Geroscience and Public Health’s Plastic “Ecology of Ideas”

Abstract

In his 1910 JAMA address, the physician and pathologist Christian Herter (1865–1910) emphasized the importance of plasticity in science. Herter’s insight is significant for understanding how public health’s “ecology of ideas” must evolve and change as the health challenges facing populations alter through the different stages of “epidemiologic transition”. The foundational moral aspiration (ie, disease control) and intellectual suppositions (eg, that public health is “purchasable”) of the early twentieth-century public health pioneers C.-E.A Winslow (1877–1957) and his mentor Hermann Biggs (1859–1923) were shaped by sanitation science and were deployed to mitigate the risks of early-life mortality. But to meet the health challenges of today’s aging world, public health’s “ecology of ideas” must be plastic, and thus open to revision and refinement in terms of both its foundational moral aspirations and the intellectual suppositions concerning how to best improve population health. More medical research is needed in rate (of aging) control versus disease control.

In reality, our science is fortunately plastic, constantly subject to revision of its facts, and ever ready to welcome new interpretations of old facts as well as new discoveries, both great and small. This very plasticity it is that makes progress attainable and fascinates our minds. But our textbooks and our lectures are necessarily conservative and dispose us strongly to the notion of fixity of facts, making our minds statical in conception.

Christian Herter (1865–1910), physician and pathologist. JAMA Address, “Imagination and Idealism in the Medical Sciences” (1).

The constraint of limited public funding for biomedical research means that all areas of health-related research must provide compelling rationales not only for why the public should help fund specific areas of scientific research but also for why some areas of research should be a higher priority over other areas of research. Table 1 shows the different public health and medical research priorities in the United States, as reflected in the 2022 National Institutes of Health (NIH) estimated annual budget, on topics ranging from cancer research, mental health, and infectious diseases, to aging, rare diseases, health disparities, and women’s health (2).

As the variation in NIH budgetary investments makes clear, public health and medical research are constructed by, and conducted within, an ecology of ideas—the etiology of disease, the concepts of both disease and health, prevention versus treatment, behavior change, drug safety and efficacy, moral priorities like disease control and the reduction of health disparities, etc.—concerning the foundational aspirations and intellectual suppositions of health research. In his 1910 JAMA Address titled “Imagination and Idealism in the Medical Sciences,” the physician and pathologist Christian Herter emphasized the importance of plasticity in science (3). Cultivating intellectual plasticity means that the foundational moral aspirations of science, along with the intellectual suppositions concerning the best strategies for realizing those ends (eg, promoting the health of a population), must be open to change and revision.

Herter’s insight is significant for understanding how public health’s “ecology of ideas” must evolve as the health challenges facing populations change through the different stages of “epidemiologic transition” (4). During the twentieth century, the United States transitioned from Stage 2 of the epidemiologic transition—The Age of Receding Pandemics—to Stage 4, known as The Age of Delayed Degenerative Diseases (5). This shift meant that the leading causes of death transitioned from early-life mortality caused by infectious diseases to the chronic diseases of late life. Early twentieth-century public health pioneers like C.-E.A. Winslow (1877–1957) and his mentor Hermann Biggs (1859–1923) developed the foundational moral aspirations and intellectual suppositions of public health’s “ecology of ideas” when sanitation science was critical for abating the high risks of early-life mortality. Winslow did acknowledge that public health was “protean,” by which he meant that the specific diseases public health focused on mitigating would change over time. For example, Winslow argued that once the aims of sanitation had been realized for a community, public health’s attention would turn to water-borne and insect-borne diseases. And “[a]s typhoid, cholera, plague and typhus fever approach the vanishing point, measles, pneumonia and influenza become relatively more and more important” (6).

But the flexibility inherent in Winslow’s “The War Against Disease” approach to health promotion was substantively more modest than the plasticity that Herter envisioned. For Winslow, protean public health meant that the sanitation of the environment could be superseded by the control of community infections as the first rank of public health problems once success with sanitation had been established. But this change still functioned within the “The War Against Disease” paradigm. To meet the health challenges of today’s aging populations, public health’s “ecology of ideas” must supplement the goal of disease control with what the gerontologist Alex Comfort (1969) (7) called the goal of “rate (of aging) control.” Although some aspects of geroscience may resonate with, and adequately function within, the presuppositions of the disease-model paradigm (eg, lifestyle modifications that help abate accelerated aging), Comfort’s aspiration to achieve rate of (aging) control requires transcending the central moral aspiration of the early twentieth-century public health pioneers (ie, disease control), as well as some of their central intellectual suppositions. For example, that public health, at least for older populations in developed countries, is “purchasable” or that behavior modification (eg, exercise, fasting, etc.) alone constitutes the most optimal and feasible way to promote health (vs the development of safe and affordable gerotherapeutics that retard biological aging).

