Evolutionary medicine and bioastronautics: an innovative approach in addressing adverse mental health effects to astronauts during long term space missions

Although evolutionary medicine has produced several novel insights for explaining prevalent health issues, it has yet to sufficiently address possible adverse mental health effects of humans during long-term space missions While evolutionary applications to medicine have increased over the past 20 years, there is scope for the integration of evolutionary applications in the new branch of space medicine called bioastronautics, which analyses the effects on human bodies when in outer space. Evolutionary principles may explain what kinds of space environments increase mental health risks to astronauts, both in the short and long term; secondly, evolutionary principles may provide a more informed understanding of the evolutionary mismatch between terrestrial and space environments in which astronauts exist. This information may assist in developing frameworks for improving mental health of astronauts and future space colonists. Consequently, this paper will focus on some of the major evolutionary mismatches currently confronting astronauts' mental health, with an aim to improve medical knowledge. It will also provide possible therapeutic countermeasures based on evolutionary principles for reducing adverse mental effects on astronauts.

Integrating microbiome science and evolutionary medicine into animal health and conservation

Microbiome science has provided groundbreaking insights into human and animal health. Similarly, evolutionary medicine - the incorporation of eco-evolutionary concepts into primarily human medical theory and practice - is increasingly recognised for its novel perspectives on modern diseases. Studies of host-microbe relationships have been expanded beyond humans to include a wide range of animal taxa, adding new facets to our understanding of animal ecology, evolution, behaviour, and health. In this review, we propose that a broader application of evolutionary medicine, combined with microbiome science, can provide valuable and innovative perspectives on animal care and conservation. First, we draw on classic ecological principles, such as alternative stable states, to propose an eco-evolutionary framework for understanding variation in animal microbiomes and their role in animal health and wellbeing. With a focus on mammalian gut microbiomes, we apply this framework to populations of animals under human care, with particular relevance to the many animal species that suffer diseases linked to gut microbial dysfunction (e.g. gut distress and infection, autoimmune disorders, obesity). We discuss diet and microbial landscapes (i.e. the microbes in the animal's external environment), as two factors that are (i) proposed to represent evolutionary mismatches for captive animals, (ii) linked to gut microbiome structure and function, and (iii) potentially best understood from an evolutionary medicine perspective. Keeping within our evolutionary framework, we highlight the potential benefits - and pitfalls - of modern microbial therapies, such as pre- and probiotics, faecal microbiota transplants, and microbial rewilding. We discuss the limited, yet growing, empirical evidence for the use of microbial therapies to modulate animal gut microbiomes beneficially. Interspersed throughout, we propose 12 actionable steps, grounded in evolutionary medicine, that can be applied to practical animal care and management. We encourage that these actionable steps be paired with integration of eco-evolutionary perspectives into our definitions of appropriate animal care standards. The evolutionary perspectives proposed herein may be best appreciated when applied to the broad diversity of species under human care, rather than when solely focused on humans. We urge animal care professionals, veterinarians, nutritionists, scientists, and others to collaborate on these efforts, allowing for simultaneous care of animal patients and the generation of valuable empirical data.

Evolutionary medicine approaches to chronic disease: The case of irritable bowel syndrome

Irritable bowel syndrome (IBS), a gastrointestinal disease, is a global phenomenon correlated with industrialization. We propose that an evolutionary medicine approach is useful to understand this disease from an ultimate perspective and conducted a scoping literature review to synthesize the IBS literature within this framework. Our review suggests five potential evolutionary hypotheses for the cause of IBS, including (a) a dietary mismatch accompanying a nutritional transition, (b) an early hygienic life environment leading to the immune system and microbiotic changes, (c) an outcome of decreased physical activity, (d) a response to changes in environmental light-dark cycles, and (e) an artifact of an evolved fight or flight response. We find key limitations in the available data needed to understand early life, nutritional, and socioeconomic experiences that would allow us to understand evolutionarily relevant risk factors and identify a need for further empirical research to distinguish potential causes and test evolutionary hypotheses.

