II. The Duty to Aid: An Operational Level Analysis

Peter Singer's “Famine, Affluence, and Morality” helped bring applied ethics to the fore of moral philosophy by applying the duty to aid to the problem of global poverty. Singer's paper and argument is important to the project in this paper for at least two reasons. First, like Singer, I believe that our moral conceptual scheme needs to be altered, and with it, the way of life that has come to be taken for granted in our society. Singer aspired to raise awareness about the plight of those living in poverty, and to provide a coherent and compelling moral argument as to why those living in affluent countries should do more to aid the poor living in distant lands. In this paper, I aspire to raise awareness about the challenges of global aging (for instance, the rapid rise in the prevalence of chronic disease and disability), and to provide a coherent and compelling argument as to why those living in affluent countries should support the basic scientific research which might help us decelerate the rate of molecular and cellular decline.

Second, like Singer's moral analysis, my argument will invoke a duty to aid those in need. The duty to aid involves undertaking individual and collective actions that I will refer to, following terminology employed by Olshansky, Carnes, and Grahn,Footnote ⁸ as “manufacturing survival time.” Saving drowning children, providing sanitation, antibiotics, seatbelts, and providing food to the hungry are all actions that manufacture survival time. There are two general strategies for manufacturing the survival time of an individual: (1) reclaiming survival time by reducing avoidable mortality (e.g., death from starvation, malaria, appendicitis, infection, accident, violence, cancer, heart disease, stroke, and so forth), and (2) reclaiming survival time by extending the biological warranty period. Footnote ⁹ The former focuses on reducing the proximate causes of suffering, disease and death. The latter adopts the lens of evolutionary biology, and as such expands the duty to aid to include tackling the ultimate causes of suffering, morbidity and mortality. And the reasons for doing so are simple: disease, suffering and death are bad, and we should try to prevent such bad things from occurring to people at all stages (the pre-reproductive, reproductive and post-reproductive) of life. Extending the biological warranty period requires modifying the rate of biological aging (or senescence), so that there is a deceleration of the rate of molecular and cellular decline. This results in extending the healthspan (and lifespan) rather than simply increasing “life expectancy” by reducing mortality risks.

The strategy Singer employs to bring attention to the importance of tackling global poverty is to invoke the following moral principle, which I will refer to as the Duty to Aid:

Singer's moral principle is deficient because it only tracks two (of many) relevant variables—namely, (1) the magnitude of the harm that could be averted, and (2) the cost of intervening (and it is debatable whether Singer's proviso “without thereby sacrificing anything of comparable moral importance” is an adequate account of these costs, but I will put that issue aside here). There are, however, at least four other variables that are likely to arise at the operational level of trying to prevent bad in the real world. These are:

1. (3) the probability that significant harm will occur if one does not intervene.

2. (4) the probability that intervening to aid will be successful in preventing or redressing the bad or harm in question.

3. (5) the magnitude of the benefits of preventing the harm in question.

The sixth variable is one which the duty to aid should actually be insensitive to, rather than track. And this variable is the cause of harm or badness, which is, in itself, irrelevant with respect to the stringency of the duty to aid those who suffer, or are at risk of, serious harm.Footnote ¹¹ This sixth condition (which I shall focus on in Section V) can be stated as such:

1. (6) The fact that the cause of something bad stems from extrinsic factors, intrinsic factors, or a combination of extrinsic and intrinsic factors is not, in itself, relevant to the stringency of the duty to aid those at risk of suffering, disease, or premature death.

Singer's moral principle must be analyzed and refined further, so that many ambiguities concerning how it is employed at the operational level can be rectified. These ambiguities stem from the fact that the applied examples Singer invokes, such as saving a drowning child, and the provision of food and shelter to the poor, are examples that involve protecting humans from certain harms that arise from extrinsic factors which can be prevented or mitigated with certainty (and without regard for the magnitude of the benefits of intervention).

In the real world there are pervasive forms of suffering, disease, and premature death, the risks of which can range from possible to certain. And the likelihood that interventions can successfully prevent such harms can also vary from low likelihood of success to certainty of success. And finally, the magnitude of the benefits of possible intervention can range from short-term (prevent suffering and death for a few weeks or months) to long-term benefits (prevent suffering and death for the foreseeable future). The duty to aid must track these kinds of variables that arise at the operational level.

III. Probable Harms, Prospects for Success, and the Magnitude of Benefits

In Singer's original example he asks us to imagine a scenario in which we witness a child drowning in a pond. While the example is simple, it is effective because it helps draw attention to the moral sensibilities we have concerning the strength of the imperative to aid others in need and what we feel is the appropriate burden others should be willing to shoulder to aid those in need. The first revision of Singer's drowning example that I would like to make modifies the certainty of the child drowning to a probability of the child drowning. Suppose the pond in question has a lifeguard on duty to rescue people. You see the child drowning and also notice an able lifeguard swimming quickly to aid the child. What do you do? If the pond is very shallow, and the water very calm, it is reasonable to assume that the lifeguard will successfully rescue the child, and thus the duty to aid (as it applies to you) evaporates in this particular example because the probability of the child suffering serious harm is close to zero.

