Evolutionary theory can inform medical practice

Examples of other fields that have used this method to identify core principles include clinical pharmacology and therapeutics [ 40 ], family medicine [ 41 ] and biomedical laboratory science [ 42 ]. The Delphi method starts with an initial question and uses feedback from an expert panel to gain resolution. This method employs a specific communication structure where panelists do not directly communicate with one another, but instead send responses to the research team.

This structure allows consensus seeking to utilize a variety of opinions, while excluding the distorting influence of dissent or agreement that may occur due to social pressures, such as influence from individuals who may have higher status [ 43 , 44 ]. The Delphi method often starts with a survey requesting open-ended responses from panelists about the topic of interest. Upon receiving and analyzing responses to this initial survey, the research team sends a summary back to each panelist along with a second survey asking panelists to evaluate responses from the first survey.

This process is performed iteratively in additional surveys until there is either consensus agreement amongst the panel, or a lack of consensus that identifies the reasons for disagreements. The current study followed this general format using four surveys to elicit core principles in evolutionary medicine.

Panel selection is a critical component of a Delphi study. Panelists must represent diverse opinions from qualified experts. Evolutionary medicine is a transdisciplinary field, with contributions from biologists, anthropologists, and human and animal medical professionals, among others.

Because the validity of Delphi results relies on having diverse experts on the panel, panel construction was performed with the transdisciplinary nature of evolutionary medicine in mind. To begin identifying panelists, six recognized experts in the field were invited via e-mail to each nominate individuals to participate in the Delphi panel. This invitation specifically asked these experts to identify other individuals who have a good grasp of the field, including both individuals who have a broad view and those whose perspective is more specialized.

In total, five experts responded to this e-mail and made 35 total nominations with 24 unique individuals listed. Because a larger panel specifically constructed to achieve diversity in expertise and background was desired, the research team then identified 32 more individuals based on their active participation in the EvMed community through publications and participation in the International Society for Evolution, Medicine and Public Health conference ISEMPH.

All six of the initial experts were also included on this panel, either through being nominated initially by one of the other experts or through their inclusion in the list of 32 additional panelists. This process aimed to identify panelists who would provide perspectives that were diverse by fields, geographic locations and genders. Members of the same institution of the team that conducted the survey were not included in the panel to minimize bias because one of the study authors was their supervisor, to avoid over-representation of local points of view, and because local conversations and relationships at the university could erode the benefits of the anonymous nature of the Delphi structure.

In total, 56 panelists were identified and invited to participate in the Delphi study. The final panel consisted of 19 females and 37 males.

At the time of the study, 40 panelists worked in North America, 12 in Europe and four in other continents. While we did not collect data on the age of our panelists, we can look at the number of years since their first publication to understand the academic age of our panel. The average number of years since the first publication of panelists was The breadth of expertise in the panel is hard to define, as many if not all panelists have diverse areas of expertise, and are hard to categorize.

A summary of these classifications, along with a co-authorship network of panelists, display the heterogeneity in expertise and publication histories Supplementary Material. Four sequential online surveys were administered to all 56 panelists. Two members of the research team DZG and MEB independently read all responses to the first survey and compiled a list of emergent core principles. These two lists were very similar, with few areas of disagreement, mainly about the scope of different principles; some principles could be subsumed within larger ones.

Disagreements about the identification and hierarchy of distinct principles and their wording were resolved through discussion and further evaluation of panelist responses by the entire research team DZG, RMN, MEB and SEB. Panelists evaluated these core principles and sub-principles in the second survey. Panelists were asked to rate the principles based on their importance to evolutionary medicine, and were given the option to comment on each principle.

These comments could include why they rated a principle as they did, thoughts about specific wording, or about the initial categorization of principles as a core or a sub-principle. The subsequent two surveys no longer included the sub principles from round two, and asked panelists to rate and comment only on the updated lists of potential core principles.

At each stage, the research team modified principles when several panelists made similar comments, or if a single comment illuminated inaccuracies or obscurity in the wording of a principle. A full over-view of the methods and survey results are provided in the Supplementary Material.