Evolutionary psychiatry: foundations, progress and challenges

Evolutionary biology provides a crucial foundation for medicine and behavioral science that has been missing from psychiatry. Its absence helps to explain slow progress; its advent promises major advances. Instead of offering a new kind of treatment, evolutionary psychiatry provides a scientific foundation useful for all kinds of treatment. It expands the search for causes from mechanistic explanations for disease in some individuals to evolutionary explanations for traits that make all members of a species vulnerable to disease. For instance, capacities for symptoms such as pain, cough, anxiety and low mood are universal because they are useful in certain situations. Failing to recognize the utility of anxiety and low mood is at the root of many problems in psychiatry. Determining if an emotion is normal and if it is useful requires understanding an individual's life situation. Conducting a review of social systems, parallel to the review of systems in the rest of medicine, can help achieve that understanding. Coping with substance abuse is advanced by acknowledging how substances available in modern environments hijack chemically mediated learning mechanisms. Understanding why eating spirals out of control in modern environments is aided by recognizing the motivations for caloric restriction and how it arouses famine protection mechanisms that induce binge eating. Finally, explaining the persistence of alleles that cause serious mental disorders requires evolutionary explanations of why some systems are intrinsically vulnerable to failure. The thrill of finding functions for apparent diseases is evolutionary psychiatry's greatest strength and weakness. Recognizing bad feelings as evolved adaptations corrects psychiatry's pervasive mistake of viewing all symptoms as if they were disease manifestations. However, viewing diseases such as panic disorder, melancholia and schizophrenia as if they are adaptations is an equally serious mistake in evolutionary psychiatry. Progress will come from framing and testing specific hypotheses about why natural selection left us vulnerable to mental disorders. The efforts of many people over many years will be needed before we will know if evolutionary biology can provide a new paradigm for understanding and treating mental disorders.

How and why we should move beyond natural selection in museums to tackle teleology

Background

Museum displays commonly use a "VIST" approach (Variation, Inheritance, Selection, and Time) to explain evolution to visitors. I contend that this framework, by focusing narrowly on natural selection, unintentionally reinforces intuitive teleological thinking and a "survival of the fittest" mentality. Exhibits that incorporate all the forces (or mechanisms) of evolution will instead challenge visitors' preconceptions and enable them to develop a deeper understanding of evolution. In particular, visitors will appreciate that evolution is not progressive, with modern humans as the "most evolved" species.

Results

Explicit and implicit description of the forces of evolution is surveyed in 12 museums: 4 in Texas, 7 elsewhere in the U.S., and the Natural History Museum in London. Museum exhibits focus primarily on natural selection (explicit in 10 of 12) and often mention mutation (explicit in 7). Only the American Museum of Natural History in New York, in my sample, provides an explicit explanation of genetic drift.

Conclusions

Heavy emphasis on natural selection and limited explanation of stochastic forces contributes to an impoverished view of evolution. Exhibits should more effectively convey the complexity of microevolution. Computer simulations showing the interactions of evolutionary forces can accomplish this goal.

Sound reasons for unsound sleep: Comparative support for the sentinel hypothesis in industrial and nonindustrial groups

Background and objectives

Sleep is a vulnerable state in which individuals are more susceptible to threat, which may have led to evolved mechanisms for increasing safety. The sentinel hypothesis proposes that brief awakenings during sleep may be a strategy for detecting and responding to environmental threats. Observations of sleep segmentation and group sentinelization in hunter-gatherer and small-scale communities support this hypothesis, but to date it has not been tested in comparisons with industrial populations characterized by more secure sleep environments.

Methodology

Here, we compare wake after sleep onset (WASO), a quantitative measure of nighttime awakenings, between two nonindustrial and two industrial populations: Hadza hunter-gatherers (n = 33), Malagasy small-scale agriculturalists (n = 38), and Hispanic (n = 1,531) and non-Hispanic White (NHW) (n = 347) Americans. We compared nighttime awakenings between these groups using actigraphically-measured sleep data. We fit linear models to assess whether WASO varies across groups, controlling for sex and age.

Results

We found that WASO varies significantly by group membership and is highest in Hadza (2.44 h) and Malagasy (1.93 h) and lowest in non-Hispanic Whites (0.69 h). Hispanics demonstrate intermediate WASO (0.86 h), which is significantly more than NHW participants. After performing supplementary analysis within the Hispanic sample, we found that WASO is significantly and positively associated with increased perception of neighborhood violence.