Public Health and the “The War Against Disease”

Winslow’s 1903 article in The Atlantic Monthly entitled “The War Against Disease” (8) was written when infectious diseases caused high rates of early-life mortality. In the year 1900, life expectancy at birth in the United States (for all races and both sexes) was age 47.3 (9). The 3 leading causes of death in 1900 were pneumonia, tuberculosis, and diarrhea and enteritis, and 40% of those deaths were among children aged less than 5 years (10). Winslow’s title—“The War Against Disease”—clearly articulated the central aspiration of public health for the early twentieth-century- disease control. The goal of disease control was thus the foundational moral aspirational premise of public health’s “ecology of ideas.” This aspiration informed the creation, in 1946, of the Communicable Disease Center (CDC; in 1992, this was changed to the current name—Centers for Disease Control and Prevention). In 1946, the CDC’s primary mission was to prevent the spread of malaria by waging a war on mosquitoes. And Winslow’s “The War Against Disease” was then applied to chronic diseases, evidenced by the National Cancer Act of 1971 and President Nixon’s declaration of a “war against cancer” (11,12). The aspiration to eliminate cancer was reaffirmed yet again in 2008 when the National Cancer Institute set the Challenge Goal to eliminate the suffering and death due to cancer by 2015. And yet cancer still remains the second leading cause of death in the United States, responsible for an estimated 602 350 deaths in the year 2020 (13).

Winslow also proposed what was to become a foundational strategic premise of public health’s “ecology of ideas”—that the optimal strategy to achieve disease control is to conquer each specific disease, one at a time. Winslow remarked:

Each disease must be fought after its own kind. For smallpox, vaccination; for diphtheria, antitoxin inoculation; for typhoid fever, the protection of food supplies; for yellow fever, the destruction of mosquitoes; for tuberculosis, the disinfection of sputum; for cholera infantum, the cooking of milk. (8)

Winslow’s conception of public health was shaped by that of his mentor, Hermann Biggs, who championed a second strategic intellectual supposition of public health that “public health is purchasable.” Biggs was the general medical officer of the Department of Public Health for New York City and was in the October 1911 issue of the Monthly Bulletin for New York City’s Department of Health (14). Biggs argued that disease was mostly an avoidable state of affairs, and it persisted because of unfavorable economic and living conditions. For Biggs, the slogan “public health is purchasable” “expressed a truth which lies at the foundation of the entire public health movement” (14).

Sanitation science proved very valuable in helping to abate many of the health risks of early-life mortality. Biggs also championed a further strategic intellectual supposition that shaped public health’s “ecology of ideas” in the latter half of the twentieth century. And that was the insight that the public health strategies (eg, behavior change) employed against infectious diseases could also be employed to protect against the degenerative diseases of later life. Biggs remarked:

The future development of public health work will include the opening up of a field in which little or nothing has been done. Systematic attack will be made, principally, by education of the public in prophylactic measures, against those diseases in middle and later life which are not infectious and which have hitherto been regarded as entirely outside the sphere of public intervention. (14)

Taken together, the insights of Winslow and Biggs represent some of the foundational moral and intellectual suppositions of early twentieth-century public health. The “ecology of ideas” of early twentieth-century public health and medicine are shown in Figure 1.

