The cliff edge model of the evolution of schizophrenia: Mathematical, epidemiological, and genetic evidence

How has schizophrenia, a condition that significantly reduces an individual's evolutionary fitness, remained common across generations and cultures? Numerous theories about the evolution of schizophrenia have been proposed, most of which are not consistent with modern epidemiological and genetic evidence. Here, we briefly review this evidence and explore the cliff edge model of schizophrenia. It suggests that schizophrenia is the extreme manifestation of a polygenic trait or a combination of traits that, within a normal range of variation, confer cognitive, linguistic, and/or social advantages. Only beyond a certain threshold, these traits precipitate the onset of schizophrenia and reduce fitness. We provide the first mathematical model of this qualitative concept and show that it requires only very weak positive selection of the underlying trait(s) to explain today's schizophrenia prevalence. This prediction, along with expectations about the effect size of schizophrenia risk alleles, are surprisingly well matched by empirical evidence. The cliff edge model predicts a dynamic change of selection of risk alleles, which explains the contradictory findings of evolutionary genetic studies.

An evolutionary medicine perspective on the cetacean pulmonary immune system - The first identification of SP-D and LBP in the bottlenose dolphin (Tursiops truncatus)

Evolutionary medicine expresses the present status of biomolecules affected by past evolutionary events. To clarify the whole picture of cetacean pneumonia, which is a major threat to cetaceans, their pulmonary immune system should be studied from the perspective of evolutionary medicine. In this in silico study, we focused on cetacean surfactant protein D (SP-D) and lipopolysaccharide-binding protein (LBP) as two representative molecules of the cetacean pulmonary immune system. Sequencing and analyzing SP-D and LBP in the bottlenose dolphin (Tursiops truncatus) lung and liver tissue collected post-mortem elucidated not only basic physicochemical properties but also their evolutionary background. This is the first study to report the sequences and expression of SP-D and LBP in the bottlenose dolphin. Besides, our findings also suggest the direction of an evolutionary arms race in the cetacean pulmonary immune system. These results have important positive implications for cetacean clinical medicine.

The pathological anatomical collection of the Natural History Museum Vienna

The pathological anatomical collection Vienna (Pathologisch-Anatomische Sammlung Wien; PASW) is a living and still growing research collection. It was established as early as 1796 as part of the Medical University of Vienna, acquired the status of an independent federal museum in 1971, and was assigned to the Natural History Museum Vienna in 2012. It houses a wide range of human wet and dry specimens and further objects, such as moulages, medical devices, microbiological and histological specimens, and a photo archive (approximately 50,000 objects), which, as a meaningful source, may contribute to disclosing not only aspects of the medical history and the development of corresponding museums in Vienna, but is also considered a collection of cultural and current scientific relevance, quite comparable to today's biobanks. Most of the tissue amassment represents wet organic specimens and human skeletons or skeletal elements representing, e.g., congenital and metabolic disorders, infectious diseases, injuries, neoplasms, or musculoskeletal diseases, basically collected as descriptive anatomical teaching aids. This article reviews the current medical issues on which research has been and is being conducted by including PASW specimens (hereby using the ICD-10 code), and the extent to and ethical conditions under which this important heritage could be used as a reference collection for clinical and bioanthropological (paleopathological and palaeoepidemiological) studies; finally, this article reflects on the value and future research prospects, taking into account different positions and the ongoing discussions in pathological anatomical human tissue collections.