Conclusions and implications

Consistent with principles central to evolutionary medicine, we propose that evolved mechanisms to increase vigilance during sleep may now be mismatched with relatively safer environments, and in part responsible for driving poor sleep health.

What is normal bone health? A bioarchaeological perspective on meaningful measures and interpretations of bone strength, loss, and aging

Bioarchaeological (the study of archeological human remains together with contextual and documentary evidence) offers a unique vantage point to examine variation in skeletal morphology related to influences such as activity, disease, and nutrition. The human skeleton is composed of a dynamic tissue that is forged by biocultural factors over the entire life course, providing a record of individual, and community history. Various aspects of adult bone health, particularly bone maintenance and loss and the associated skeletal disease osteoporosis, have been examined in numerous past populations. The anthropological study of bone loss has traditionally focused on the signature of postmenopausal aging, costs of reproduction, and fragility in females. The a priori expectation of normative sex-related bone loss/fragility in bioanthropological studies illustrates the wider gender-ideological bias that continues in research design and data analysis in the field. Contextualized data on bone maintenance and aging in the archeological record show that patterns of bone loss do not constitute predictable consequences of aging or biological sex. Instead, the critical examination of bioarchaeological data highlights the complex and changing processes that craft the human body over the life course, and calls for us to question the ideal or "normal" range of bone quantity and quality in the human skeleton, and to critically reflect on what measures are actually biologically and/or socially meaningful.

Encouraging Cross-Disciplinary Collaboration and Innovation in Epidemiology in Japan

Background: Scientific innovation is often achieved through the intersection of ideas from different fields. However, barriers prevent non-epidemiologists from cultivating interests in epidemiology or undertaking epidemiologic work. In this study, we evaluated changes in the diversity of research topics in an epidemiologic journal over time. We aimed to understand how epidemiologists and non-epidemiologists communicate about epidemiologic data and how this impacts innovation in the field. Methods: We categorized the topics of articles published in the Journal of Epidemiology during the early and late 2010s based on their titles. We calculated the Shannon-Weaver diversity index (H') to measure changes in the diversity of topics addressed by published articles. Results: Comparing 2011-2013 with 2017-2019, there was no significant change in the diversity of article topics (H' = 4.25 and 4.21, respectively) published in the Journal of Epidemiology. Conclusion: To encourage healthcare providers and public administrators to conduct or comment on epidemiologic studies, epidemiologists should present their findings in easily understood language with appropriate and relevant statistical indicators and useful illustrations. Bringing experience from other specialties into epidemiology may yield new findings from epidemiologic data because of the exposure of non-epidemiologists to different values, workplaces, and occupations. Collaboration among professionals from varied backgrounds and with varied occupational experiences may help to promote scientific innovation by broadening perspectives. In addition, a range of professional experiences may enable individuals to solve difficult research questions more easily by themselves.

Out of balance: the role of evolutionary mismatches in the sex disparity in autoimmune disease

Over the past century autoimmune disease incidence has increased rapidly in (post-) industrialised, affluent societies, suggesting that changes in ecology and lifestyle are driving this development. Epidemiological studies show that (i) 80% of autoimmune disease patients are female, (ii) autoimmune diseases co-occur more often in women, and (iii) the incidence of some autoimmune diseases is increasing faster in women than in men. The female preponderance in autoimmunity is most pronounced between puberty and menopause, suggesting that diverging sex hormone levels during the reproductive years are implicated in autoimmune disease development. Using an evolutionary perspective, we build on the hypotheses that female immunity is cyclical in menstruating species and that natural selection shaped the female immune system to optimise the implantation and gestation of a semi-allogeneic foetus. We propose that cyclical immunomodulation and female immune tolerance mechanisms are currently out of balance because of a mismatch between the conditions under which they evolved and (post-)industrialised, affluent lifestyles. We suggest that current changes in autoimmune disease prevalence may be caused by increases in lifetime exposure to cyclical immunomodulation and ovarian hormone exposure, reduced immune challenges, increased reproductive lifespan, changed reproductive patterns, and enhanced positive energy balance associated with (post-)industrialised, affluent lifestyles. We discuss proximate mechanisms by which oestrogen and progesterone influence tolerance induction and immunomodulation, and review the effect of the menstrual cycle, pregnancy, and contraceptive use on autoimmune disease incidence and symptoms.

