Core Principles of Evolutionary Medicine
Big Ideas function as the “conceptual Velcro for a topic of study. They connect discrete knowledge and skills to a larger intellectual frame and provide a bridge for linking specific facts and skills. A focus on these larger ideas helps students to see the purpose and relevance of content.
McTighe & Wiggins, 2004, p. 69It is important to focus curriculum around big ideas that make up a field. As the quote by Jay McTighe and Grant Wiggins above suggests, these ideas that serve as “Velcro” for all the smaller bits of information a student will learn. With this educational principle in mind, an expert panel was used to identify what the big ideas are for evolutionary medicine – the core principles. Fourteen core principles of evolutionary medicine were agreed upon by an international group of 37 experts through a Delphi study. These represent a valuable framework for thinking about important concepts for an understanding in evolutionary medicine.
Core Principles of Evolutionary Medicine that 80% of the experts agreed on as somewhat or very important. Table adapted from Grunspan et al. 2018.
| Topic | Core principle |
|---|---|
| Types of explanation (question framing) | Both proximate (mechanistic) and ultimate (evolutionary) explanations are needed to provide a full biological understanding of traits, including those that increase vulnerability to disease. |
| Evolutionary processes (evolution I) | All evolutionary processes, including natural selection, genetic drift, mutation, migration and non-random mating, are important for understanding traits and disease. |
| Reproductive success (evolution I) | Natural selection maximizes reproductive success, sometimes at the expense of health and longevity. |
| Sexual selection (evolution I) | Sexual selection shapes traits that result in different health risks between sexes. |
| Constraints (evolution I) | Several constraints inhibit the capacity of natural selection to shape traits that are hypothetically optimal for health. |
| Trade-offs (evolutionary trade-offs) | Evolutionary changes in one trait that improve fitness can be linked to changes in other traits that decrease fitness. |
| LHT (evolutionary trade-offs) | Life history traits, such as age at first reproduction, reproductive lifespan and rate of senescence, are shaped by evolution, and have implications for health and disease. |
| Levels of selection (evolution II) | Vulnerabilities to disease can result when selection has opposing effects at different levels (e.g. genetic elements, cells, organisms, kin and other levels). |
| Phylogeny (evolution II) | Tracing phylogenetic relationships for species, populations, traits or pathogens can provide insights into health and disease. |
| Coevolution (evolution II) | Coevolution among species can influence health and disease (e.g. evolutionary arms races and mutualistic relationships such as those seen in the microbiome). |
| Plasticity (evolution II) | Environmental factors can shift developmental trajectories in ways that influence health and the plasticity of these trajectories can be the product of evolved adaptive mechanisms. |
| Defenses (reasons for vulnerability) | Many signs and symptoms of disease (e.g. fever) are useful defenses, which can be pathological if dysregulated. |
| Mismatch (reasons for vulnerability) | Disease risks can be altered for organisms living in environments that differ from those in which their ancestors evolved. |
| Cultural practices (culture) | Cultural practices can influence the evolution of humans and other species (including pathogens), in ways that can affect health and disease (e.g. anti-biotic use, birth practices, diet, etc.). |
The full wording of each principle was approved by at least 80% of panelists after the fourth round of the Delphi survey. 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. Evolution I and Evolution II include general evolutionary principles, with the principles in Evolution II more complex than those in Evolution I. 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.
For an expanded version with narrative commentary see: Nesse, Randolph M. (2019). Core Principles for Evolutionary Medicine. In M. Brüne & W. Schiefenhövel (Eds.), Oxford Handbook of Evolution and Medicine. London ; New York: Oxford University Press, pp. 3-43.
To learn more or contribute to the project, please get in touch with Daniel Grunspan.