Evolutionary medicine or Darwinian medicine is the application of modern

evolutionary theory Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

to understanding health and

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

. Modern biomedical research and practice have focused on the molecular and physiological mechanisms underlying health and disease, while evolutionary medicine focuses on the question of why evolution has shaped these mechanisms in ways that may leave us susceptible to disease. The evolutionary approach has driven important advances in the understanding of

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

autoimmune disease An autoimmune disease is a condition arising from an abnormal immune response to a functioning body part. At least 80 types of autoimmune diseases have been identified, with some evidence suggesting that there may be more than 100 types. Nearly a ...

, and

anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...

. Medical schools have been slower to integrate evolutionary approaches because of limitations on what can be added to existing medical curricula. Th
International Society for Evolution, Medicine and Public Health
coordinates efforts to develop the field. It owns the Oxford University Press journa
Evolution, Medicine and Public Health
an
The Evolution and Medicine Review

Core principles

Utilizing the

Delphi method } The Delphi method or Delphi technique ( ; also known as Estimate-Talk-Estimate or ETE) is a structured communication technique or method, originally developed as a systematic, interactive forecasting method which relies on a panel of experts. The ...

, 56 experts from a variety of disciplines, including anthropology, medicine, and biology agreed upon 14 core principles intrinsic to the education and practice of evolutionary medicine. These 14 principles can be further grouped into five general categories: question framing, evolution I and II (with II involving a higher level of complexity), evolutionary trade-offs, reasons for vulnerability, and culture. Additional information regarding these principles may be found in the table below.

Human adaptations

Adaptation works within constraints, makes compromises and trade-offs, and occurs in the context of different forms of competition.

Constraints

Adaptations can only occur if they are evolvable. Some adaptations which would prevent ill health are therefore not possible. * DNA cannot be totally prevented from undergoing somatic replication

corruption Corruption is a form of dishonesty or a criminal offense which is undertaken by a person or an organization which is entrusted in a position of authority, in order to acquire illicit benefits or abuse power for one's personal gain. Corruption m ...

; this has meant that

, which is caused by somatic mutations, has not (so far) been eliminated by natural selection. * Humans cannot biosynthesize

vitamin C Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) an ...

, and so risk

scurvy Scurvy is a disease resulting from a lack of vitamin C (ascorbic acid). Early symptoms of deficiency include weakness, feeling tired and sore arms and legs. Without treatment, decreased red blood cells, gum disease, changes to hair, and bleeding ...

, vitamin C deficiency disease, if dietary intake of the vitamin is insufficient. * Retinal neurons and their axon output have evolved to be inside the layer of retinal pigment cells. This creates a constraint on the evolution of the visual system such that the

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. In humans, the optic nerve i ...

is forced to exit the retina through a point called the

optic disc The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye. The ganglion cell axons form the ...

. This, in turn, creates a blind spot. More importantly, it makes vision vulnerable to increased pressure within the eye (

glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

) since this

cups CUPS (formerly an acronym for Common UNIX Printing System) is a modular computer printer, printing system for Unix-like computer operating systems which allows a computer to act as a print server. A computer running CUPS is a Server (computi ...

and damages the optic nerve at this point, resulting in impaired vision. Other constraints occur as the byproduct of adaptive innovations.

Trade-offs and conflicts

One constraint upon selection is that different adaptations can conflict, which requires a compromise between them to ensure an optimal cost-benefit tradeoff. * Running efficiency in women, and

birth canal In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen. ...

size *

Encephalization Encephalization quotient (EQ), encephalization level (EL), or just encephalization is a relative brain size measure that is defined as the ratio between observed to predicted brain mass for an animal of a given size, based on nonlinear regressi ...

, and gut size *

Skin pigmentation Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among individuals is caused by variation in pigmentation, which is the result of genetics (inherited from one's biological parents and or individu ...

protection Protection is any measure taken to guard a thing against damage caused by outside forces. Protection can be provided to physical objects, including organisms, to systems, and to intangible things like civil and political rights. Although th ...

from UV, and the skin synthesis of

vitamin D Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group are vitamin D3 (c ...

