The Scientific Conquest of Death: Essays on Infinite Lifespans, a book published by the Immortality Institute, examines many of the social as well as technological aspects of the future of healthy life extension. Max More's contribution to The Scientific Conquest of Death, reprinted here with permission, handily demonstrates that fear of overpopulation is not a legitimate objection to greatly extending the healthy human life span.
Copyright © Max More.
Proponents of superlongevity (indefinitely extended life spans) have been making their case for the possibility and desirability of this change in the human condition for decades. For just as long, those hearing the arguments for superlongevity have deployed two or three unchanging, unrelenting responses. The question: "But what would we do with all that time?" is one of them. Another is the "But death is natural!" gambit. The final predict-able response is to conjure up the specter of overpopulation. Despite strong downward trends in population growth since this issue gained visibility in the 1960's, the third concern remains an impediment.
Paul Ehrlich's 1968 bestseller, The Population Bomb , ignited a trend in which alarmists routinely ignored data and reasonable projections to scare the public. Those of us who see achieving the indefinite extension of the human life span as a central goal naturally find this behavior quite irritating. If baseless fear wins out, we will gain little from our personal programs of exercise, nutrition, or supplementation. Widespread fear leads to restrictive legislation - legislation that in this case could be deadly. Although the volume has been turned down a little on the population issue, it continues to reverberate and deserves a response. The purpose of this essay is to address the essential concerns, provide current facts, and dispel the errors behind the overpopulation worries.
As I will show, we have little reason to fear population growth with or without extended lives. However, to bring into focus an ethical issue, I will pretend for a moment that population growth is or will become a serious problem. Would this give us a strong reason for turning against the extension of 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 while helping others do the same. Once we are at work on this primary goal, we can focus more 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.
Besides, if we take seriously the idea of limiting life span so as to control population, why not be more proactive about it? Why not drastically reduce access to currently commonplace medical treatments? Why not execute anyone reaching the age of seventy? Once the collective goal of population growth is accepted as overriding individual choices, it would seem hard to resist this logic.
IT IS HOW MANY, NOT HOW LONG, THAT 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 popula-tion growth. Population growth depends far more on how many children families have, as opposed to how long people live. In mathematical terms, longer life has no effect on the exponential growth rate. It only affects a 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 life span 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.
Even the short-term upward effect on population due to a falling death rate may be cancelled by a delay in child bearing. Many women in developed countries choose to bear children by their early 30's because the obstacles to successful pregnancy grow as they age. As the last few decades have already shown, extending the fertile period of women's lives would allow them to put off having children until later, until they have developed their careers. Not only will couples have children later, we can expect them to be better positioned financially and psychologically to care for them.
Almost certainly, the first truly effective technologies to extend the maximum human life span will come with a significant cost of human development and application. As a consequence population effects would first be felt in the developed countries. This points to another flaw in the suggestion that extended longevity will dramatically boost population growth. The fact is, superlongevity in the developed nations would have practically no global or local population impact. The lack of global impact is a consequence of the small and falling share of the global population accounted for by the developed nations. No local population boom drama can realistically be expected because these countries are experiencing very low, zero, or negative population growth:
The share of the global population accounted for by the developed nations has fallen from 32 percent in 1950 to 20 percent currently and is projected to fall to 13 percent in 2050.  If we look just at Europe, we see an even more remarkable shrinkage: In 1950, Europe accounted for 22 percent of the global population. Currently it has fallen to 13 percent, and is projected to fall to 7 percent by 2050.  To put this in perspective, consider that the population of Africa at 749 million is now greater than that of Europe at 729 million, according to UN figures. Europe's population growth rate of just 0.03 per cent will ensure that it will rapidly shrink relative to Africa and other developing areas.
In Eastern Europe, population is now shrinking at a rate of 0.2 percent. Between now and 2050, the population of the more developed regions is expected to change little. Projections show that by mid-century, the populations of 39 countries will be smaller than today. Some examples: Japan and Germany 14 percent smaller; Italy and Hungary 25 percent smaller; and the Russian Federation, Georgia and Ukraine between 28-40 percent smaller. 
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 who "did some basic calculations to demonstrate what would happen if we achieved immortality today". 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. 