Table 1. Overview of the four Delphi surveys including their purpose, types of participant response, as well as the number of responses out of the 56 panelists each survey was sent to. Panelists rated the longer statements e. The research team grouped these principles based on how similar they were to one another after the completion of the study to help organize the principles based on similarity.

These groups included: i Question framing includes one principle about the different types of questions addressed in biology; ii Evolution I and Evolution II, which were general evolutionary principles, with the principles in Evolution II more complex than those in Evolution I; iii Evolutionary-Tradeoffs includes both Trade-offs and Life History Theory, which are closely related concepts as they apply to health; iv Reasons for vulnerability include the two principles that represent direct evolutionary explanations for disease and v Culture includes the one principle that discusses the impacts of cultural practices.

Table 2. Core Principles of Evolutionary Medicine. The research team labeled each principle with a topic name and grouped these principles based on their relation to one another after the completion of the study to help organize the principles. Descriptions of the groups are as follows: Question framing includes one principle about the different types of questions addressed in biology. Evolutionary-Tradeoffs includes both Trade-offs and Life History Theory, which are closely related concepts as they apply to health.

Reasons for vulnerability include the two principles that represent direct evolutionary explanations for disease. Culture includes the one principle that discusses the impacts of cultural practices.

Importance rankings for the core principle that achieved consensus in the third or fourth survey. The format of the final core principles condenses broad abstract ideas into a necessarily short and condensed form. Different opinions about optimal wording reduced agreement between panelists on the importance of several principles. While consensus for 14 core principles was reached, persistent confusion and disagreements arising from the wording suggested a need for elaboration on each.

Below we expand on each principle to elaborate those meanings, and illustrate some of the common comments and issues of panelists. Understanding evolutionary medicine requires understanding the kinds of questions asked in the field, especially the difference between proximate and evolutionary explanations. Tinbergen formulated a framework including four categories of explanations for traits [ 47—49 ].

Regardless of wording, this principle provides an essential foundation for recognizing the several complementary kinds of explanations that can be used across the life sciences. Many panelists made comments about the importance of recognizing the contributions of all four processes in order to avoid the error of considering only natural selection.

Understanding evolution in depth is fundamental to evolutionary medicine, and this principle, while written to be general, captures how an understanding of all evolutionary processes is central to evolutionary medicine. Reproductive success Initial survey responses included both general comments about the process of natural selection, as well as comments that specifically emphasized that natural selection selects for reproductive fitness, which can occur at the expense of health and longevity.

While we initially considered these over-lapping principals an understanding of natural selection free of misconceptions should include knowing that reproductive success can be at the expense of health and longevity , panelist comments and ratings indicated that a separate focus on reproductive success is an important and distinct core principle.

Like the principle for reproductive success, sexual selection can be considered nested within a general understanding of natural selection. However, most panelists recommended including sexual selection as an important separate core principle. Understanding how sexual selection shapes differences in male and female physiology and behavior is important for understanding differences in health risks.

They include path dependence, the inevitability of mutations, trade-offs such those seen in antagonistic pleiotropy and others. This is a principle with large scope, and large ideas in evolutionary medicine nested within it. The vague wording of this principle led to some concerns about its importance, but most panelists saw this idea as an important idea for the field.

Trade-offs The role of evolutionary trade-offs in explaining disease vulnerability is a central and important core principle for evolutionary medicine.

The principle is intimately tied to Life History Theory, and has been a major and influential idea in Evolutionary Medicine and beyond [ 10 ]. Indeed, some panelists felt that LHT was a nested principle that could be understood through trade-offs, while others saw this relationship in the inverse trade-offs as a subset of LHT. While this principle achieved high agreement in its current form, it could be somewhat misleading by implying that trade-offs must include two traits.

For instance, lower levels of gastric acid reduce ulcers at the cost of increased risk of infection. The evolution of life history traits is intricately tied to many aspects of health.

Understanding the evolutionary origins of human life history traits such as altriciality, short interbirth intervals and prolonged maturation time are critical for understanding life-stages and health outcomes.