Explanatory integration and integrated explanations in Darwinian medicine and evolutionary medicine

Recently, two research traditions that bring together evolutionary biology and medicine, that is to say, Darwinian medicine and evolutionary medicine, have been identified. In this paper, I analyse these two research traditions with respect to explanatory and interdisciplinary integration. My analysis shows that Darwinian medicine does not integrate medicine and evolutionary biology in any strong sense but does incorporate evolutionary concepts into medicine. I also show that backward-looking explanations in Darwinian medicine are not integrated proximate-and-ultimate explanations but functional explanations that include reference to evolutionary concepts. Nevertheless, explanations in Darwinian medicine have heuristic roles as they potentially contribute to conceptual change and tie pieces of knowledge from different fields of medical research together. I argue that Darwinian medicine is an "interfield" that fosters cross-disciplinary exchange between evolutionary biologists and medical researchers and practitioners based on division of labour and separation, rather than unity. Research in evolutionary medicine, on the other hand, happens at the intersection of evolutionary biology and medicine where the two disciplines are already integrated and is designed to produce entangled proximate-evolutionary explanations. My analysis thus adds another important aspect to the philosophical discussion on the distinction between Darwinian medicine and evolutionary medicine.

Gradistics: An underappreciated dimension in evolutionary space

The growth of complexity is an unsolved and underappreciated problem. We consider possible causes of this growth, hypotheses testing, molecular mechanisms, complexity measures, cases of simplification, and significance for biomedicine. We focus on a general ability of regulation, which is based on the growing information storage and processing capacities, as the main proxy of complexity. Natural selection is indifferent to complexity. However, complexification can be inferred from the same first principle, on which natural selection is founded. Natural selection depends on potentially unlimited reproduction under limited environmental conditions. Because of the demographic pressure, the simple ecological niches become fulfilled and diversified (due to species splitting and divergence). Diversification increases complexity of biocenoses. After the filling and diversification of simple niches, the more complex niches can arise. This is the 'atomic orbitals' (AO) model. Complexity has many shortcomings but it has an advantage. This advantage is ability to regulatory adaptation, including behavioral, formed in the evolution by means of genetic adaptation. Regulatory adaptation is much faster than genetic one because it is based on the information previously accumulated via genetic adaptation and learning. Regulatory adaptation further increases complexity of biocenoses. This is the 'regulatory advantage' (RA) model. The comparison of both models allows testable predictions. We focus on the animal evolution because of the appearance of higher regulatory level (nervous system), which is absent in other lineages, and relevance to humans (including biomedical aspects).

Evolution and disease

This essay questions evolutionary or Darwinian medicine for its uncritical adherence to evolutionary theory to explain diseases, which leaves aside the very vital process that transformed an "inert planet" into a "living one" where the nascent biological order subordinated the physicochemical one to prevail. The biological order is comparable to an "infinitely diverse harmonic concert", which has created and recreated, for eons, the environments conducive to its own permanence and evolution. The arrival of homo sapiens meant the cultural order emergence, which progressively supplanted, in its effects, the biological order by causing drastic and vertiginous changes in the planetary ecosystem that silenced the evolutionary process "without time to manifest". Adaptation as an ability to overcome adverse situations is a non-sense in the "harmonic concert"; instead, it is characteristic of the cultural order that imposes inhospitable and stressful environments on humans as inescapable adaptive demands. The vital quality of the biological order is the sequential anticipation of situations of interaction with significant objects in the environment, which enables the consummation of basic vital activities, emblematic of the state of maturity of living beings. To think that evolution explains chronic diseases is not only illusory but counterproductive because it covers up the root of our problems: a humanity in constant disharmony between bellicose ethnocentrisms, perpetrator of planetary devastation, whose supreme value is profit without limits.

Not just a cousin of the naked mole-rat: Damaraland mole-rats offer unique insights into biomedicine

Evolutionary medicine has been a fast-growing field of biological research in the past decade. One of the strengths of evolutionary medicine is to use non-traditional model organisms which often exhibit unusual characteristics shaped by natural selection. Studying these unusual traits could provide valuable insight to understand biomedical questions, since natural selection likely discovers solutions to those complex biological problems. Because of many unusual traits, the naked mole-rat (NMR) has attracted attention from different research areas such as aging, cancer, and hypoxia- and hypercapnia-related disorders. However, such uniqueness of NMR physiology may sometimes make the translational study to human research difficult. Damaraland mole-rat (DMR) shares multiple characteristics in common with NMR, but shows higher degree of similarity with human in some aspects of their physiology. Research on DMR could therefore offer alternative insights and might bridge the gap between experimental findings from NMR to human biomedical research. In this review, we discuss studies of DMR as an extension of the current set of model organisms to help better understand different aspects of human biology and disease. We hope to encourage researchers to consider studying DMR together with NMR. By studying these two similar but evolutionarily distinct species, we can harvest the power of convergent evolution and avoid the potential biased conclusions based on life-history of a single species.