Low fertility means that population trends in the developed regions of the world would look even milder if not for immigra-tion. As the 2000 Revision to the UN Population Division's projections says: "The more developed regions are expected to continue being net receivers of international migrants, with an average gain of about 2 million per year over the next 50 years. Without migration, the population of more developed regions as a whole would start declining in 2003 rather than in 2025, and by 2050 it would be 126 million less than the 1.18 billion projected under the assumption of continued migration."
All things considered, countries fortunate enough to develop and make available radical solutions to aging and death need not worry about becoming overpopulated. In an ideal scenario, life extension treatments would rapidly plunge in cost, making them affordable well beyond the richest nations. We should therefore look beyond the developed nations and examine global popula-tion trends in case a significantly different picture emerges.
GLOBAL POPULATION FLATLINING
We have seen that we have no reason to hesitate in prolonging life even if population were to grow faster due to higher fertility rates. But does the developing world, with or without cheap, ubiquitous life extension, have much to fear from a population explosion? Are populations growing out of control in those regions? The fad for popular books foretelling doom started in the 1960's, at the tail end of the most rapid increase in population in human history. Since then, the poorer countries, well below us in the development cycle, have also been experiencing a drastic reduction of population growth. This is true despite major relative life extension - the extra decades of life bestowed by medical intervention and nutrition.
Taking a global perspective, the numbers reveal that the average annual population growth rate peaked in 1965-1970 at 2.07 percent. Ever since then, the rate of increase has been declining, coming down to 1.2 per cent annually. That means the addition of 77 million people per year, based on an estimated world population of 6.1 billion in mid-2000.  A mere six countries account for fully half of this growth: India for 21 percent; China for 12 percent; Pakistan for 5 percent; Nigeria for 4 percent; Bangladesh for 4 percent, and Indonesia for 3 percent. China has markedly reduced the average number of births per woman over the last 50 years from six to 1.8. Starting from the same birth rate at that time, India has fallen much less, although still almost halving the rate to 3.23 percent. If these trends continue up to 2050, India's population will exceed that of China. 
Despite the fecundity of these top people-producers, the overall picture is an encouraging one:
The total fertility rate for the world as a whole dropped by nearly two-fifths between 1950/55 and 1990/95 - from about 5 children per woman down to about 3.1 children per woman. Average fertility in the more developed regions fell from 2.8 to 1.7 children per woman, well below biological replacement. Meanwhile total fertility rates in less developed nations fell by 40 percent, falling from 6.2 to 3.5 children per woman. 
We can expect population growth to continue slowing until it reaches a stable size. What size will that be? No one knows for sure, but the best UN numbers indicate that population may peak at as low as 8 billion people, with a medium projection of 9.3 billion and an upper limit projection of 10.9 billion. [2;7] The medium projection also points to global population peaking around 2040 and then starting to fall.
I wrote the first version of this paper in 1996. In revising it, I found it interesting that, less than a decade ago, the higher projection allowed for 12 billion or more. Demographers had continued their long tradition of over-estimating population growth. This effect seems to have been reduced, but take all projections (especially those longer than a generation) with a healthy dose of skepticism.
FORCES OF POPULATION DECELERATION
Why, though, should we expect people in less developed countries, even given contraceptives, to continue choosing to have smaller families? This expectation is not merely speculation based on recent trends. Sound economic reasoning explains the continuing trend, and makes sense of why the poorer nations are only just beginning to make the transition to fewer births.
Decelerating population growth appears to be an inevitable result of growing wealth. Early on in a country's developmental curve, children can be regarded as 'producer goods' (as economists would say). Parents put their children to work on the farm to generate food and revenue. Very little effort is put into caring for the child: no expensive health plans, special classes, trips to Disneyland, X-Men action figures, or mounting phone bills. As we become wealthier, children become 'consumer goods'. That is, we look on them more and more as little people to be enjoyed and pampered and educated, not beasts of burden to help keep the family alive. We spend thousands of dollars on children to keep them healthy, entertain them, and educate them. We come to prefer fewer children to a vast mob of little ones. This preference seems to be reinforced by changing tastes resulting from improved education. The revenue vs. expense equation for extra children further shifts toward having fewer offspring as populations become urbanized. Children cost more to raise in cities and can produce less income than in the country.