Speech Speech is a human vocal communication using language. Each language uses Phonetics, phonetic combinations of vowel and consonant sounds that form the sound of its words (that is, all English words sound different from all French words, even if ...

and its use of a descended larynx, and increased risk of

choking Choking, also known as foreign body airway obstruction (FBAO), is a phenomenon that occurs when breathing is impeded by a blockage inside of the respiratory tract. An obstruction that prevents oxygen from entering the lungs results in oxygen de ...

Competition effects

Different forms of competition exist and these can shape the processes of genetic change. *

mate choice Mate choice is one of the primary mechanisms under which evolution can occur. It is characterized by a "selective response by animals to particular stimuli" which can be observed as behavior.Bateson, Paul Patrick Gordon. "Mate Choice." Mate Choic ...

and disease susceptibility *

genomic conflict Intragenomic conflict refers to the evolutionary phenomenon where genes have phenotypic effects that promote their own transmission in detriment of the transmission of other genes that reside in the same genome. The selfish gene theory postulates ...

between mother and fetus that results in

pre-eclampsia Pre-eclampsia is a disorder of pregnancy characterized by the onset of high blood pressure and often a significant amount of protein in the urine. When it arises, the condition begins after 20 weeks of pregnancy. In severe cases of the disease ...

Lifestyle

Humans evolved to live as simple hunter-gatherers in small tribal bands, while contemporary humans have a more complex life. This change may make present-day humans susceptible to

lifestyle diseases Lifestyle diseases can be defined as diseases linked with one's lifestyle. These diseases are non-communicable diseases. They are caused by lack of physical activity , unhealthy eating, alcohol, substance use disorders and smoking tobacco, wh ...

Diet

In contrast to the diet of early hunter-gatherers, the modern

Western diet The Western pattern diet is a modern dietary pattern that is generally characterized by high intakes of pre-packaged foods, refined grains, red meat, processed meat, high-sugar drinks, candy and sweets, fried foods, conventionally-raised anim ...

often contains high quantities of fat, salt, and simple carbohydrates, such as refined sugars and flours. * Trans fat health risks *

Dental caries Tooth decay, also known as cavities or caries, is the breakdown of teeth due to acids produced by bacteria. The cavities may be a number of different colors from yellow to black. Symptoms may include pain and difficulty with eating. Complicatio ...

* High GI foods * Modern diet based on "common wisdom" regarding diets in the paleolithic era Among different countries, the incidence of

colon cancer Colorectal cancer (CRC), also known as bowel cancer, colon cancer, or rectal cancer, is the development of cancer from the colon or rectum (parts of the large intestine). Signs and symptoms may include blood in the stool, a change in bowel mo ...

varies widely, and the extent of exposure to a

Western pattern diet The Western pattern diet is a modern dietary pattern that is generally characterized by high intakes of pre-packaged foods, refined grains, red meat, processed meat, high-sugar drinks, candy and sweets, fried foods, conventionally-raised ani ...

may be a factor in cancer incidence.

Life expectancy

Examples of aging-associated diseases are

atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis in which the wall of the artery develops abnormalities, called lesions. These lesions may lead to narrowing due to the buildup of atheroma, atheromatous plaque. At onset there are usu ...

and

cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, h ...

arthritis Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In som ...

cataracts A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble w ...

osteoporosis Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone fragility, and consequent increase in fracture risk. It is the most common reason for a broken bone ...

, type 2 diabetes,

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

and

Alzheimer's disease Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...

. The incidence of all of these diseases increases rapidly with

aging Ageing ( BE) or aging ( AE) is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In ...