Evolution of the DAN gene family in vertebrates

The DAN gene family (DAN, Differential screening-selected gene Aberrant in Neuroblastoma) is a group of genes that is expressed during development and plays fundamental roles in limb bud formation and digitation, kidney formation and morphogenesis and left-right axis specification. During adulthood the expression of these genes are associated with diseases, including cancer. Although most of the attention to this group of genes has been dedicated to understanding its role in physiology and development, its evolutionary history remains poorly understood. Thus, the goal of this study is to investigate the evolutionary history of the DAN gene family in vertebrates, with the objective of complementing the already abundant physiological information with an evolutionary context. Our results recovered the monophyly of all DAN gene family members and divide them into five main groups. In addition to the well-known DAN genes, our phylogenetic results revealed the presence of two new DAN gene lineages; one is only retained in cephalochordates, whereas the other one (GREM3) was only identified in cartilaginous fish, holostean fish, and coelacanth. According to the phyletic distribution of the genes, the ancestor of gnathostomes possessed a repertoire of eight DAN genes, and during the radiation of the group GREM1, GREM2, SOST, SOSTDC1, and NBL1 were retained in all major groups, whereas, GREM3, CER1, and DAND5 were differentially lost.

Innovations are disproportionately likely in the periphery of a scientific network

The origins of innovation in science are typically understood using historical narratives that tend to be focused on small sets of influential authors, an approach that is rigorous but limited in scope. Here, we develop a framework for rigorously identifying innovation across an entire scientific field through automated analysis of a corpus of over 6000 documents that includes every paper published in the field of evolutionary medicine. This comprehensive approach allows us to explore statistical properties of innovation, asking where innovative ideas tend to originate within a field's pre-existing conceptual framework. First, we develop a measure of innovation based on novelty and persistence, quantifying the collective acceptance of novel language and ideas. Second, we study the field's conceptual landscape through a bibliographic coupling network. We find that innovations are disproportionately more likely in the periphery of the bibliographic coupling network, suggesting that the relative freedom allowed by remaining unconnected with well-established lines of research could be beneficial to creating novel and lasting change. In this way, the emergence of collective computation in scientific disciplines may have robustness-adaptability trade-offs that are similar to those found in other biosocial complex systems.

Evolution and medicine - The central role of anatomy

In medicine, there is an increasing number of publications that deal with or at least consider an evolutionary background. In zoology or comparative anatomy, work on evolutionary developments is taking on an ever-greater role in parallel. The pre-clinical (or pre-medical) phase in medical studies would be able to form a bridge between these related and yet so distant subjects but is currently completely evolution-free. This means that there is no consideration of the evolution of the healthy human being as a prerequisite for a systematic study of the evolutionary background in medicine. In this work the view is expressed that anatomy should be given a central, framework-giving and integrating role, which should urgently be actively pursued.

Evaluating alternative hypotheses to explain the downward trend in the indices of the COVID-19 pandemic death rate

BACKGROUND

In the ongoing Covid-19 pandemic, in the global data on the case fatality ratio (CFR) and other indices reflecting death rate, there is a consistent downward trend from mid-April to mid-November. The downward trend can be an illusion caused by biases and limitations of data or it could faithfully reflect a declining death rate. A variety of explanations for this trend are possible, but a systematic analysis of the testable predictions of the alternative hypotheses has not yet been attempted.

METHODOLOGY

We state six testable alternative hypotheses, analyze their testable predictions using public domain data and evaluate their relative contributions to the downward trend.