The Epidemiologic Transition

The moral aspiration and intellectual suppositions of early twentieth-century pioneers in public health were shaped during what Abdel Omran (4) referred to as the second stage of the “epidemiologic transition.” That is, the stage where the highest mortality risks came from infectious diseases and were typically inflicted upon the young. But by the end of the twentieth century, the populations in developed countries had, due to improvements in public health, medicine, and material prosperity, aged. For example, by the year 2000, life expectancy at birth in the United States had risen to age 76.9 (15) (from age 47.3). Decades earlier, chronic diseases like heart disease and cancer had replaced infectious diseases as the leading causes of death. And declines in the death rate from these degenerative diseases in middle life and later ages pushed their mortality risks into more advanced ages (age 70+). So, by the end of the twentieth century, the population in the United States had transitioned from the second stage of the epidemiologic transition to the fourth stage—The Age of Delayed Degenerative Diseases (5). Olshansky and Ault (1986) describe the latter as the stage where “the major degenerative causes of death remain the major killers, but the risk of dying from these diseases is redistributed to older ages.”

Winslow’s foundational moral aspiration for public health, that war should be waged to control, if not eliminate, disease, was partly realized in the twentieth century. Smallpox was the only disease to be eradicated, but many other infectious diseases were successfully eliminated or at least brought under control in specific regions of the world. And although the degenerative diseases were not eliminated, preventative measures (eg, smoking cessation, exercise, and improved diet), coupled with improvements in early diagnosis and medical treatments, helped push the age of death from chronic disease into later ages.

Two empirical assumptions were implicit in the foundational moral aspiration of Winslow’s “The War Against Disease.” These assumptions were:

• (1) diseases could be eliminated, or at least controlled; and

• (2) abating disease risks would increase not only life expectancy but also healthy life expectancy.

The second empirical assumption was based on the presumption that the absence of disease could be equated with the presence of health. Eliminating smallpox and polio, for example, did increase the number of healthy years a population could expect to live. So, the presumption that disease control would always yield an increase in healthy life was a defensible empirical assumption to make during the second stage of the epidemiologic transition given the high prevalence of early-life morbidity and mortality. But this same empirical assumption cannot be made in Stage 4 of the epidemiologic transition. Preventing death from a specific type of cancer, like breast or colon cancer, in late life does not necessarily mean an extension of healthy life. In Stage 4 of the epidemiologic transition, the strategy of disease control faces significant limitations because of the biological reality of multimorbidity in late life. As Olshansky (16) notes, finding a cure for one of the late-onset diseases like cancer can mean that more debilitating diseases can become more prevalent because the hazard in old age is not so much that 1 disease displaces another but that the new diseases are often much more debilitating.

Increasing the Healthspan versus Lifespan

The intellectual presuppositions of early twentieth-century public health were developed during the second stage of the epidemiologic transition when infectious diseases posed high mortality risks to the young. It was also a time of limited scientific understanding, especially with respect to the biology of aging. In “The War Against Disease,” Winslow made an analogy between a candle’s propensity to blow out and the variation in mortality risks over the course of the human life span.

The flame, as it first catches, flutters feebly so that the least breath will quench it; and again when burned almost to the socket it flickers and easily goes out. Thus the body which in middle life may bear the severest shocks of sickness and privation, in infancy and in old age succumbs to but slightly unfavorable conditions. The extinction of life at the end of its natural cycle, after the course has been finished, and the allotted work done, can scarcely be regretted, but the lives cut off well before they have begun are an absolute loss to the community, of the extent to which most of us have little conception (8).

Winslow presumed the human life span was “fixed,” and that the healthspan and life span were either synonymous or expired simultaneously. Over the course of the twentieth century, significant scientific findings in the biology of aging revealed that aging is both a major risk factor for most diseases, frailty, and disability in late life, and, more importantly, aging is malleable versus immutable. Experiments in rats and mice in the 1930s demonstrated that aging is malleable and that caloric restriction could increase life span. Pioneering researchers in the biology of aging began to unlock the mysteries of the biology of aging which challenged the empirical validity of many of the foundational suppositions of early public health pioneers. Biggs’s contention that disease was mostly an avoidable state of affairs and that it persisted because of unfavorable economic and living conditions was no longer a defensible presumption for public health to espouse once the evolutionary causation of disease had been elucidated. In his 1963 book review of the life tables of England and Wales (1841–1960) entitled “The Truth about Death,” the British geneticist and polymath JBS Haldane noted that although hygiene had vastly lowered mortality in infancy and up to the age of 55 or so, there was little improvement at ages over 60. Haldane aptly perceived that “natural selection sees to it that genes causing early death or sterility are fairly rare. On the other hand, post-reproductive mortality seems to be genetically determined to a large extent” (17).