Initially, because of the close tie to trade-offs, LHT was listed as potentially over-lapping with trade-offs. However, responses in subsequent surveys indicated a consensus among panelists that LHT is important and unique enough to be listed as a distinct core principle. Responses to the initial survey suggested listing somatic selection in cancer, genetic conflicts and mentions of group selection as core principles.

While these concepts differ in their implications for health and disease, they share a larger focus on thinking about selective dynamics at levels other than the individual. That is, natural selection can act on replicating entities at different levels, and when the selection forces differ between these levels, conflict can occur. Thus, understanding cancer through an evolutionary lens requires considering the how selective dynamics at the cellular level interact with those at the individual level.

Similar reasoning is needed to understand the evolutionary dynamics of genetic element replication at a cost to the cell.

Phylogeny While neglected early on in evolutionary medicine, tracing phylogenetic relationships is a major area of evolutionary research that is becoming increasingly important for evolutionary medicine.

While phylogenies often focus on the relation between species, comments from panelists indicated that phylogenies of populations, different molecules or traits and pathogens, are all useful for medical research.

This core principle encompasses the importance of understanding the relatedness between any replicating entities. Coevolution Understanding many human diseases requires appreciating the coevolution between pathogens and defenses against those pathogens. Indeed, most anti-biotics are produced by bacteria as a result of coevolutionary competitions with viruses and other bacteria. Notably, coevolution is also an important consideration for the emerging field investigating the roles of microbiomes in health.

Plasticity Plasticity is a general capacity of living organisms—phenotypes shift in the course of development or over shorter time frames as genes interact with varying environments.

Plasticity is important to evolutionary medicine because selection shapes mechanisms that regulate plasticity that can influence disease risks.

Especially important for medicine are mechanisms that shift development in response to environmental cues detected during developmental windows. Evolved defenses as a concept has a more narrow focus than some of the other principles, but it is centrally important to how evolution can inform medicine. Understanding signs and symptoms of disease as protective responses has implications for treatment. How selection shapes systems that regulate defense expression the Smoke Detector Principle was considered as a separate principle but was incorporated into this larger category.

Many panelists mentioned the idea of evolutionary mismatch in the first survey. Comments throughout the Delphi study necessitated edits to ensure that this principle captured the various ways mismatch can occur e.

It is also important to avoid the incorrect assumption that humans are adapted to a single environment, and to recognize that mismatch may result from migration between stable environments [ 35 ]. Understanding any aspect of human traits requires considering the importance of culture and cultural practices. While a general consideration of human culture is critical to understanding human evolution [ 50 ], it is also important in many aspects of human health.

This importance includes the evolutionary impacts of medical practices such as anti-biotic use, chemo-therapy regimens and caesarean sections. This principle can incorporate the importance of many behaviors and traits not-attributable to genetics, but possibly involving cultural practices.

Indeed, while these principles did not make the final list, many of them may still be of interest to instructors in creating learning goals in courses focused on related topics. Notably, some of the principles in this list could be considered more uniquely relevant to evolutionary medicine than other broader core principles. It is noteworthy that many of these specialized principles can be derived from the more generalized core principles, so it is possible that they were considered too specific to be a core principle.

Table 3. It became apparent early on in the Delphi process that the network of core principles contained hierarchies; some specified ideas listed by panelists could be understood through an understanding of other broader ideas.

These broader ideas tended to be derived from general evolutionary biology or medical sciences. Comments from panelists throughout the Delphi process illustrated the blurred line between evolutionary medicine and general evolutionary biology or medical sciences.

The result that the identified core principles trended toward broader ideas lends credence to evolutionary medicine being a subfield of evolutionary biology, with critical inputs from other disciplines. As an emergent and growing field, this may change over-time. These core principles could be especially useful for creating learning objectives for courses in evolutionary medicine in a way that aligns with national recommendations for teaching big ideas, and not isolated facts [ 1 ]. The principles elicited came from the evolutionary medicine community, and they represent ideas central to the field with broad applications.