But we could modify the example in different ways—e.g., making the water more hazardous, the lifeguard inexperienced, and so on—that could increase the odds that the child would drown without your help. The stringency of the duty to aid others ought to track the probability that harm will be realized if you do not intervene. All else being equal (e.g., the severity of harm and cost of intervening), the greater the probability that nonintervention will result in serious harm, the more stringent the duty to aid.

Singer's moral principle, as originally formulated by him, is very constrained because it only applies in the limited cases where there is a 100 percent certainty of harm being realized. But many real-world harms, such as risk of infectious disease, famine, cancer, climate change, etc., are probable or even just possible problems. And the duty to aid should also provide some guidance for action in those cases, otherwise all efforts to aid will be diverted solely to preventing certain harms while ignoring probable, and potentially greater, harms.

As originally formulated, Singer's principle of preventing bad occurrences is an impotent moral principle for guiding moral action in the real world because it assumes that the relevant harms in question (i.e., suffering and death from poverty and lack of medicine) can be prevented with 100 percent certainty and it provides insufficient details concerning the relevant benefits of intervention; that is, it is unclear whether the prevention of suffering and death means extending life by two days, twenty years, indefintely, etc. In the drowning child scenario Singer describes, there is a 100 percent certainty that intervention will result in success (i.e., saving the child from drowning). Furthermore, because it is a child drowning, it is also the case that “preventing the child from drowning” will likely result in “adding 60–70 years of additional life.” And these two factors thus make the intuitive force of the duty to aid the drowning child very stringent.

However, when Singer moves to the example of helping the poor in distant lands, he insists that the probability of preventing suffering and death from lack of food, shelter, and medicine is also a certainty with little regard for the magnitude of the benefits of intervention (beyond saying “it prevents suffering and death”). Here is a very telling passage that illustrates this first point:

In the forty years since Singer wrote that statement it has become clear that the story of humanitarian aid is, at best, a mixed story of both failures and successes. Effectively combating global poverty has proved to be much more challenging and complex than Singer presupposed in 1972.Footnote ¹³ The expert observers and famine relief organizations did not always pursue policies that helped (in the short- or long term) the poor. Indeed, sometimes these interventions made the situation even worse, despite good intentions. Once we attend to the probability that intervention can successfully prevent bad in the real world, a further guideline informs the duty to aid: all else being equal, the greater the chances are that we can prevent serious harm, the more stringent the duty to aid.

In addition to ignoring the probability that intervention will be successful, Singer's principle and examples obscure the details of the specific benefits of intervention. By characterizing the goal of aiding as a general duty to “prevent suffering and premature death” it is not clear if we are obligated to prevent harm only for the short term, the long term, or permanently. One can plausibly presume that Singer means permanently preventing (i.e., eliminating) the suffering and death caused by lack of food, shelter, and medicine. But then his claim that it is just as easy to help a refugee in Bengal as it is to help a poor neighbor down the street is clearly erroneous.

Assuming the neighbor down the street lives in a society that already has access to clean drinking water, security (e.g., effective police force), a strong economy, and so forth, the odds that providing some food to him will, in the long run, prevent him from suffering and dying from poverty is much higher than the odds facing the person who lives in a less developed country that is plagued by infectious disease, lacks basic sanitation, is prone to civil war and conflict, and so on. Providing the globally poor with food and supplies for one month is not, itself, likely to redress the problems of global poverty.

Singer deliberately limits his principle to refer only to the “prevention of something bad,” rather than suggest the duty requires us to benefit others. Footnote ¹⁴ He wants to avoid suggesting that others are morally required to benefit people, as that would lead to a principle to maximize utility that would enslave everyone to work for the greatest happiness of the greatest number. Singer's principle only instructs us to prevent avoidable suffering and death. And in a world devoid of such harms people are morally free to do as they wish. But by failing to provide more details about the benefits of intervention, Singer's principle becomes untenable, for very few harms can be permanently eliminated. And this means that attention ought to be placed on the different kinds of benefits that preventing harm can confer. All else being equal, the greater the benefits of preventing something bad from happening, the greater the duty to prevent the bad in question.

Bringing the various points together, we can now state our modified duty to aid (Modified DA) as follows:

This modified principle, unlike Singer's original formulation, can serve as a useful moral compass for guiding action to address the dilemmas that arise in a world with limited resources and pervasive suffering, disease, and premature death. With this contextualized account of the duty to aid in hand, we can now begin to make the case for aspiring to extend the human biological warranty period.