Can ancient and modern stressors be distinguished? A mixed-methods exploration of psychosocial characteristics and health symptoms in young and older adults

A novel conceptualisation of stress includes a distinction between ancient (AS) and modern stressors (MS); the notion that established adaptive psychophysiological coping processes may enable individuals to better withstand AS than MS. Two consecutive mixed-methods studies assessed the feasibility of distinguishing between AS and MS in young and older adults, using questionnaires and interviews. MS were positively associated with cold symptoms in older adults; and five psychosocial characteristics were identified to profile AS and MS along a continuum. An evolutionary distinction between AS and MS provides an important psychological dimension in better understanding and assessing stress-health processes.

Mental health is biological health: Why tackling "diseases of the mind" is an imperative for biological anthropology in the 21st century

The germ theory of disease and the attendant public health initiatives, including sanitation, vaccination, and antibiotic treatment, led to dramatic increases in global life expectancy. As the prevalence of infectious disease declines, mental disorders are emerging as major contributors to the global burden of disease. Scientists understand little about the etiology of mental disorders, however, and many of the most popular psychopharmacological treatments, such as antidepressants and antipsychotics, have only moderate-to-weak efficacy in treating symptoms and fail to target biological systems that correspond to discrete psychiatric syndromes. Consequently, despite dramatic increases in the treatment of some mental disorders, there has been no decrease in the prevalence of most mental disorders since accurate record keeping began. Many researchers and theorists are therefore endeavoring to rethink psychiatry from the ground-up. Anthropology, especially biological anthropology, can offer critical theoretical and empirical insights to combat mental illness globally. Biological anthropologists are unique in that we take a panhuman approach to human health and behavior and are trained to address each of Tinbergen's four levels of analysis as well as culture. The field is thus exceptionally well-situated to help resolve the mysteries of mental illness by integrating biological, evolutionary, and sociocultural perspectives.

Adhesive capsulitis: An age related symptom of metabolic syndrome and chronic low-grade inflammation?

Adhesive capsulitis (AC) is very poorly understood, particularly it's underlying etiology. Obesity and metabolic syndrome, which are strongly associated with chronic low grade inflammation, are becoming increasingly understood to underlie a raft of morbid states including upper limb pain syndromes, diabetes (DM), cardiovascular disease (CVD), cancer and central nervous system dysfunction and degeneration. Notwithstanding age, two of the strongest established risk factors for AC are DM and CVD. The hypothesis argues that similar to DM and CVD, the inflammation and capsular fibrosis seen in AC is precipitated by metabolic syndrome and chronic low grade inflammation. These pathophysiological mechanisms are highly likely to be perpetuated by upregulation of pro-inflammatory cytokine production, sympathetic dominance of autonomic balance, and neuro-immune activation. The hypothesis predicts and describes how these processes may etiologically underpin and induce each sub-classification of AC. An improved understanding of the etiology of AC may lead to more accurate diagnosis, improved management, treatment outcomes, and reduce or prevent pain, disability and suffering associated with the disease. The paper follows on with a discussion of similarities between the pathophysiology of AC to general systemic inflammatory control mechanisms whereby connective tissue (CT) fibrosis is induced as a storage depot for leukocytes and chronic inflammatory cells. The potential role of hyaluronic acid (HA), the primary component of the extracellular matrix (ECM) and CT, in the pathophysiology of AC is also discussed with potential treatment implications. Lastly, a biochemical link between physical and mental health through the ECM is described and the concept of a periventricular-limbic central driver of CT dysfunction is introduced.

The ancestral shape hypothesis: an evolutionary explanation for the occurrence of intervertebral disc herniation in humans

Background

Recent studies suggest there is a relationship between intervertebral disc herniation and vertebral shape. The nature of this relationship is unclear, however. Humans are more commonly afflicted with spinal disease than are non-human primates and one suggested explanation for this is the stress placed on the spine by bipedalism. With this in mind, we carried out a study of human, chimpanzee, and orangutan vertebrae to examine the links between vertebral shape, locomotion, and Schmorl’s nodes, which are bony indicators of vertical intervertebral disc herniation. We tested the hypothesis that vertical disc herniation preferentially affects individuals with vertebrae that are towards the ancestral end of the range of shape variation within Homo sapiens and therefore are less well adapted for bipedalism.