RESULTS

We show that a decline in the death rate is real; changing age structure of the infected population and evolution of the virus towards reduced virulence are the most supported hypotheses and together contribute to major part of the trend. The testable predictions from other explanations including altered testing efficiency, time lag, improved treatment protocols and herd immunity are not consistently supported, or do not appear to make a major contribution to this trend although they may influence some other patterns of the epidemic.

CONCLUSION

The fatality of the infection showed a robust declining time trend between mid April to mid November. Changing age class of the infected and decreasing virulence of the pathogen were found to be the strongest contributors to the trend.

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.

Quantifying simultaneous innovations in evolutionary medicine

To what extent do simultaneous innovations occur and are independently from each other? In this paper we use a novel persistent keyword framework to systematically identify innovations in a large corpus containing academic papers in evolutionary medicine between 2007 and 2011. We examine whether innovative papers occurring simultaneously are independent from each other by evaluating the citation and co-authorship information gathered from the corpus metadata. We find that 19 out of 22 simultaneous innovative papers do, in fact, occur independently from each other. In particular, co-authors of simultaneous innovative papers are no more geographically concentrated than the co-authors of similar non-innovative papers in the field. Our result suggests producing innovative work draws from a collective knowledge pool, rather than from knowledge circulating in distinct localized collaboration networks. Therefore, new ideas can appear at multiple locations and with geographically dispersed co-authorship networks. Our findings support the perspective that simultaneous innovations are the outcome of collective behavior.

Hypothesized behavioral host manipulation by SARS-CoV2/COVID-19 infection

Although not widely studied, behavioral host manipulation by various pathogens has been documented. Host manipulation is the process by which a pathogen evolves adaptations to manipulate the behavior of the host to maximize reproduction (Ro) of the pathogen. The most notable example is rabies. When a host is infected with the rabies virus it gets into the host's central nervous system and triggers hyper aggression. The virus is also present in the rabid animal's saliva so being bitten transmits the infection to a new host and the old host is left to eventually die if untreated. Toxoplasmosis is another example. When mice are infected they demonstrate a fearlessness toward cats, thus increasing their chances of being eaten. Toxoplasmosis needs the digestive tract of the feline to survive. Recent studies have shown that exposure to toxoplasmosis in humans (e.g., through cat feces) has also been associated with behavioral changes that are predicted to enhance the spread of the pathogen. Even the common influenza virus has been shown to selectively increase in-person sociality during the 48-hour incubation period, thus producing an obvious vector for transmission. Here we hypothesize that the novel coronavirus, SARS-CoV2, which produces the COVID-19 disease may produce similar host manipulations that maximize its transmission between humans.

Genomic history of the Italian population recapitulates key evolutionary dynamics of both Continental and Southern Europeans

BACKGROUND

The cline of human genetic diversity observable across Europe is recapitulated at a micro-geographic scale by variation within the Italian population. Besides resulting from extensive gene flow, this might be ascribable also to local adaptations to diverse ecological contexts evolved by people who anciently spread along the Italian Peninsula. Dissecting the evolutionary history of the ancestors of present-day Italians may thus improve the understanding of demographic and biological processes that contributed to shape the gene pool of European populations. However, previous SNP array-based studies failed to investigate the full spectrum of Italian variation, generally neglecting low-frequency genetic variants and examining a limited set of small effect size alleles, which may represent important determinants of population structure and complex adaptive traits. To overcome these issues, we analyzed 38 high-coverage whole-genome sequences representative of population clusters at the opposite ends of the cline of Italian variation, along with a large panel of modern and ancient Euro-Mediterranean genomes.

RESULTS

We provided evidence for the early divergence of Italian groups dating back to the Late Glacial and for Neolithic and distinct Bronze Age migrations having further differentiated their gene pools. We inferred adaptive evolution at insulin-related loci in people from Italian regions with a temperate climate, while possible adaptations to pathogens and ultraviolet radiation were observed in Mediterranean Italians. Some of these adaptive events may also have secondarily modulated population disease or longevity predisposition.