IV. Saving Drowning Children and Drowning Grandparents

Return again to Singer's example of the drowning child. Instead of the young child drowning in a pond, let us now imagine that it is sixty years into the future from Singer's imagined drowning example. The child is now a sixty-five-year-old adult, in fact she is a grandmother, and has returned to the very same pond where she almost drowned sixty years earlier. She has brought her grandson with her, to enjoy a picnic lunch and explore the pond. While chasing tadpoles with her grandson in the pond, the grandmother slips on a rock and hits her head. She now lays unconscious at the bottom of the shallow pond that nearly took her life sixty years earlier. You are walking by the pond and hear the grandson's pleas for someone to help his grandmother (he is not strong enough to rescue her). What do you do?

I shall assume that most readers share my conviction that we should aid the drowning grandmother. Furthermore, I believe the stringency of the duty to aid in this example is very pressing, and of equal strength to the imperative to help her when she was a child. The urgency to prevent suffering and death does not dissipate, or even severely diminish, simply because the grandmother is now older than she was sixty years earlier. She still deserves to be treated as a moral equal to other persons; her chronological age does not erode this status as an equal. She, like all of us, has interests, aspirations, and goals that are worthy of respect and consideration. Thus we ought, if it is within our power to prevent something bad from happening without sacrificing something of comparable moral importance, to aid her.

This modified version of Singer's drowning example illustrates the point that the age of the person in need of assistance by itself has no ethical relevance in the drowning example. The person who saves drowning children, but is unmoved to aid drowning grandparents, acts unethically. His or her actions are “ageist.” Robert Butler, the first director of the National Institutes of Health's National Institute on Aging, coined the term “ageism” in 1969,Footnote ¹⁵ which means a systematic stereotyping of, and discrimination against, people because they are old. Ageism violates the humanist conviction that all persons' interests matter, and they matter equally. The age of a person in need, just like the nationality of those in need, has no ethical significance.

However, it is important to note that, at the operational level of implementing DA in practice, the age of those in need of assistance can be relevant as age often functions as a proxy for estimating the “expected utility” (or benefits) of an intervention, and this can be a relevant consideration when the resources available to aid those in need are insufficient to redress all preventable suffering and death in the world.

Recall that modified DA has the stipulation that the greater the benefits of preventing something very bad from happening, all else being equal, the greater the moral duty to prevent the bad in question. But all else is not necessarily equal, and this reality means that the duty to aid cannot be simply partitioned into serially ordered duties, with the duty to save children having lexical priority over the duty to prevent suffering, disease, and death late in life. We must attend to both kinds of harm, and the stringency of the duty to prevent the risks associated with premature death should depend upon the considerations that modified DA stipulates (e.g., the probability that nonintervention will result in harm, the probability that intervention be successful, the cost of intervention, and the magnitude of the benefits of intervention).

In the following sections the duty to aid will be viewed through the lens of biogerontology. This will bring into sharper focus the constraints on the upper limits of human longevity as well as the available, and potential, strategies for preventing disease and death in the pre-reproductive, reproductive, and post-reproductive stages of life. The primary focus is on the latter. In particular, I contrast the benefits likely to be realized by continuing down the path of trying to reclaim potential survival time near the limits of average maximum lifespan (potential lifespan) with the benefits likely to be realized by extending the biological warranty period (extended lifespan).

V. Extrinsic and Intrinsic Causes of Harm

A further limitation of Singer's original moral principle (DA), and his examples of saving drowning children and redressing global poverty, is that the aspiration to manufacture survival time is understood as only entailing a duty to reclaim potential survival time when it ought to also entail a duty to extend lifespan (by extending the biological warranty period). The latter can also prevent suffering and premature death because it retards the rate of molecular and cellular decline. This oversight was perhaps a reasonable one to make when Singer was writing in the early 1970s and our understanding of aging was much more limited. However, given the advances that have been made over the past four decades in the field of biogerontology, the exclusive focus on reclaiming potential survival time is no longer warranted. Viewing the duty to aid through the lens of biogerontology is useful for redressing this operational level deficiency of DA. To set the stage for that discussion (in the following section), we must first recognize the different causes of harms like suffering, disease, and death.

Broadly speaking, there are three different causes of the kinds of harms DA seeks to mitigate. These are extrinsic factors, intrinsic factors, and a combination of extrinsic and intrinsic factors. Extrinsic factors are those typical of the world's hostile environment. For example, infectious diseases like smallpox and malaria, natural disasters (e.g., hurricanes), violence, scarcity of resources, and unjust institutions. But there are also intrinsic factors, such as our biological design, that make our bodies and minds less resistant to various kinds of stress over time. “Intrinsic causes of death are those that remain after the total elimination of extrinsic causes of death.”Footnote ¹⁶

Most instances of disease and death are a combination of both intrinsic and extrinsic factors. Take, for example, poverty. It is easy to assume that all the causes of malnutrition stem from extrinsic factors, like a lack of food or unsound or unjust public policies that cause food shortages. A person that does not have ample food will be malnourished, and thus vulnerable to disease and suffering and, eventually, death. However, this explanation is only part of the story of our vulnerability to starvation. There are also intrinsic factors at play. Not every mammal will die if it goes days, weeks, even months, without food.