Fertility declines for another reason: As poorer countries become wealthier, child mortality falls as a result of improved nutrition, sanitation, and health care. Reduced child mortality in modern times can come about even without a rise in income. People in poorer countries are not stupid; they adjust their childbearing plans to reflect changing conditions. When child death rates are high, research has shown that families have more children to ensure achieving a given family size. They have more children to make up for deaths, and often have additional children in anticipation of later deaths. Families reduce fertility as they realize that fewer births are needed to reach a desired family size. Given the incentives to have fewer children as wealth grows and urbanization proceeds, reduced mortality leads to families choosing to reduce family size.
Economic policy helps shape childbearing incentives. Many of the same people who have decried population growth have supported policies guaranteed to boost childbirths. More than that, they boost childbearing among those least able to raise and educate children well. If we want to encourage people to have more children, we should make it cheaper for them to do so. If we want to discourage fertility, or at least refrain from pushing it up, we should stop subsidizing it. Subsidies include free education (free to the parents, not to the tax-payers), free child health care, and additional welfare payments to women for each child they bear. If parents must personally bear the costs of having children, rather than everyone else paying, people will tend to have just the number of children for whom they can assume financial responsibility.
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. Couples will be able to have children by choice, not by accident. Women should also be encouraged to join the modern world by gaining the ability to pursue vocations other than child-raising.
'OVERPOPULATION' DISTRACTS FROM REAL PROBLEMS
Major downward revisions in population growth - throughout the UN's sixteen rounds of global demographic estimates and projections since 1950 - have drained the plausibility of any overpopulation-based argument against life extension. We can better understand the real problems that are talked about in relation to overpopulation instead as issues of poverty. Poverty, in turn, results not from having too many people, but from several major factors including political misrule, continual warfare, and insecurity of property rights.
As Bjorn Lomborg points out, we find many of the most densely populated countries in Europe. The region with the highest population density, Southeast Asia, has about same number of people per square mile as the United Kingdom. Although India has a large, growing population, it also has a population density far lower than that of The Netherlands, Belgium, or Japan. Lomborg also notes that Ohio and Denmark are more densely populated than Indonesia. 
We should also recognize that most population growth takes place in urban areas, which provide a better standard of living. As a result, most of this planet's landmass will not be more densely populated than it is today. Over the next three decades, we can expect to see almost no change in the rural population of the world and, by 2025, 97% of Europe will be less densely populated than today.  We should celebrate the urbanization trend since even the urban poor thrive better than they would in the country. The causes of this include better water supplies, sewage systems, health services, education, and nutrition.  Oddly enough, serious infectious diseases like malaria are less threatening the closer buildings are together (and so the smaller the space for swampy areas beloved of mosquitoes and flies). 
SUSTAINABILITY AND THE GREAT RESTORATION
The future could be far brighter than the eco-doomsters have long portrayed it. As Ronald Bailey  reports:
Jesse Ausubel, director of the Program for the Human Envi-ronment at Rockefeller University, believes the 21st century will see the beginning of a 'Great Restoration' as humanity's productive activities increasingly withdraw from the natural world.
If world farmers come to match the typical yield of today's US corn growers, ten billion people could eat amply while requiring only half of today's cropland. This is one way in which technological advance in farming will allow vast expanses of land to revert to nature. Transgenic crops could also multiply today's production levels while solving several significant environmental challenges. 
Visions that emphasize human ingenuity and opportunity have a far more impressive historical record than those that emphasize human passivity and helplessness. Paul Ehrlich is a classic case of the latter type and you have only to browse his dark, alarming books to recognize how consistently bad he has been at making environmental predictions. In a 1969 article, Ehrlich predicted the oceans dead from DDT poisoning by 1979 and devoid of fish; 200,000 deaths from 'smog disasters' in New York and Los Angeles in 1973; U.S. life expectancy dropping to 42 years by 1980 because of pesticide-induced cancers, and U.S. population declining to 22.6 million by 1999.  Ehrlich famously lost a ten year bet against cornucopian economist Julian Simon (and refused to renew the bet). In 1974, Ehrlich recommended stockpiling cans of tuna due to the certainty of protein shortages in the USA. And so on.