The potential medical significance of aging research was impeded by public health’s original “ecology of ideas,” an ecology that was susceptible to many cognitive blind spots because of its fixation on controlling infectious disease risks. For example, the fixation on mitigating the proximate causation of disease (both infectious and chronic) meant that the identification of, and aspiration to mitigate, the evolutionary causation of disease was mostly neglected. Perhaps the most significant aging “blind spot” in public health’s “ecology of ideas” was solidified in the mid-twentieth century when causes of death were reclassified. “Since 1951, the year all state and federal agencies in the United States were required to adopt a standard list of contributing and underlying causes of death, no one in the United States died from ‘old age’” (18). This cemented the marginalization of aging research to disease research since the public expected medical research to yield “life-saving” interventions, and if no one died from aging, then there is no pressing rationale for prioritizing aging research over disease research.

Despite the Herculean intellectual challenges geroscience faced with respect to competing against research on specific diseases, the clinical relevance of geroscience began to take shape during the 1980s, as the “era of genetic manipulations in aging” (19) in invertebrates and mice demonstrated that genetic mutations lead to increased life span. And now geroscience has entered the exciting stage of pharmacological and pharmaceutical interventions in aging with the launch of TAME (Targeting Aging with Meformin), the largest and most public clinical trial targeting the aging process in humans (20). The history and evolution of clinical trials in the United States are shaped by public health’s disease control paradigm. And thus, some aging scientists have contended that it is best to construe aging itself as a disease in order to buttress the prominence of geroscience, whereas others have reservations about such a tactic. The stakes in such debates are much more significant than just semantics, for they can have profound implications with respect to the plasticity of science and the budgetary implications that flow from its plasticity (or rigidity).

The future health of aging populations is contingent upon public health’s ability to transcend the limitations of the original “ecology of ideas” that emerged during The Age of Receding Pandemics. Herter was arguably a century ahead of his time when he conjectured, in 1910, that “progress in the medical sciences depends in a remarkable degree on discoveries made by indirect methods—that is, by not looking to the immediate relief of disease” (1). Key discoveries in aging research—ranging from caloric restriction in mice and the sequencing of the genomes of exceptionally long-lived species (eg, naked mole rat and bow head whale) and people (centenarians and supercentenarians), to identifying the biomarkers of aging and the testing of gerotherapeutics in humans (eg, metformin and rapamycin)—may lead to the most significant public health interventions of the twenty-first century. And none of these discoveries were, strictly speaking, research on pathology.

Conclusion

Although Table 1 shows the dominance the disease control paradigm still retains in the “ecology of ideas” of public health and medicine, the significance of the biology of aging is apparent in many of the top 20 research-funded areas. For example, the National Cancer Institute (21) identifies advancing age as the most important risk factor for cancer overall and for many individual cancer types. Aging is also very significant to women’s health as women live longer than men in most areas of the world, and comprise the majority of older persons, especially at more advanced ages (22). Compared with age-matched men, women tend to have poorer health status (ie, they are more frailer) (23). Aging is also a major risk factor for brain disorders like Alzheimer’s disease and severe COVID-19 (eg, hospitalization and death).

Winslow’s early twentieth-century understanding of public health as the “art and science of preventing disease” prioritized the means of sanitation of the environment, control of community infection, education about personal hygiene, and the early diagnosis and preventative treatment of disease. This approach was very successful in controlling the infectious disease risks that caused early-life mortality in the first half of the twentieth century. And by the end of the twentieth century, “The War Against Disease” had helped to redistribute the age of death from degenerative diseases to later ages (age 70+). But now public health must take seriously the goal of improving the quality of life of older persons, of increasing the human healthspan (vs delaying the age of death by trying to eliminate specific diseases). Biggs’s (1911) contention that “public health is purchasable” must be invoked not simply to abate the health risks of unfavorable economic and living conditions, but to also abate the health risks imposed by a Darwinian evolutionary history that prioritized reproduction over healthy longevity. Geroscience and the goal of rate (of aging) control represent the kind of plasticity in science that Herter celebrated in his 1910 JAMA Address.

Acknowledgments

I am grateful to 2 referees and an Associate Editor of the journal for their helpful feedback and suggestions on an earlier version of this paper.

Funding

None declared.

Conflict of Interest

None declared.

References