Bears, for example, can survive prolonged periods of time without food when they hibernate. What determines the nourishment requirements humans need to stay healthy and alive? Why is it that humans cannot be sustained with less frequent access to food? The biology of Homo sapiens is thus implicated in the story of our vulnerability to starvation in the world. If humans had the ability to slow down their metabolism, as animals that hibernate can, they could reduce the expenditure of energy when food is scarce. But humans do not have this biological capability. We have basic material needs that must be met frequently (i.e., almost daily). And these nutritional demands mean that we risk malnourishment, even starvation, when the supply of food is not steady. The metabolism we have today is a result of our species' evolutionary and life history.Footnote ¹⁷

A complete picture of all the causes of disease and death would include extrinsic and intrinsic factors, as well proximate and ultimate causation. One might wonder why I even bring up the intrinsic, evolutionary factors at play in the story of malnourishment. Am I suggesting we could redesign the human metabolism to combat global poverty? No. But actually considering such a case can be instructive and help explain why it is important to aspire to decelerate the rate of aging.

To illustrate the significance of identifying the different causes of avoidable suffering and disease, when it comes to the operational level of DA, consider the following purely hypothetical and fanciful scenario. Suppose that, while Singer was writing in 1972, a new drug had just been developed that safely and effectively reprogrammed the metabolism of the human body. By simply taking one (relatively inexpensive) pill a month, the daily food and drink a person consumed would automatically be converted into the nutrients typical of a healthy, balanced diet regardless of the quantity and quality of provisions consumed. Consuming even just a minimal amount of rice and water could, when taken in conjunction with this metabolic drug, be equivalent to consuming the nourishment provided by eating a balanced diet composed of fruits and vegetables, meat, and bread.

Furthermore, imagine also that the person taking this pill, in conjunction with minimal amounts of food and water, would not feel any hunger pains after taking this pill. So the psychological, as well as physiological, effects of eating a balanced and healthy diet would also be realized. Suppose this scientific discovery occurred on the eve of Singer completing his paper “Famine, Affluence and Morality.” Would he have reason to edit and revise his paper before sending it off for publication? I think he would.

It would be odd to invoke DA and insist that those living in affluent countries donate money only to charities which would ship food halfway across the world to impoverished nations if there was another, more efficient and effective, way to prevent the bad of poverty. DA does not prejudge what constitutes the most effective way to prevent the bad of avoidable suffering and death. It merely instructs us to prevent something bad from happening when we can prevent this bad, without sacrificing something of comparable moral significance. Assuming the drug in question was truly safe and effective, the provision and distribution of such a pill could be a more effective way of combating the harms of poverty than trying to redress all the extrinsic factors at play with food provision (e.g., drought, floods, war, agricultural infrastructure, and so forth). Such a pill would be viewed as “a medicine” which protects against malnourishment. And if we could prevent suffering and death by providing this medicine to the world's poor then we ought to do so.

When it comes to malnourishment we perhaps naturally think the provision of food is the central strategy for combating poverty because it redresses one extrinsic factor (namely, the shortage of food). But eliminating poverty is vastly more complex and challenging than simply “making food available.” Forty years after the publication of Singer's article millions of people still live in poverty, despite enormous humanitarian efforts to eradicate poverty. Could we do more? Yes. But poverty persists not only because of a lack of “political will,” but also because of a lack of knowledge concerning the most effective ways of mitigating poverty in the long term in diverse regions of the world. Our knowledge has improved since 1972, but there is still much work that needs to be done in order to improve the likelihood that intervention will successfully redress the root causes of poverty.

Singer's appeal to DA in the context of global poverty is effective because the link between “lack of food” and “harm or badness” is self-evident. One does not need to invest a great deal of attention or insight to the relevant context to know that not having enough nourishment will result in something bad. So for many extrinsic risk factors, the imperative to aid will have intuitive traction. And for such cases an appeal to a general principle like DA could be useful in motivating individuals and governments to act to prevent harm (which was Singer's central goal). Unfortunately this is not the case for many intrinsic factors, especially those caused over the long period of our evolutionary and life history. Many people will conceive of these risk factors as simply “natural” and/or “inevitable,” when in fact they are, in an important sense, unnatural and, most importantly, they are malleable (even though they are, ultimately, inevitable).

A contextual empirical analysis can thus be of great service if it can bring to the fore a more comprehensive understanding of the health risks facing aging populations. And this is why the story of the intrinsic factors that influence the health prospects for humans in the post-reproductive stage of life is important.