Results

The study employed geometric morphometric techniques. Two-dimensional landmarks were used to capture the shapes of the superior aspect of the body and posterior elements of the last thoracic and first lumbar vertebrae of chimpanzees, orangutans, and humans with and without Schmorl’s nodes. These data were subjected to multivariate statistical analyses.

Canonical Variates Analysis indicated that the last thoracic and first lumbar vertebrae of healthy humans, chimpanzees, and orangutans can be distinguished from each other (p<0.028), but vertebrae of pathological humans and chimpanzees cannot (p>0.4590). The Procrustes distance between pathological humans and chimpanzees was found to be smaller than the one between pathological and healthy humans. This was the case for both vertebrae. Pair-wise MANOVAs of Principal Component scores for both the thoracic and lumbar vertebrae found significant differences between all pairs of taxa (p<0.029), except pathological humans vs chimpanzees (p>0.367). Together, these results suggest that human vertebrae with Schmorl’s nodes are closer in shape to chimpanzee vertebrae than are healthy human vertebrae.

Conclusions

The results support the hypothesis that intervertebral disc herniation preferentially affects individuals with vertebrae that are towards the ancestral end of the range of shape variation within H. sapiens and therefore are less well adapted for bipedalism. This finding not only has clinical implications but also illustrates the benefits of bringing the tools of evolutionary biology to bear on problems in medicine and public health.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-015-0336-y) contains supplementary material, which is available to authorized users.

Public health evolutionary biology of antimicrobial resistance: priorities for intervention

The three main processes shaping the evolutionary ecology of antibiotic resistance (AbR) involve the emergence, invasion and occupation by antibiotic-resistant genes of significant environments for human health. The process of emergence in complex bacterial populations is a high-frequency, continuous swarming of ephemeral combinatory genetic and epigenetic explorations inside cells and among cells, populations and communities, expanding in different environments (migration), creating the stochastic variation required for evolutionary progress. Invasion refers to the process by which AbR significantly increases in frequency in a given (invaded) environment, led by external invaders local multiplication and spread, or by endogenous conversion. Conversion occurs because of the spread of AbR genes from an exogenous resistant clone into an established (endogenous) bacterial clone(s) colonizing the environment; and/or because of dissemination of particular resistant genetic variants that emerged within an endogenous clonal population. Occupation of a given environment by a resistant variant means a permanent establishment of this organism in this environment, even in the absence of antibiotic selection. Specific interventions on emergence influence invasion, those acting on invasion also influence occupation and interventions on occupation determine emergence. Such interventions should be simultaneously applied, as they are not simple solutions to the complex problem of AbR.

Evolutionary medicine and its implications for endocrinological issues (e.g. menopause)

Evolutionary medicine, which was formalized in the early 1990s, investigates evolutionary causes of recent human disease, disorders and malfunctions but also the influence of changing living conditions and modernization on health and disease. Evolutionary medicine can also provide insights into endocrinological disorders and in particular in the process of female reproductive senescence. Female reproductive senescence, i.e. menopausal transition is physiologically caused by the decline of estrogen secretion, which is associated with various somatic and psychic discomforts making this stage of life extremely uncomfortable. From the viewpoint of evolutionary medicine, these menopausal symptoms are the result from the sudden decrease of very high lifetime estrogen levels to zero during postmenopause, a situation which is quite new in our evolution and history. While women in recent developed countries experience menarche early, menopause late, few pregnancies, short periods of lactation and consequently low life time estrogen levels. The opposite is true of women living in traditional societies, whose living conditions may be interpreted as a mirror of the situation in our history. From this viewpoint we can conclude that menopausal symptoms may are the result of a mismatch between female reproductive physiology and recent living conditions.