As Bailey explains , contrary to Ehrlich:
Instead, according to the United Nations, agricultural produc-tion in the developing world has increased by 52 percent per person since 1961. The daily food intake in poor countries has increased from 1,932 calories, barely enough for survival, in 1961 to 2,650 calories in 1998, and is expected to rise to 3,020 by 2030. Likewise, the proportion of people in developing countries who are starving has dropped from 45 percent in 1949 to 18 percent today, and is expected to decline even further to 12 percent in 2010 and just 6 percent in 2030. Food, in other words, is becoming not scarcer but ever more abundant. This is reflected in its price. Since 1800 food prices have decreased by more than 90 percent, and in 2000, according to the World Bank, prices were "lower than ever before".
A reading of economic and social history quickly makes one thing plain: throughout history people have envisaged overpopulation. Even the great nineteenth century social scientist W. Stanley Jevons in 1865 claimed that England's industrial expansion would soon cease due to the exhaustion of the country's coal supply.  However, as shortages developed, prices rose. The profit motive stimulated entrepreneurs to find new sources, to develop better technology for finding and extracting coal, and to transport it to where it was needed. The crisis never happened. Today, the USA has proven reserves sufficient to last hundreds or thousands of years.  If one resource does begin to run low, rising prices will encourage a switch to alternatives. Even a vastly bloated population cannot hope to exhaust energy supplies. (Solar energy and power from nuclear fission and soon fusion are practically endless.) So long as we have plentiful energy we can produce substitute resources and even generate more of existing resources, including food. Even if population were to grow far outside today's highest projections, we can expect human intelligence and technology to comfortably handle the numbers.
Human intelligence, new technology, and a market economy will allow this planet to support many times the current population of 6.2 billion - it can support many more humans than we are likely to see, given trends toward lower birth rates. Many countries, including the USA, have a rather low population density. If the USA's population were as dense as Japan - hardly a crowded place overall - our population would be 3.5 billion rather than 265 million. If the USA had a population density equal to that of Singapore, we would find almost 35 billion people here, or almost seven times the current world population. New technolo-gies, from simple improvements in irrigation and management to current breakthroughs in genetic engineering should continue to improve world food output. Fewer people are starving despite higher populations. This does not mean they are feeling satisfied. Millions still go hungry or are vulnerable to disruptions in supply. We need to push to remove trade barriers, abolish price controls on agriculture (which discourage production and investment), and pressure governments engaging in warfare and collectivization to change their ways.
Nor should we expect pollution to worsen as population grows. Contrary to popular belief, overall pollution in the more developed countries has been decreasing for decades. In the USA, levels of lead have dropped dramatically. Since the 1960's levels of sulfur dioxide, carbon monoxide, ozone, and organic compounds have fallen despite a growing population. Air quality in major urban areas continues to improve, and the Great Lakes are returning toward earlier levels of purity.  This is no accident. As we become wealthier, we have more money to spare for a cleaner environment. When you are longing for food, shelter, and other basics, you will not spare much thought for the environment. So long as mechanisms exist for converting desires for cleaner air and water and space for recreation into the things themselves, we can expect it to happen.
Most effective at spurring the positive changes are markets - price signals creating incentives for moves in the right direction. If polluters must pay for what they produce because their activity intrudes on the property rights of others, they will search for ways to make things with less pollution. Pollution problems do exist. Most of them can be traced to a failure to enforce private property rights, so that resources are treated as free goods that need not be well managed. Fishing in unowned bodies of water is an example of this. The desertification of collectively or government owned land in Africa is another. We can be reasonably confident that the trend towards less pollution with greater population will continue. However, complacency is out of place. We should press for responsible management of resources by privatizing collectively owned resources to create incentives for sound management and renewal.
So long as we continue to allow freedom to generate more wealth and better technology, we can expect pollution to continue abating. More efficient recycling, production processes that generate fewer pollutants, and better monitoring and detection of polluters, along with economic incentives making each producer responsible for their output, will allow us to continue improving our environment even as population grows. Assuming that we achieve complete control of matter at the molecular level, as expected by nanotechnologists, we will have the keys to production without pollution. Another product of molecular manufacturing will be the disappearance of most large-scale, clumsy machinery. Less and less land will need to be used for manufacturing equipment, making more room for people to enjoy. Some manufacturing will be moved into space. The result of these and other changes (some of which are already underway) will be the freeing of the Earth from unwanted, but previously necessary, means and by-products of manufacturing.