(increases

exponentially Exponential may refer to any of several mathematical topics related to exponentiation, including: *Exponential function, also: **Matrix exponential, the matrix analogue to the above * Exponential decay, decrease at a rate proportional to value *Exp ...

with age, in the case of cancer). Age Specific SEER Incidence Rates 2003-2007

Of the roughly 150,000 people who die each day across the globe, about two thirds—100,000 per day—die of age-related causes. In industrialized nations, the proportion is much higher, reaching 90%.

Exercise

Many contemporary humans engage in little

physical exercise Exercise is a body activity that enhances or maintains physical fitness and overall health and wellness. It is performed for various reasons, to aid growth and improve strength, develop muscles and the cardiovascular system, hone athletic ...

compared to the physically active lifestyles of ancestral

hunter-gatherer A traditional hunter-gatherer or forager is a human living an ancestrally derived lifestyle in which most or all food is obtained by foraging, that is, by gathering food from local sources, especially edible wild plants but also insects, fungi, ...

s. Prolonged periods of inactivity may have only occurred in early humans following illness or injury, so a modern sedentary lifestyle may continuously cue the body to trigger life preserving metabolic and stress-related responses such as

inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...

, and some theorize that this causes chronic diseases.

Cleanliness

Contemporary humans in developed countries are mostly free of

parasites Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...

, particularly intestinal ones. This is largely due to frequent washing of clothing and the body, and improved sanitation. Although such hygiene can be very important when it comes to maintaining good health, it can be problematic for the proper development of the immune system. The hygiene hypothesis is that humans evolved to be dependent on certain microorganisms that help establish the immune system, and modern hygiene practices can prevent necessary exposure to these microorganisms. "Microorganisms and macroorganisms such as helminths from mud, animals, and feces play a critical role in driving immunoregulation" (Rook, 2012). Essential microorganisms play a crucial role in building and training immune functions that fight off and repel some diseases, and protect against excessive inflammation, which has been implicated in several diseases. For instance, recent studies have found evidence supporting inflammation as a contributing factor in Alzheimer's Disease.

Specific explanations

This is a partial list: all links here go to a section describing or debating its evolutionary origin.

Life stage related

Adipose tissue Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular e ...

in human infants *

Arthritis Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In som ...

and other chronic inflammatory diseasesStraub, R. H., del Rey, A., Besedovsky, H. O. (2007) "Emerging concepts for the pathogenesis of chronic disabling inflammatory diseases: neuroendocrine-immune interactions and evolutionary biology" In: Ader, R. (2007) "Psychoneuroimmunology", Volume 1, Academic Press, San Diego, pp.217-232 *

Ageing Ageing ( BE) or aging ( AE) is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In ...

* Alzheimer disease * Childhood *

Menarche Menarche ( ; ) is the first menstrual cycle, or first menstrual bleeding, in female humans. From both social and medical perspectives, it is often considered the central event of female puberty, as it signals the possibility of fertility. Gir ...

Menopause Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often d ...

Menstruation Menstruation (also known as a period, among other colloquial terms) is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. The menstrual cycle is characterized by the rise and fall of hor ...

Morning sickness Morning sickness, also called nausea and vomiting of pregnancy (NVP), is a symptom of pregnancy that involves nausea or vomiting. Despite the name, nausea or vomiting can occur at any time during the day. Typically the symptoms occur between th ...

Other

* Atherosclerosis *

and other chronic inflammatory diseases *Cough] * Cystic fibrosis#Evolution, Cystic fibrosis * Dental occlusion * Diabetes Type II *

Diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

* Essential hypertension * Fever *

Gestational hypertension Gestational hypertension or pregnancy-induced hypertension (PIH) is the development of new hypertension in a pregnant woman after 20 weeks' gestation without the presence of protein in the urine or other signs of pre-eclampsia. Gestational hyperte ...

* Gout *

Iron deficiency Iron deficiency, or sideropenia, is the state in which a body lacks enough iron to supply its needs. Iron is present in all cells in the human body and has several vital functions, such as carrying oxygen to the tissues from the lungs as a key ...