VI. Essential versus Potential Lifespan

The duty to aid must take seriously the biological determinates of, and constraints upon, longevity given the reality that all deaths can be classified as “premature.” “Living a perfect life in a perpetually perfect environment and avoiding all avoidable mortality risks is impossible.”Footnote ¹⁸ In this section, I detail the difference between “essential lifespan” and “potential lifespan.” The former determines the biological warranty period of humans and the latter is the focus of interventions that seek to reclaim our survival time by preventing specific mortality risks. Reclaiming survival time can be achieved by interventions which reduce extrinsic risk actors (like infection, poverty, and poor diet) and by interventions “that suppress (but do not cure) mortality risks arising from the intrinsic biology of the organism (e.g., some forms of cancer and heart disease).”Footnote ¹⁹

The “essential lifespan” of a species is defined as “the time required to fulfill the Darwinian purpose of life, that is, successful reproduction and continuation of generations.”Footnote ²⁰ If it takes a particular species, like Homo sapiens, thirteen to fifteen years for offspring to reach sexual maturity, then the mortality risks facing such a species at both the pre-reproductive and reproductive stages of life had to be significantly lower than those that face a short-lived species like mice. Offspring that are dependent upon others (for example, dependent on parents or grandparents) for food and protection for years while they develop can only survive if those caring for them are also able to survive long enough to care for and raise offspring. This is not the case for small mammals like mice. Mice reach sexual maturity in a matter of weeks, not years. This reflects the empirical reality that mice face very high mortality risks from predators. Thus, mice could not afford to take the same route Homo sapiens have taken to win the race against death. A faster rate of development is the winning strategy when the external pressures are so great that it is unlikely any parent could survive for very long in such a hostile environment.

The essential lifespan of a species thus shapes and determines the “biological warranty period” of that species and of individuals. This is the period of time when intrinsic failures of our biology are not expected. The warranty period itself is not selected for; rather, it is an “inadvertent byproduct of evolutionary neglect, and genetic programs for growth, development and reproduction.”Footnote ²¹

In their extensive cross-cultural examination of longevity in hunter-gatherers, Michael Gurven and Hillard Kaplan conclude that “human bodies are designed to function well for about seven decades in the environment in which our species evolved.”Footnote ²² Within this seven-decade period of time humans could, if they escaped the extrinsic threats to their lives, reach sexual maturity, produce, and nurture their offspring. And, for at least one-fourth of the adult population living in such conditions (for example, with no sanitation, no immunizations or medicine, no predictable food supply, and so on), they likely lived fifteen to twenty years as grandparents.Footnote ²³

This seven-decade estimate for the warranty period also matches up with morbidity rates in aging populations. After this period of time most people will have multiple chronic conditions and mortality rates rise considerably. Multiple chronic conditions are evident in 62 percent of Americans over age sixty-five.Footnote ²⁴ And it is the management of those conditions that permits mortality rates to decline to a level at which life expectancy can reach a number near the upper limits (approximately eighty-five years) of average potential lifespan.

The prolonged survival of a species beyond the expiration of the biological warranty period is thus “unnatural” in the sense that it would not occur without human intervention. In 1953, Peter Medawar described senescence as something “revealed and made manifest by the most unnatural experiment of prolonging human life by sheltering it from the hazards of its natural existence.”Footnote ²⁵ “Humans, and the animals we choose to protect, are the only species in which large numbers experience ageing.”Footnote ²⁶ Without the benefits of the knowledge of hygiene and biomedicine, only a small percentage of people would live long enough to experience what occurs when the biological warranty period expires (e.g., survival time procured by managing multimoribidity).

Unlike the essential lifespan of a species, which is the length of time its members must survive to successfully reproduce at the rate sufficiently high to win the race against death, the “potential lifespan” is how long a person or population could live if all avoidable mortality risks could be eliminated. Suppose, for example, it were possible to eliminate all premature deaths caused by the extrinsic factors of poverty, infectious disease, accidents, war, and so forth. Furthermore, assume that all populations in the world had the medical knowledge and resources that the United States possesses today to suppress some of the mortality risks intrinsic to our biology, such as some forms of cancer, heart disease, etc. In such an idealized scenario the life expectancy of humans on the planet would be close to approaching the average potential lifespan of our species, which is estimated to be approximately eight-five years. Such an estimate is based on insights from demography,Footnote ²⁷ as well as comparative biology,Footnote ²⁸ which compares interspecies mortality. Jeffrey Fries explains how estimates of the human lifespan are arrived at:

It is of course impossible to eliminate all extrinsic risks of premature death. There will always be accidents, for example, that result in people dying before they would from intrinsic factors. Nor is it likely that all the intrinsic risks of our biology, like cancer and heart disease, will be eliminated. But this does not prevent us from aspiring to do so. In 1971, President Richard Nixon declared a “War on Cancer” and signed the National Cancer Act. More than forty years later not a single cancer has been eliminated and yet billions is spent each year on cancer research in the United States. The National Institute of Health's estimated investment, for the year 2013, in cancer research is 5.4 billion dollars.Footnote ³⁰ The current approach of the medical sciences in the United States is to aggressively pursue reclaiming potential survival time near the upper limits of longevity by investing billions of dollars annually in the development of drugs and treatments to reduce the risk of death by specific diseases. This approach does not extend the human “healthspan,” as such interventions mostly apply to persons past or near the expiration of the biological warranty period. As such they help people survive for longer by managing multiple maladies. Viewing the duty to aid through the lens of biogerontology can open up an alternative strategy for tackling the health challenges of late life.