The population issue raises numerous factual, economic, and ethical concerns. I urge the interested reader to check into the sources listed in the References, especially the essays by Jesse Ausubel  and the books by Bailey, Lomborg, and Simon. [3;19;20-25] I have only sketched lines of thinking showing that we would be severely misguided not to push for extended life out of fear of overpopulation. Let us move full speed ahead with extending life span: Once we have vanquished aging, I would expect other threats to life, such as war and violent crime, will become even less acceptable. We can look forward to a long-lived society better off than previous generations; not only in economic well being, but also in security of life and health.
1) Ehrlich, Paul R; The Population Bomb (1968); Sierra Club-Ballantine
2) World Population Prospects: The 2000 Revision (2001a); United Nations Publications
3) Lomborg, Bjorn; The Skeptical Environmentalist: Measuring the Real State of the World (2001); Cambridge University Press
4) Olshansky, SJ; "Duration of Life: Is There a Biological Warranty Period?" in: The President's Council on Bioethics (2002) Washington, DC http://www.bioethics.gov/transcripts/dec02/session2.html
5) World Population Prospects: The 2000 Revision, Additional Data (2001c); United Nations Publications
6) Eberstadt, Nicholas; "Population, Food, and Income: Global Trends in the Twentieth Century" in: Bailey (1995).
7) World Population Prospects: The 2000 Revision, Annex Tables (2001b); United Nations Publications
8) World Urbanization Prospects: The 1996 Revision (1998); United Nations Publications
9) The Progress of Nations (1997) UNICEF http://www.unicef.org/pon97/
10) Miller, Jr. Tyler G; Living in the Environment: Principles, Connections, and Solutions (1998); Wadsworth Publishing Company
11) Bailey, Ronald; "The End Is Nigh, Again" in: Reason (2002); June 26
12) Rauch, Jonathan; "Will Frankenfood Save the Planet?" in: The Atlantic Monthly (2003); October
13) Bailey, Ronald; Eco-Scam (1993); St. Martin's Press
15) Jevons S; The Coal Question: An inquiry concerning the progress of the nation and the probable exhaustion of our coal mines (1865); Kelley Publishers
17) Taylor, B et al. "Water Quality and the Great Lakes" in: Michigan's Opportunities and Challenges: Msu Faculty Perspectives, Michigan in Brief: 2002-03. Public Sector Consultants, Inc.
18) Ausubel, Jesse; "The Great Restoration of Nature: Why and How" in: Challenges of a Changing Earth (2002); pg.175-182 // Proceedings of the Global Change Open Science Conference, Amsterdam, Netherlands (2001, 10-13 July) edited by Steffen, W & Jaeger, J & Carson, DJ & Bradshaw C; Springer http://phe.rockefeller.edu/sthubert/hubert.pdf // Ausubel, Jesse; "Where is Energy Going?" in: The Industrial Physicist (2000); http://phe.rockefeller.edu/IndustrialPhysicistWhere/where.pdf
19) The True State of the Planet (1995); edited by Bailey, Ronald; The Free Press
20) Simon, Julian L; "Resources, Population, Environment: An Over-Supply of False Bad News" in: Science (1980, Vol. 280); pg.1431-1437
21) Simon, Julian L; The Ultimate Resource (1981); Princeton University Press
22) Simon, Julian L; "Forecasting the Long-Term Trend of Raw Material Availability," in: International Journal of Forecasting (1985, Vol. 1); pg.85-109.
23) Simon, Julian L; Population Matters (1990); N.J.: Transaction
24) Simon, Julian L; "Bunkrapt: The Abstractions that lead to scares about resources and population growth," in: Extropy (1993, Vol. 11); Summer/Fall 1993, pg.34-41.
25) The Resourceful Earth (1984); edited by Simon, Julian L & Kahn, Herman; Basil Blackwell, Inc.