(paradoxical benefits) *

Obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...

* Phenylketonuria *

Placebos A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures. In general, placebos can af ...

* Osteoporosis * Red blood cell polymorphism disorders *

Sickle cell anemia Sickle cell disease (SCD) is a group of blood disorders typically inherited from a person's parents. The most common type is known as sickle cell anaemia. It results in an abnormality in the oxygen-carrying protein haemoglobin found in red blo ...

Sickness behavior 350px, Ancher, Michael, "The Sick Girl", 1882, Statens Museum for Kunst Sickness behavior is a coordinated set of adaptive behavioral changes that develop in ill individuals during the course of an infection. They usually, but not always, accom ...

* Women's reproductive cancers

Evolutionary psychology

As noted in the table below, adaptationist hypotheses regarding the etiology of psychological disorders are often based on analogies with evolutionary perspectives on medicine and physiological dysfunctions (see in particular, Randy Nesse and George C. Williams' book ''Why We Get Sick''). Evolutionary psychiatrists and psychologists suggest that some mental disorders likely have multiple causes.Gaulin, Steven J. C. and Donald H. McBurney. Evolutionary psychology. Prentice Hall. 2003. , Chapter 1, p 1-24. See several topic areas, and the associated references, below. * Agoraphobia * Anxiety * Depression * Drug abuse *

Schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social withdra ...

* Unhappiness

History

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...

did not discuss the implications of his work for medicine, though

biologist A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual Cell (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...

s quickly appreciated the

germ theory of disease The germ theory of disease is the currently accepted scientific theory for many diseases. It states that microorganisms known as pathogens or "germs" can lead to disease. These small organisms, too small to be seen without magnification, invade h ...

and its implications for understanding the evolution of

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

s, as well as an organism's need to defend against them. Medicine, in turn, ignored evolution, and instead focused (as done in the

hard science Hard science and soft science are colloquial terms used to compare scientific fields on the basis of perceived methodological rigor, exactitude, and objectivity. Roughly speaking, the formal sciences & natural sciences are considered "hard", wher ...

s) upon proximate mechanical causes. George C. Williams was the first to apply evolutionary theory to health in the context of

senescence Senescence () or biological aging is the gradual deterioration of functional characteristics in living organisms. The word ''senescence'' can refer to either cellular senescence or to senescence of the whole organism. Organismal senescence inv ...

.
abstract
/ref> Also in the 1950s,

John Bowlby Edward John Mostyn Bowlby, CBE, FBA, FRCP, FRCPsych (; 26 February 1907 – 2 September 1990) was a British psychologist, psychiatrist, and psychoanalyst, notable for his interest in child development and for his pioneering work in attachmen ...

approached the problem of disturbed child development from an evolutionary perspective upon attachment. An important theoretical development was Nikolaas Tinbergen's distinction made originally in

ethology Ethology is the scientific study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait. Behaviourism as a term also describes the scientific and objectiv ...

between evolutionary and proximate mechanisms.

Randolph M. Nesse Randolph M. Nesse (born 1948) is an American physician, scientist and author who is notable for his role as a founder of the field of evolutionary medicine and evolutionary psychiatry. He is professor of life sciences and ASU Foundation Professo ...

summarizes its relevance to medicine: The paper of Paul Ewald in 1980, "Evolutionary Biology and the Treatment of Signs and Symptoms of Infectious Disease", and that of Williams and Nesse in 1991, "The Dawn of Darwinian Medicine" were key developments. The latter paper "draw a favorable reception",^{page x} and led to a book, ''Why We Get Sick'' (published as ''Evolution and healing'' in the UK). In 2008, an online journal started
Evolution and Medicine Review

References

External links

Evolution and Medicine Network

Special Issue of Evolutionary Applications on Evolutionary Medicine
{{DEFAULTSORT:Evolutionary Medicine Evolutionary biology Clinical medicine