Evolutionary medicine (Darwinian medicine)
Evolutionary medicine, also known as Darwinian medicine, is an innovative approach to understanding health and disease through the lens of evolutionary biology. It investigates the biological origins of diseases and human health, applying evolutionary principles to a range of medical topics, including aging, immunity, cancer, and infectious diseases. By examining how natural selection influences human vulnerability to illnesses, researchers in this field seek to uncover insights that can enhance disease prevention and treatment strategies.
The field emerged from the foundational work of Charles Darwin and has evolved since the early 1990s, when researchers like George Williams and Randolph Nesse highlighted the relevance of evolutionary theory to modern medicine. Evolutionary medicine is seen as complementary to traditional medical practices, rather than a competing alternative. This perspective allows for a deeper exploration of why certain genetic traits persist, even when they may appear maladaptive, such as narrow birth canals or genetic predispositions to diseases.
Key areas of research include population genetics, which studies genetic variation within populations, and pharmacogenomics, which examines how genes affect individual responses to drugs. As evolutionary medicine continues to develop, it holds promise for informing public health policies and enhancing our understanding of the interplay between human biology and environmental changes. Despite being a relatively nascent field, it aims to provide critical perspectives that could shape the future of healthcare.
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Evolutionary medicine (Darwinian medicine)
Evolutionary medicine, also known as Darwinian medicine, is an emerging approach to medicine and health care that draws on known and theorized principles of evolutionary biology to better understand and prevent diseases affecting humans. Darwinian medicine broadly encompasses research focused on the biological origins of both human health and the diseases that threaten it. Researchers apply these principles to a broad set of health-related issues including aging, immunity, cancer, infectious agents, reproductive health, human microbiomes, dietary factors, and the emerging field of personalized medicine.
Though it is sometimes characterized as a form of alternative medicine, experts and clinicians stress that evolutionary medicine is more accurately viewed as an adjunct to mainstream medicine rather than a rival or alternate system. The goal of Darwinian medicine is to equip medical researchers and healthcare professionals with insights into health and disease drawn from evolutionary factors and features. Proponents of Darwinian medicine generally believe that the process of evolution generates many clues as to how certain diseases and health conditions can best be treated or prevented.
Background
Evolutionary biology is rooted in the groundbreaking work of British naturalist Charles Darwin (1809–1882), who is widely recognized as the founding figure of evolutionary theory. Darwin’s ideas about evolution, summarized in the well-known phrase “survival of the fittest,” hold that the plants and animals that make the most effective adjustments to their environment survive and reproduce at the highest rates. Over time, the plant and animal species with the strongest survival characteristics thrive, while those with weaker survival characteristics die off.
Darwin famously advanced the theory of evolution in his seminal book On the Origin of Species, which was first published in 1859. Considered the founding document of evolutionary biology as a distinct scientific field, the book created a foundational framework for the core principles of evolutionary theory. These principles are often summarized as the “VIST” principles: variation, inheritance, selection, and time.
The variation principle holds that the genetic differences found in all members of a particular species leads to a distinctive set of physical characteristics and abilities that are unique to each individual. Inheritance describes the transferable nature of these characteristics and abilities from parents to offspring. Parents tend to pass their unique physical characteristics and abilities on to their children. Selection notes that some such characteristics equip certain individuals with a superior ability to survive or thrive within its environment, and the genes related to those superior characteristics tend to become more dominant in species over time since they are associated with higher rates of survival and reproduction. Changes occur slowly but consistently over the final principle, time. Genetic variations that support success, as defined by survival and reproduction, accumulate in species as time progresses.
Scientists first began to apply evolutionary theory to diseases around 1880, investigating how the principles of evolution affect pathogen development and the evolutionary relationships between pathogens and human hosts. Between approximately 1880 and 1940, multiple researchers endeavored to develop models to explain how diseases developed destructive traits that persist through the process of natural selection.
Contemporary schools of evolutionary medicine began to emerge in 1991 when researchers George Williams (1926–2010) and Randolph Nesse (1948– ) published their influential article “The Dawn of Darwinian Medicine” in the Quarterly Review of Biology. In the article, Williams and Nesse explained their hypothesis that human proneness to disease is a direct result of humankind’s evolutionary history, and evolution does not function to generate improvements in an organism’s lifelong health profile but instead exists solely to pass strong and evolving genes down through successive generations. The terms evolutionary medicine and Darwinian medicine are usually used interchangeably. Though the two concepts are virtually indistinguishable from each other, some models describe Darwinian medicine as a specialized sub-branch of evolutionary medicine that draws exclusively on evolutionary principles specific to Darwinist schools.
Observers also stress the non-relationship between contemporary Darwinian medicine and a research concept known as medical Darwinism that existed in the late nineteenth and early twentieth centuries. Medical Darwinism was a pseudoscientific framework that misapplied Darwinian evolutionary theory to support eugenicist ideas and efforts to explain observable differences in the physical characteristics and health outcomes of varying and often racialized population groups.