VII. The Duty to Aid Viewed through the Lens of Biogerontology

The duty to aid would look very different if our biology were such that the only things that could cause suffering, disease, and premature death were extrinsic factors like infectious disease, poverty, and unhealthy diets. But these extrinsic factors are only part of the story of the cause of badness in the world. To fixate only on the duty to redress extrinsic harms is to subscribe to the mistaken view of what one might call “environmental determinism.” Like “genetic determinism,” which mistakenly assumes that a person's genes determine a host of complex phenotypes (such as personality and health), “environmental determinism” subscribes to the mistaken view that a person's health prospects are determined solely by environmental factors, such as socioeconomic prosperity, access to education, diet and exercise, and so forth. Such a perspective thus ignores the genetic endowments a person is born with and the evolutionary and life history of our species that influences that genetic heritage.

Why do individuals have any intrinsic constraints upon their health and longevity? Why is it the case that we are not designed for permanent maintenance? The disposable soma theory provides the answer.Footnote ³¹ This account of aging maintains that biological aging occurs because natural selection favors a strategy in which reproduction is made a higher biological priority (in terms of the utilization of resources) than the somatic maintenance needed for indefinite survival. The story of the intrinsic constraints of our biology thus begins with the story of the world's extrinsic risks. The world is a dangerous place. Death is, for all living things on this planet, inevitable.Footnote ³² In order for any species' existence to persist over time a solution to death must be found. And that solution, for us and for other sexually reproducing species, is reproduction. There is thus a real race between reproduction and death, and all the species alive today are, at least for the moment, winning this race. But for all the species that are now extinct, like the Mammoth and Neanderthal, the race was lost.

Adopting this organismal perspective is important because it brings to the fore the fact that a biological trade-off must be, and has been, made between the physiological resources we invest into reproduction and those invested in the maintenance of the soma. Reproduction is given a higher biological priority, which means that, while our bodies and minds are not designed to fail, a consequence of their being designed for reproduction is that there are inevitable health problems as the “biological warranty period” expires (typically by the seventh decade of life).

Surviving long enough to experience the co-morbidity of late life is an “unnatural” state of affairs made possible by modern techniques of manufacturing survival time near the limits of the average maximal lifespan. Stents can be inserted into coronary arteries to help treat coronary heart disease. Diuretics can help manage hypertension. Chemotherapy can kill fast growing cells in the human body. Artificial hips, knees, and shoulder joints can restore some of the range of motion and mobility compromised by the wear and tear of life on our bones and joints.

We have not, at least yet, cured any chronic disease of late life. But by spending enormous sums of money developing drugs and interventions to reclaim potential survival time in late life (by reducing avoidable mortality, like cancer), the developed world has been able to permit individuals to survive beyond the expiration of their biological warranty periods. This is done by funding the expensive project of managing multiple morbidities. Such an approach to health extension is unlikely to be sustainable, either for developingFootnote ³³ or developed countries, as populations continue to age this century.

As the number of people over the age of sixty-five increases, especially those above age eighty, the current approach of tackling specific diseases of aging becomes more and more strained. The costs associated with care for those managing multiple diseases increases, and the health dividend yielded by reclaiming survival time near the upper limits of average lifespan diminishes the closer that limit is reached. This is so because of co-morbidity, which means that staving off one disease, like one type of cancer, does nothing to impact the risks of developing another type of cancer, stroke, Alzheimer's disease, heart disease, and so forth.

Some, admittedly rare, individuals naturally possess the “longevity genes” required for an extended biological warranty period. And these individuals are centenarians (age ≥ 100) and supercentenarians (age ≥ 110). In the United States and other industrialized nations, centenarians occur at a prevalence rate of about one per six thousand. And supercentenarians occur at a rate of about one per seven million.Footnote ³⁴ Centenarians markedly delay or even escape age-associated diseases.Footnote ³⁵ The development of a novel medical intervention that would permit us to replicate the biology of those who age in this exceptionally healthy way would be among this century's greatest medical breakthroughs. Extending the biological warranty period offers the promise of adding years of healthy life to older ages.

Extending lifespan, in contrast to reclaiming potential survival time, involves developing interventions that delay the onset of disease and disability by directly modifying our biology. This might sound like a completely implausible prospect, but scientists have extended the biological warranty period in a variety of species, including worms, mice, and monkeys via caloric restriction (CR) and genetic intervention. These interventions demonstrate that novel interventions can, in principle, extend the biological warranty period. At this stage there is still uncertainty about the impact similar interventions would have on human health and longevity.