With this in mind, the core principles elicited here should not be interpreted as prescriptive, and should instead be thought of as a recipe for the development of learning objectives that encourages users to add or subtract core principles to their own needs.

Similar to other efforts to present a set of core principles [ 45 , 51 , 52 ], the goal is to provide a resource for instructors, but not meant to constrain them. Further, as we highlighted, disagreements among panelists about some of the principles highlight that core ideas in this field will continue to evolve over-time. Although there have been previous efforts to delineate the important concepts in evolutionary medicine, our efforts represent the first systematic study to do so with the involvement of over 50 individuals.

The list of core principles is generally consistent with those emphasized in previous articles based on less systematic methods [ 25 , 29 , 31 , 53 ]. While these articles did not necessarily aim to define core principles with the same definition adopted here, or have a focus on being exhaustive, it is nonetheless instructive to examine the over-lap between list here and principles discussed in previous work.

By doing so, we get some idea of the reliability of the results. Table 4 lists principles, learning goals, and suggested biomedical examples of evolutionary concepts as worded in previous articles. We denote in the table how these ideas over-lap with the core principles elicited here. While many of these are directly congruent with the core principles, others are more specific or even common misconceptions related to a core principle.

We would argue that by the nature of our study design, the community of evolutionary medicine can have more confidence that our core principles are a consensus view.

Thus, we hope that it can spur greater emphasis on these topics in evolutionary medicine courses so that there can be greater commonalities between evolutionary medicine courses taught by different instructors at different institutions.

Table 4. Principles, learning goals, and concepts as described in previous articles about evolutionary medicine. Defined partially by their explanatory breadth and importance to the field, core principles also provide a framework that can organize research.

The framework of core principles provided here can help clarify connections between ongoing research that may be based on larger ideas, and not on topics or methodology. Organizing research by large ideas is not novel; conference sessions have been organized on ideas such as life history theory and trade-offs.

However, making the network of core principles more explicit can catalyze further connections between research that applies a shared principle without sharing topical focus or methods, and could expedite new and exciting research avenues. We hope that instructors designing new courses or revising current courses in evolutionary medicine consider these larger principles when designing learning goals for students.

Instructors are encouraged to incorporate these principles in ways that incorporates their own experience and expertise, and the unique goals of their own curriculum and institutions. Disciplinary core principles help align classroom contents to the most pertinent material, are teachable at variable depths, and have high connectivity to other ideas and areas of content.

For these reasons, core principles can provide crucial foundations for thinking about learning goals in evolutionary medicine curricula. Evolutionary medicine is a young field that is growing fast along with many new courses in university curricula, new Centers and Institutes, and a thriving international society evolutionarymedicine.

Healthy growth of this field will be supported by effective pedagogy that starts with decisions about which principles are most important for students and professionals to understand, and focuses curricula on those principles.

Core principles provide a scaffolding to organize a growing array of facts and concepts. This organization is of great use in educational contexts, and may even help speed learning in medical curricula by clarifying the connections among thousands of otherwise unrelated facts.

The validated list of core principles in evolutionary medicine presented here provides a starting point for teachers, students and current and future researchers. Box 1. Big ideas are transferable beyond the scope of a particular unit…Big ideas are the building material of understanding. Each integrates many different findings and has exceptionally broad explanatory scope. We would especially like to thank the panelists for contributing their time and effort in making this research possible.

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The HapMap is important because genomes of any two humans differ only by 0. Researchers can use the general markers from the HapMap to narrow down their searches to areas of variation. An important key to drawing useful information from genomic data is the ability to link a genotype to a phenotype. This is a difficult problem for several reasons: genomic data are not usually collected from a specific individual with an extensive health history; family medical histories are rarely complete; environmental conditions vary between populations, etc.

One approach to deal with this issue is the use of large, long-term studies of specific populations. Initiated in to investigate the causes of heart disease and stroke, the project collected data on more than 5, people living in Framingham, Massachusetts.