CONCLUSIONS

We disentangled the contribution of multiple migratory and adaptive events in shaping the heterogeneous Italian genomic background, which exemplify population dynamics and gene-environment interactions that played significant roles also in the formation of the Continental and Southern European genomic landscapes.

DNA viruses and cancer: insights from evolutionary biology

When it comes to understanding the exact mechanisms behind the virus induced cancers, we have often turned to molecular biology. It would be fair to argue that our understanding of cancers caused by viruses has significantly improved since the isolation of Epstein-Barr virus from Burkitt's lymphoma. However they are some important questions that remain unexplored like what advantage do viruses derive by inducing carcinogenesis? Why do viruses code for the so called oncogenes? Why DNA viruses are disproportionately linked to cancers? These questions have been addressed from the lens of evolutionary biology in this review. The evolutionary analysis of virus induced cancer suggests that persistent strategy of infection could be a stable strategy for DNA viruses and also the main culprit behind their tendency to cause cancer. The framework presented in the review not only explains wider observations about cancer caused by viruses but also offers fresh predictions to test the hypothesis.

A biocultural approach to psychiatric illnesses

RATIONALE

As a species, humans are vulnerable to numerous mental disorders, including depression and schizophrenia. This susceptibility may be due to the evolution of our large, complex brains, or perhaps because these illnesses counterintuitively confer some adaptive advantage. Additionally, cultural and biological factors may contribute to susceptibility and variation in mental illness experience and expression. Taking a holistic perspective could strengthen our understanding of these illnesses in diverse cultural contexts.

OBJECTIVES

This paper reviews some of these potential factors and contextualizes mental disorders within a biocultural framework.

RESULTS

There is growing evidence that suggests cultural norms may influence inflammation, neurotransmitters, and neurobiology, as well as the illness experience. Specific examples include variation in schizophrenia delusions between countries, differences in links between inflammation and emotion between the United States and Japan, and differences in brain activity between Caucasian and Asian participants indicating that cultural values may moderate cognitive processes related to social cognition and interoception.

CONCLUSIONS

Research agendas that are grounded in an appreciation of biocultural diversity as it relates to psychiatric illness represent key areas for truly interdisciplinary research that can result in culturally sensitive treatments and highlight possible biological variation affecting medical treatment.

Evolutionary Medicine of Retroviruses in the Human Genome

Humans are infected with many viruses, and the immune system mostly removes viruses and the infected cells. However, certain viruses have entered the human genome. Of the human genome, ∼45% is composed of transposable elements (long interspersed nuclear elements [LINEs], short interspersed nuclear elements [SINEs] and transposons) and 5-8% is derived from viral sequences with similarity to infectious retroviruses. If integration of retrovirus occurs in a germline, the integrated viral sequences are heritable. Accumulation of viral sequences has created the current human genome. This article summarizes recent studies of retroviruses in humans and bridges clinical fields and evolutionary genetics. First, we report the repertories of human-infective retroviruses. Second, we review endogenous retroviruses in the human genome and diseases associated with endogenous retroviruses. Third, we discuss the biological functions of endogenous retroviruses and propose the concept of accelerated human evolution via viruses. Finally, we present perspectives of virology in the field of evolutionary medicine.

An Evolutionary Perspective on the Impact of Genomic Copy Number Variation on Human Health

Copy number variants (CNVs), deletions and duplications of segments of DNA, account for at least five times more variable base pairs in humans than single-nucleotide variants. Several common CNVs were shown to change coding and regulatory sequences and thus dramatically affect adaptive phenotypes involving immunity, perception, metabolism, skin structure, among others. Some of these CNVs were also associated with susceptibility to cancer, infection, and metabolic disorders. These observations raise the possibility that CNVs are a primary contributor to human phenotypic variation and consequently evolve under selective pressures. Indeed, locus-specific haplotype-level analyses revealed signatures of natural selection on several CNVs. However, more traditional tests of selection which are often applied to single-nucleotide variation often have diminished statistical power when applied to CNVs because they often do not show strong linkage disequilibrium with nearby variants. Recombination-based formation mechanisms of CNVs lead to frequent recurrence and gene conversion events, breaking the linkage disequilibrium involving CNVs. Similar methodological challenges also prevent routine genome-wide association studies to adequately investigate the impact of CNVs on heritable human disease. Thus, we argue that the full relevance of CNVs to human health and evolution is yet to be elucidated. We further argue that a holistic investigation of formation mechanisms within an evolutionary framework would provide a powerful framework to understand the functional and biomedical impact of CNVs. In this paper, we review several cases where studies reveal diverse evolutionary histories and unexpected functional consequences of CNVs. We hope that this review will encourage further work on CNVs by both evolutionary and medical geneticists.