Islamic medicine and evolutionary medicine: a comparative analysis

The advent of evolutionary medicine in the last two decades has provided new insights into the causes of human disease and possible preventative strategies. One of the strengths of evolutionary medicine is that it follows a multi-disciplinary approach. Such an approach is vital to future biomedicine as it enables for the infiltration of new ideas. Although evolutionary medicine uses Darwinian evolution as a heuristic for understanding human beings' susceptibility to disease, this is not necessarily in conflict with Islamic medicine. It should be noted that current evolutionary theory was first expounded by various Muslim scientists such as al-Jāḥiẓ, al-Ṭūsī, Ibn Khaldūn and Ibn Maskawayh centuries before Darwin and Wallace. In this way, evolution should not be viewed as being totally antithetical to Islam. This article provides a comparative overview of Islamic medicine and Evolutionary medicine as well as drawing points of comparison between the two approaches which enables their possible future integration.

Menopause, A Biocultural Perspective

Each menopausal body is the product of decades of physiological responses to an environment composed of cultural and biological factors. Anthropologists have documented population differences in reproductive endocrinology and developmental trajectories, and ethnic differences in hormones and symptoms at menopause demonstrate that this stage of life history is not exempt from this pattern. Antagonistic pleiotropy, in the form of constraints on the reproductive system, may explain the phenomenon of menopause in humans, optimizing the hormonal environment for reproduction earlier in the life course. Some menopausal symptoms may be side effects of modernizing lifestyle changes, representing discordance between our current lifestyles and genetic heritage. Further exploration of women's experience of menopause, as opposed to researcher-imposed definitions; macro- and microenvironmental factors, including diet and intestinal ecology; and folk etiologies involving the autonomic nervous system may lead to a deeper understanding of the complex biocultural mechanisms of menopause.

Conceptualizing the autism spectrum in terms of natural selection and behavioral ecology: the solitary forager hypothesis

This article reviews etiological and comparative evidence supporting the hypothesis that some genes associated with the autism spectrum were naturally selected and represent the adaptive benefits of being cognitively suited for solitary foraging. People on the autism spectrum are conceptualized here as ecologically competent individuals that could have been adept at learning and implementing hunting and gathering skills in the ancestral environment. Upon independence from their mothers, individuals on the autism spectrum may have been psychologically predisposed toward a different life-history strategy, common among mammals and even some primates, to hunt and gather primarily on their own. Many of the behavioral and cognitive tendencies that autistic individuals exhibit are viewed here as adaptations that would have complemented a solitary lifestyle. For example, the obsessive, repetitive and systemizing tendencies in autism, which can be mistakenly applied toward activities such as block stacking today, may have been focused by hunger and thirst toward successful food procurement in the ancestral past. Both solitary mammals and autistic individuals are low on measures of gregariousness, socialization, direct gazing, eye contact, facial expression, facial recognition, emotional engagement, affiliative need and other social behaviors. The evolution of the neurological tendencies in solitary species that predispose them toward being introverted and reclusive may hold important clues for the evolution of the autism spectrum and the natural selection of autism genes. Solitary animals are thought to eschew unnecessary social contact as part of a foraging strategy often due to scarcity and wide dispersal of food in their native environments. It is thought that the human ancestral environment was often nutritionally sparse as well, and this may have driven human parties to periodically disband. Inconsistencies in group size must have led to inconsistencies in the manner in which natural selection fashioned the social minds of humans, which in turn may well be responsible for the large variation in social abilities seen in human populations. This article emphasizes that individuals on the autism spectrum may have only been partially solitary, that natural selection may have only favored subclinical autistic traits and that the most severe cases of autism may be due to assortative mating.

An evolutionary review of human telomere biology: the thrifty telomere hypothesis and notes on potential adaptive paternal effects