Topic Today
Evolutionary medicine experts often describe the discipline’s overarching objective as explaining how and why the process of natural selection continues to leave human beings prone to illness and disease. Researchers adopt multiple viewpoints in exploring related questions, some of which focus on exclusively human genetic and evolutionary factors, while others examine how the natural selection process impacts the various infectious agents and pathogens that cause disease. Examples of its areas of inquiry include questions as to how and why certain pathogenic bacteria develop resistance to antibiotics and why humans continue to carry and pass on genes that cause diseases.
Many questions in evolutionary medicine focus on identifying and proposing explanations rooted in evolutionary theory for certain features or processes of the human body. For instance, researchers have turned to evolutionary medicine in a bid to understand why the birth canal in adult females is so narrow, why the body has not eliminated the gene disorders that cause conditions like cystic fibrosis, and why obesity appears to have adopted genetic components. The varying ways in which researchers endeavor to answer these questions highlights the key difference between Darwinian and evolutionary medicine. Darwinian medicine looks exclusively at adaptive traits that promote higher rates of survival and reproduction, while evolutionary medicine considers both these traits as well as negative (maladaptive) traits that persist despite appearing to pose clear obstacles to evolutionary development.
Established areas of inquiry in evolutionary medicine include population genetics and pharmacogenomics. Population genetics is a subfield of biology that focuses exclusively on studying the genetic characteristics of specific population groups and tracking genetic changes over time. Researchers use mathematical modeling to map gene frequencies and predict the future courses of gene mutation and variation. It has been applied to various areas, including understanding conditions such as lactose intolerance, to determining how and why antibiotic resistance occurs. Pharmacogenomics is a specialized branch of genetics and evolutionary medicine that examines individual genetic characteristics in the context of how they affect a person’s response to specific pharmaceutical therapies.
Emerging areas of evolutionary medicine focus heavily on why human beings remain prone to diseases. Adopting a general framework that views the human body like a machine that has adapted over time for optimal function, evolutionary medicine researchers ask why the body retains specific features that leave it vulnerable to diseases, illnesses, and degenerative conditions. The various theories proposed by researchers include arguments that humans evolved to function in natural rather than urban environments, and humanity’s migration to unnatural environments is a causal factor in conditions ranging from obesity to substance abuse. Other hypotheses suggest that the answer lies within the evolutionary biology of disease-inducing pathogens, which must evolve themselves to evade both pharmaceutical agents and the human body’s natural defenses. Another idea holds that biological organisms are constantly subject to limitations and constraints that force certain concessions. For example, human bones could evolve to become thicker, stronger, and less prone to injury and disease, but this would elevate a person’s body weight to create mobility and agility trade-offs.
Evolutionary and Darwinian medicine also focus on many niche subtopics. Researchers explore questions related to human dietary culture and its impacts on both reproductive and general health, the evolutionary origins and development of both health and disease, aging and the upper limits of life extension efforts, degenerative diseases such as cancer and dementia, and the possible role of hygiene standards in the rising rates of allergy syndromes and autoimmune disorders seen in many high-income countries. Scientists also study the human microbiome, which describes the symbiotic relationship between human beings and the communities of microbial organisms that their bodies support, in the context of Darwinian medicine.
Evolutionary medicine has been credited with informing novel public health policies, particularly the implications of antibiotic-resistant pathogens. Its principles have also guided scientific efforts to identify previously unknown genes and gene mutations that cause diseases. The field is also actively incorporating climate change science into its modeling, recognizing it as a possible driver of future evolutionary change and adaptive advantage. Experts note that evolutionary medicine remains in its relative infancy, and the field could make critical contributions to the future of medicine, even though many of its inquiries and findings lack immediate practical applications.
Bibliography
Frenkel-Morgenstern, Milana and Solomon P. Wasser. New Horizons in Evolution. Elsevier Science, 2021.
“Investigating VIST Evolutionary Principles.” University of Kansas, 2014, biodiversity.ku.edu/sites/biodiversity/files/files/Investigating‗VIST‗Principles.pdf. Accessed 22 Mar. 2023.
Johnson, Norman A. Darwin’s Reach: 21st Century Applications of Evolutionary Biology. CRC Press, 2021.
Libertini, Giacinto, et. al. Evolutionary Gerontology and Geriatrics: How and Why We Age. Springer International Publishing, 2021.
Lucock, Mark D. “A Brief Introduction to Darwinian Medicine.” Exploratory Research and Hypothesis in Medicine, vol. 7, no. 2, 2022, pp. 108–124.
Natterson-Horowitz, B. "The Future of Evolutionary Medicine: Sparking Innovation in Biomedicine and Public Health." Frontiers in Science, vol. 1, 27 Feb. 2023, doi.org/10.3389/fsci.2023.997136. Accessed 13 Nov. 2024.
Nesse, Randolph M. “Ten Questions for Evolutionary Studies of Disease Vulnerability.” Evolutionary Applications, vol. 4, no. 2, Mar. 2011, pp. 264–277.
Okasha, Samir. “Population Genetics.” Stanford Encyclopedia of Philosophy, 24 Nov. 2022, plato.stanford.edu/entries/population-genetics/. Accessed 22 Mar. 2023.
Stearns, Stephen C. “Evolutionary Medicine: Its Scope, Interest, and Potential.” Proceedings of the Royal Society B, vol. 279, Aug. 2012, pp. 4305–4321.