Some have estimated that, if the effects of the magnitude of the benefits of CR on mice were replicated in humans, this would mean it would take individuals 112 years to have the abilities and risks of today's seventy-eight-year-old adult.Footnote ³⁶ This would mean extending the biological warranty period of the average person from seven decades to over ten decades. This is very different from merely keeping someone alive for three more decades by helping her manage multiple diseases and disorders. The approach of “reclaiming” potential survival time near the upper limits of average lifespan runs the risk of extending the period of frailty at the end of life. That is the downside of applying the duty to aid to mitigate every proximate cause of disease and death. Extending the biological warranty period offers a very different outcome in terms of the quality of life persons could enjoy in the post-reproductive stage of life.

In contrast to the scenario of “adding more years to life,” tackling aging itself promises to “add life to years.” An intervention that extends the biological warranty period would extend the healthspan, thus delaying the onset of the disease, frailty and disability of late life. And even if the magnitude of the benefits of such an intervention were a small fraction of those realized in CR experiments with mice, slowing aging by just seven years is estimated to reduce the age-specific risk of death, frailty, and disability by approximately half at every age.Footnote ³⁷ This is why, when Modified DA is applied to the dilemmas posed by global aging, it is important to distinguish between the benefits of reclaiming survival time near the upper limits of average maximum lifespan and those expected from extending the lifespan via extending the biological warranty period. Benefits matter. And, all else being equal, it is more important to add more life to years than years to life. A consequence of extending the biological warranty period is that people would live longer lives. But the purpose of extending the warranty period is to prevent disease, suffering, frailty, and disability (as prescribed by the principle of preventing bad occurrences).

Would extending the biological warranty period compress morbidity at the end of life? There is reason to think this could be an additional benefit of retarding aging. It has been observed that supercentenariansFootnote ³⁸ and centenariansFootnote ³⁹ have a compression of morbidity at the end of life. Exceptionally long-lived individuals perhaps hold the key to the goal of delaying disease and frailty, as well as compressing the period of time persons must experience these maladies at the end of life. The exceptionally long-lived share “longevity genes”Footnote ⁴⁰ that extend the biological warranty period.

The health prospects of the exceptionally long lived (age > 100) should be the baseline the duty to aid adopts for determining what constitutes “premature death” in today's aging world. This would permit the duty to better track both intrinsic and extrinsic factors that cause disease, suffering and disability and thus expand the potential strategies to be explored for increasing the opportunities for health.

VIII. Two Objections

The operational-level considerations Modified DA emphasizes makes, I have argued, a strong case in favor of adding age retardation to the list of strategies to pursue in order to manufacture survival time. Recall that Modified DA draws attention to the probability that nonintervention will result in something very bad, the likelihood that these harms can be prevented, and the magnitude of the benefits of intervening. The harms of aging are certain; nonintervention in the aging process will result in much more suffering, disease, and disability in the world than there need be. Furthermore, given what science has unravelled about aging, especially “exceptionally healthy aging,” there is now a sound empirical basis for believing that intervening in the aging process could extend the biological warranty period of humans. And the magnitude of the benefits of doing so, given the number of persons projected to be over age sixty by the middle of this century, helps solidify the case for taking urgent and committed action to retard the rate of biological aging.

Many objections are often raised against life extension, and thus by extension, to the suggestion that we are obligated to extend the human biological warranty period. I will briefly address two standard objections that one commonly encounters. These concerns are the potential harms of overpopulationFootnote ⁴¹ and a worry that new technologies that intervene directly in our biology to extend life will only serve to further exacerbate the health inequalities that exist between the developed and developing world. I shall call the first objection the Too Many People in the World is Bad Objection, and the second objection the Greater Inequality is Bad Objection.

While I think both objections express potential concerns Footnote ⁴² about extending healthspan, I am sceptical that these concerns would support the conclusion that the health and economic benefits of age retardation should, all things considered, be forfeited for the benefit of population reduction and/or less health inequality.

With respect to global population, perhaps the natural question to ask is how many people are too many for this planet? But this general question might not be the most useful one to ask. The world is a diverse place. The size of the population living in different countries varies, as do fertility rates and the amount of land and resources available to the people living in different geographical territories. The situation of Canada, for example, a country with a relatively small population considering its size and low fertility rate, is very different from a country that is more densely populated and has a higher fertility rate, like Bangladesh.

The population of many developed countries will actually decline over this century, and these countries see increasing the number of healthy, productive workers contributing to their economies as a vital necessity. That is why most countries pursue immigration. Keeping people healthy and productive would confer significant individual and societal benefits, and these benefits must be considered when weighing up the pros and cons of age retardation.

The life prospects of people living in disparate parts of the world are interconnected in different and complex ways. No continent or country is an island. Population growth in one region of the world can strain resources elsewhere, and increase problems like pollution and climate change. And yet it seems odd, if not perverse, to suggest that these problems be addressed by forfeiting health innovations that could reduce the prevalence of chronic diseases like cancer, heart disease, and stroke. Why does the critic of biogerontology select just this one potential health intervention as the one to forfeit? Why not propose forfeiting the benefits of exercise, smoking cessation, sanitation, or antibiotics? Or, taking their logic even further, why not propose increasing the mortality rates from accidents, war, or infectious disease? Such measures could be very effective in constraining global population growth. And they could be more humane and cheaper than the slow, expensive, and painful death by chronic disease.