In addition to birth, marriage, reproduction, and death data, the participants were given physical exams and lifestyle interviews. Follow-up physicals were given every 2 years. This study allowed researchers to identify the major environmental risk factors for cardiovascular disease, such as smoking and high blood pressure. Because of the extensive data collected for the project and the virtually unprecedented length of the study, the FHS is incredibly valuable to medical researchers.

The data are now being mined by groups researching other diseases such as obesity and eye and lung diseases. Other studies of large or multi-generational cohorts are also under way using different populations. He is enthusiastic about the concept of applying evolutionary principles to cohort data such as that generated over nearly six decades in the FHS. Govindaraju and his colleagues have organized a working group to explore the FHS from an evolutionary viewpoint.

The group proposes to look for microevolutionary changes in the study population and to use the extensive medical data to correlate differences in genomic inheritance and phenotypic outcomes. Given the vast quantities of data available because of the genomics revolution and multi-generational, longitudinal clinical cohorts such as the Framingham Heart Study, it has become increasingly clear that the analysis of new and existing data from an evolutionary perspective promises to yield important insights into long-standing questions about human physiology and pathophysiology.

Combined with the development of new technologies that have given us entire genomes and the tools with which to study them, these vast data sets have the potential to launch an evolutionary medicine revolution. It should come as no surprise that evolutionary medicine comes with a unique set of ethical issues. A field that encompasses so many aspects of who we are as individuals and has the power to provide better health to so many people also has the potential to be abused in a variety of ways.

Positive applications such as personalized medicine, in which an individual would receive the most beneficial medical treatment based on his or her genomic makeup, hold great promise for improving the efficacy of medical care. However, it is no great stretch to imagine that genetic information about individuals could be misused outside of the medical realm. Communication of complex evolutionary medicine concepts to the general public will be fraught with cultural perspectives, biases, and historical antagonism, and miscommunication could have serious consequences for individuals and society.

Privacy concerns are a major issue. Also, the use of particular populations in studies is a double-edged sword. In some cases, researchers can learn a great deal by studying a particular group whose members share a lifestyle or ancestry.

But how can that group be certain that the information will not be used against them, by insurance companies, for example? On the other hand, if beneficial information is gleaned from one group, how is that benefit made available to other groups who were not studied?

Another important issue to consider is the concept of race Kittles and Weiss Particularly in the USA, the sensitive nature of this issue cannot be overstated. The genetic concept of race and the social concept of race are not the same. In colloquial use, the term race designates a group of people based on their appearance and culture. Among the research community the definition of race has not been consistent or well defined. Scientifically, race correlates roughly with shared genetic ancestry usually based on geographic proximity, but even these parameters fail to clearly delineate groups.

There is some debate as to whether race is a legitimate biological concept at all. Social concepts of race also influence how research is done by biasing selection of populations to be sampled, methodologies, and other aspects of research. Paradoxically, some diseases are associated with socially defined races, such as Tay—Sachs disease in the Ashkenazi Jews, making it necessary to take into account these social groupings in conducting research.

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Nature ;— Bats are natural reservoirs of SARS-like coronaviruses. Science ;—9. Wickelgren I. Can worms tame the immune system. Download references. The authors would like to thank the organizers and participants of the Evolution in Contemporary Human Populations: Medical, Genetic and Behavioral Implications meeting at NESCent for providing access to the meeting and supporting information, and reviewers for their helpful comments.

Main St. You can also search for this author in PubMed Google Scholar. Correspondence to Kristin P. Reprints and Permissions. Hood, E. Evo Edu Outreach 1, — Download citation. Received : 27 August Accepted : 11 January Published : 13 February Issue Date : April Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative.

Skip to main content. Search all BMC articles Search. Download PDF. Abstract Modern evolutionary research has much to contribute to medical research and health care practices. Evolution and Medicine Evolution has not traditionally been considered to be an important aspect of medicine, and medical practitioners and researchers have not traditionally approached their work from the perspective offered by evolutionary biology.

Stearns, Nesse, and David Haig of Harvard University eloquently explain the importance of evolutionary trade-offs in the initial chapter of Evolution in Health and Disease Stearns and Koella : No trait is perfect.