Telomeres, repetitive DNA sequences found at the ends of linear chromosomes, play a role in regulating cellular proliferation, and shorten with increasing age in proliferating human tissues. The rate of age-related shortening of telomeres is highest early in life and decreases with age. Shortened telomeres are thought to limit the proliferation of cells and are associated with increased morbidity and mortality. Although natural selection is widely assumed to operate against long telomeres because they entail increased cancer risk, the evidence for this is mixed. Instead, here it is proposed that telomere length is primarily limited by energetic constraints. Cell proliferation is energetically expensive, so shorter telomeres should lead to a thrifty phenotype. Shorter telomeres are proposed to restrain adaptive immunity as an energy saving mechanism. Such a limited immune system, however, might also result in chronic infections, inflammatory stress, premature aging, and death--a more "disposable soma." With an increased reproductive lifespan, the fitness costs of premature aging are higher and longer telomeres will be favored by selection. Telomeres exhibit a paternal effect whereby the offspring of older fathers have longer telomeres due to increased telomere lengths of sperm with age. This paternal effect is proposed to be an adaptive signal of the expected age of male reproduction in the environment offspring are born into. The offspring of lineages of older fathers will tend to have longer, and thereby less thrifty, telomeres, better preparing them for an environment with higher expected ages at reproduction.

Evolution in health and medicine Sackler colloquium: Making evolutionary biology a basic science for medicine

New applications of evolutionary biology in medicine are being discovered at an accelerating rate, but few physicians have sufficient educational background to use them fully. This article summarizes suggestions from several groups that have considered how evolutionary biology can be useful in medicine, what physicians should learn about it, and when and how they should learn it. Our general conclusion is that evolutionary biology is a crucial basic science for medicine. In addition to looking at established evolutionary methods and topics, such as population genetics and pathogen evolution, we highlight questions about why natural selection leaves bodies vulnerable to disease. Knowledge about evolution provides physicians with an integrative framework that links otherwise disparate bits of knowledge. It replaces the prevalent view of bodies as machines with a biological view of bodies shaped by evolutionary processes. Like other basic sciences, evolutionary biology needs to be taught both before and during medical school. Most introductory biology courses are insufficient to establish competency in evolutionary biology. Premedical students need evolution courses, possibly ones that emphasize medically relevant aspects. In medical school, evolutionary biology should be taught as one of the basic medical sciences. This will require a course that reviews basic principles and specific medical applications, followed by an integrated presentation of evolutionary aspects that apply to each disease and organ system. Evolutionary biology is not just another topic vying for inclusion in the curriculum; it is an essential foundation for a biological understanding of health and disease.

Medicine, evolution, and natural selection: an historical overview

Contemporary Darwinian medicine is a still-expanding new discipline, one of whose principal aims is to arrive at an evolutionary understanding of those aspects of the body that leave it vulnerable to disease. Historically, there was a precedent for this research; between 1880 and 1940, several scientists tried to develop some general evolutionary theories of disease as arising from deleterious traits that escape elimination by natural selection. In contrast, contemporary Darwinian medicine uses evolutionary theory to consider all the possible reasons why selection has left humans vulnerable to disease.

Reconsidering the placebo response from a broad anthropological perspective

This paper considers how the full range of human experience may catalyze a placebo response. The placebo effect has been characterized as something to control in clinical research, something to cultivate in clinical practice and something present in all healing encounters. We examine domains in which the term 'placebo' is used in discourse: clinical research, clinical practice, media representations of treatment efficacy and lay interpretations of placebo--an underresearched topic. We briefly review major theoretical frameworks proposed to explain the placebo effect: classical conditioning, expectancy, the therapeutic relationship and sociocultural 'meaning.' As a corrective to what we see as an overemphasis on conscious cognitive approaches to understanding placebo, we reorient the discussion to argue that direct embodied experience may take precedence over meaning-making in the healing encounter. As an example, we examine the neurobiology of rehearsing or visualizing wellness as a mode of directly (performatively) producing an outcome often dismissed as a 'placebo response.' Given body/mind/emotional resonance, we suggest that the placebo response is an evolutionarily adaptive trait and part of healing mechanisms operating across many levels--from genetic and cellular to social and cultural.

Evolutionary Medicine: A Powerful Tool for Improving Human Health

Modern evolutionary research has much to contribute to medical research and health care practices. Conversely, evolutionary biologists are tapping into the rapidly expanding databases of medical genomic information to further their research. These two fields, which have historically functioned in almost complete isolation, are finding mutual benefit in the exchange of information. The long-term benefits of this synthesis of two major areas of research include improved health care. Recently, efforts to catalyze this relationship have brought together evolutionary biologists, medical practitioners, anthropologists, and ethicists to lay the groundwork for further collaboration and exploration. The range of overlap is surprisingly broad and potentially invaluable.