Proposing to decrease global population by increasing the mortality of war, accidents, or lung cancer no doubt strikes us as grossly unjust and, well, just plain silly. Why? Because the duty to aid entails we prevent wars, accidents, and lung cancer unless the sacrifice involves something of comparable moral importance. Are the overall harmful effects of population growth so severe and large that we should forfeit the health and economic benefits of any health innovation (including an anti-aging intervention)? If they are, then we would need to rethink our attitude on all public health measures and not just an applied gerontological intervention. To object only to modes of manufacturing survival time that extend lifespan is ageist because it assumes the interest people have in remaining healthy during the post-reproductive period of life is not worthy of the same respect and value that we place on those interests in the reproductive and pre-reproductive stages of life.

The burden of proof is thus on the critic of age retardation to demonstrate that a more pressing moral demand (one more specific than a vague reference to “overpopulation”) of the duty to aid trumps the duty to promote the health of the two billion people who will be over age sixty by the middle of this century. This means that something of comparable moral importance to reducing chronic disease for billions of people must be at risk, and this risk must be as certain as the harms of senescence.

The rational response to the problems of population growth is to support the fair and empirically demonstrated measures that have been successful in curtailing population growth. The tried and tested solutions include education (especially of women), access to birth control, economic development, alterations in social attitudes toward the family and gender, and so on. My response to the Too Many People in the World is Bad Objection against retarding aging is the same response I would invoke to defend any other measure that manufactures survival time—curbing fertility, rather than forfeiting health innovations, is likely to be the more fair and viable solution to these problems.

The Greater Inequality is Bad Objection raises different types of concerns, many of which take place against the background of debates about the alleged intrinsic and/or instrumental value of distributive equality. I do not have the space needed to address these larger philosophical points here. But the critic who raises the Greater Inequality is Bad Objection against extending the biological warranty period is most likely worried about the fair diffusion of an anti-aging intervention. If such a technology is (at least initially) quite expensive, they worry, then it is only likely to be enjoyed by people living in the richest countries. And these people already enjoy the longest lives. So this would further exacerbate the injustice of existing health inequalities.

To assess their concerns it is perhaps best to reflect upon our attitudes to other, existing interventions, which manufacture survival time to see what the appropriate response to this potential objection to an aging intervention might be. The benefits of sanitation, for example, are unequally accessible to the global population. And I believe this is unjust. However, saying this does not entail that we have compelling grounds for forfeiting the benefits of the sanitation revolution. It would be perverse to say: “Well, two billion people do not enjoy the benefits of the sanitation revolution, therefore, the other five billion people in the world should not enjoy them either. I would prefer everyone to be equally vulnerable than to permit some to enjoy lower risks of morbidity and mortality.” The reason we do not take such a position is that, even if we take the view that equality has intrinsic and/or instrumental value, the benefits of levelling down with respect to health are not weighty enough to override what we lose in utility from higher rates of morbidity and mortality.

What would be preferable, the egalitarian might argue, is a situation of “levelling up.” Everyone in the world should enjoy the benefits of the sanitation revolution. I agree with this sentiment. But what prevents this from being the case? Concerns about equitable access to health interventions must take seriously the different obstacles that face the fair diffusion of health innovations. The reasons why health innovations are not equally accessible to all are often varied and complex. The obstacles to universalising the benefits of smoke cessation, for example, are different from the obstacles that arise with sanitation, immunizations, chemotherapy, and triple bypass heart surgery.

The intervention I have described in this paper, namely an “anti-aging” pill that mimics the effects of caloric restriction or the “longevity genes” of centenarians, does not require the expertise of surgeons to operate on humans, nor does it require the complex infrastructure required to tap clean drinking into the homes of millions of people living in dense and polluted urban settings. So the obstacles facing the development and diffusion of a pharmaceutical that retards aging is very different from many of the obstacles that face interventions that reclaim potential survival time.

The biggest hurdle facing the development of an intervention that extends the biological warranty period is most likely research and development. Once such a pill is developed, and approved for safety and efficacy, then the dispersion of it should be relatively straightforward. The obstacles to diffusing such a pill would probably be more comparable to those facing the provision of micronutrient supplements (to combat vitamin A and iron deficiencies, for example) or the birth control pill than to sanitation or major surgery. So I believe there is some basis for being optimistic that an aging intervention would be more accessible to the world's poor than the expensive medical interventions that reclaim potential lifespan.

Those committed to promoting the health and economic prospects of the world's poor ought to also be committed to extending the biological warranty period. The poorest aging populations in the world cannot rely on Social Security and the health care that many enjoy in the developed world. Remaining healthy and productive is even more vital for the world's poor. Thus biogerontology could help, rather than hinder, the goal of eliminating global poverty. Countries with a healthy population are much more likely to escape poverty than they are if citizens with a lifetime of experience and knowledge are more vulnerable to disability, disease and death.