carnes, Bruce A, S Jay Olshansky, Douglas Grahn (2003), “Biological evidence for limits to the duration of life.” Biogerontology, 2003;4(1):31-45.

Simon, Julian L. (1990), Population Matters. New Brunswick, N.J.: Transaction.

Simon, Julian L. (1997), Research in Population Economics. Princeton, 1997.

Simon, Julian L. (2019), The Economics of Population Growth. Princeton University Press.

Population by Age Group, including UN projections, World

Based on medium fertility scenario

https://ourworldindata.org/grapher/historic-and-un-pop-projections-by-age?time=1950..2100

Vollset, Stein Emil, Emily Goren, Chun-Wei Yuan, Jackie Cao, Amanda E Smith, Thomas Hsiao, et al. (2020), “Fertility, mortality, migration, and population scenarios for 195 countries and territories from 2017 to 2100: a forecasting analysis for the Global Burden of Disease Study.” The Lancet, July 14, 2020.