Lack of consensus on an aging biology paradigm? A global survey reveals an agreement to disagree, and the need for an interdisciplinary framework

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Highlights

  • A recent symposium debate highlighted disagreements and confusion in aging biology.

  • Symposium participants followed up by completing an online survey.

  • Survey results show little common ground on most questions in aging biology.

  • However, there is a near-consensus that aging is heterogeneous and multifactorial.

  • Work is needed to achieve a common paradigm in aging biology.

Abstract

At a recent symposium on aging biology, a debate was held as to whether or not we know what biological aging is. Most of the participants were struck not only by the lack of consensus on this core question, but also on many basic tenets of the field. Accordingly, we undertook a systematic survey of our 71 participants on key questions that were raised during the debate and symposium, eliciting 37 responses. The results confirmed the impression from the symposium: there is marked disagreement on the most fundamental questions in the field, and little consensus on anything other than the heterogeneous nature of aging processes. Areas of major disagreement included what participants viewed as the essence of aging, when it begins, whether aging is programmed or not, whether we currently have a good understanding of aging mechanisms, whether aging is or will be quantifiable, whether aging will be treatable, and whether many non-aging species exist. These disagreements lay bare the urgent need for a more unified and cross-disciplinary paradigm in the biology of aging that will clarify both areas of agreement and disagreement, allowing research to proceed more efficiently. We suggest directions to encourage the emergence of such a paradigm.

Introduction

The authors were all participants at the Biology of Aging Symposium: Understanding Aging to Better Intervene, held November 9–11, 2019 in Montreal, Quebec. The symposium featured 44 speakers with a diversity of expertise related to aging, including basic aging biology, translational geroscience, geriatric medicine, nutrition, immunosenescence, evolutionary ecology, demography, statistics, systems biology, epidemiology, and complex systems theory. During the course of the symposium, a debate was held on the question, “Do we know what aging is?” with Brian Kennedy ostensibly arguing the “Yes” side and Alan Cohen ostensibly arguing the “No” side. There was dynamic audience participation. Most participants agreed that the debate and the subsequent extensive discussion involving many participants were striking in how they highlighted the lack of a clear consensus paradigm (Kuhn, 1970) in the field, and collectively we agreed it would be important to describe this for the research community in our field.

Accordingly, we designed a survey that was sent to participants of the symposium, both invited speakers and students/other participants. The survey was meant to capture the opinions on both the key points of disagreement and basic features of aging in general. All participants who responded to the survey are co-authors. We use the term “aging” to refer to “aging biology,” though, as will be shown, some but not all participants felt that aging biology cannot be understood in isolation from psychological, social, and cultural factors.

Philosophers of science generally believe that at least some aspects of a shared paradigm or worldview are often critical in helping a field advance, though the precise nature and role of such paradigms is debated (Kuhn, 1970; Lakatos, 2014). Beyond the biology of aging that is our focus here, it has been argued that there is a broad gerontological paradigm spanning from biology to the social sciences (Ferraro, 2018), with six key features: causality, life course analysis, multifaceted change, heterogeneity, accumulation processes, and ageism. Our discussions at the symposium showed no consensus on questions relating to ageism and causality, but generally supported the other four proposed features. Nonetheless, the broad areas of disagreement shown below will pose challenges for the field, and the nature of a paradigm is likely to be quite different for aging biology than in gerontology more broadly. If we cannot agree on what aging is (definitions and mechanisms), how can we identify it, measure it, or know if we are measuring it (Belsky et al., 2015; Calimport et al., 2019; Horvath, 2013; Levine, 2013)? How can we evaluate potential anti-aging interventions (Justice et al., 2018)? How relevant are findings from other species in terms of understanding human aging (Austad, 2010; Jones et al., 2014)? We do not believe it is possible at this point to propose a paradigm that would be broadly accepted in the field; accordingly, the best we can do is to note the important differences and try to propose a roadmap for what would be needed to achieve consensus on key questions.

Section snippets

Survey

We used the tool Google Forms to distribute a survey to all participants at the symposium (44 invited speakers, 2 organizers, 14 students, and 11 others). The survey collected the following information: (1) name; (2) demographic data (sex, country of origin, career stage) (3) domains of expertise (multiple responses permitted); (4) Likert-scale and other limited response questions (see below); and (5) a single open-ended question, “In no more than three sentences or 1000 characters, please

Results

Thirty-seven researchers/students responded to the survey (the authors of this paper). Demographically, 27 of 37 respondents were male, with origins in 18 different countries. No country had more than 3 respondents except Canada, which had 14, though it is worth noting that some respondents marked their current country of residence, some marked their country of origin, some marked both, and some left the field blank. Respondents were at a variety of career stages as early as post-bachelor’s,

Discussion

The results of our survey undeniably confirm the impression at the symposium: there is no clear consensus in the field of aging biology, even on the most fundamental questions. There was a near-consensus (but not complete) that aging is heterogeneous, reflected in a clear preponderance of respondents considering that aging does not proceed uniformly across tissues and that aging cannot be measured with a single, unidimensional metric. The only other question with such a clear preponderance of

Acknowledgements

A.A.C. is supported by a Canadian Institutes of Health Research (CIHR) New Investigator Salary Award and is a member of the <GS2>Fonds de recherche du Québec - Santé (FRQ‐S)<GS2> funded Centre de recherche du CHUS and Centre de recherche sur le vieillissement, as well as by a CIHR project grant (153011). A.M.S. is supported by a DECRA fellowship from the Australian Research Council (DE180101520). VG and VNG are supported by grants from US National Institutes of Health. D.F. is supported by NIH

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