Reframing HIV Stigma and Fear : Considerations from Social-ecological and Evolutionary Theories of Reproduction

HIV stigma and fears surrounding the disease pose a challenge for public health interventions, particularly those that target pregnant women. In order to reduce stigma and improve the lives of vulnerable populations, researchers have recognized a need to integrate different types of support at various levels. To better inform HIV interventions, the current study draws on social-ecological and evolutionary theories of reproduction to predict stigma and fear of contracting HIV among pregnant women in South India. The aims of this study were twofold: compare the social-ecological model to a modified maternal-fetal protection model and test a combined model that included strong predictors from each model. The study took place in 2008-2011 in Mysore District, Karnataka, India. Using data from a cross-sectional survey and biological indicators of health, we statistically modeled social-ecological variables representing individual, interpersonal, and community/institutional levels. Participants were 645 pregnant women. The social-ecological and combined models were the best-fitting models for HIV-related stigma, and the combined model was the best fit for HIV-related fear. Our findings suggest that combining reproductive life history factors along with individual, interpersonal, and community/institutional factors are significant indicators of HIV-related stigma and fear. Results of this study support a multifaceted approach to intervention development for HIV-related stigma and fear. The combined model in this study can be used as a predictive model for future research focused on HIV stigma and fear, with the intent that dual consideration of social-ecological and evolutionary theories will improve public health communication efforts.

Allergy in an Evolutionary Framework

Respiratory allergy including bronchial asthma and food allergy have gained epidemic character in the last decades in industrialized countries. Much has been learned with respect to the pathophysiology of allergic disease and this has facilitated specific therapies. Allergy is a chronic disease, and being so prevalent claims to search for evolutionary causes of the general susceptibility of humans as a species to react to environmental antigens in a Th2 type immune reaction with IgE production. In an evolutionary analysis of Allergy, necessary questions addressed in this review are "Why does IgE exist or why did IgE evolve?" as well as from the point of view of the mismatch hypothesis, "Why is there an Allergy epidemic?" Recent studies on the possible biological and protective role of IgE against parasites, arthropods, venoms or toxins are challenging the widely accepted definition of allergens as generally innocuous antigens. Combining the immunologic danger model and the toxin hypothesis for allergies, the allergic response could have evolved with an adaptive value and allergens could be proxies for other putative noxious agents. The last decades yielded with vast molecular data of allergens. With available bioinformatics tools, we therefore also describe that evolutionary theory could be applied to prevent allergy, estimate cross-reactivity, to design allergen-specific immunotherapy and to assess the risks of novel foods.

Evidence that DNA repair genes, a family of tumor suppressor genes, are associated with evolution rate and size of genomes

Adaptive radiation and evolutionary stasis are characterized by very different evolution rates. The main aim of this study was to investigate if any genes have a special role to a high or low evolution rate. The availability of animal genomes permitted comparison of gene content of genomes of 24 vertebrate species that evolved through adaptive radiation (representing high evolutionary rate) and of 20 vertebrate species that are considered as living fossils (representing a slow evolutionary rate or evolutionary stasis). Mammals, birds, reptiles, and bony fishes were included in the analysis. Pathway analysis was performed for genes found to be specific in adaptive radiation or evolutionary stasis respectively. Pathway analysis revealed that DNA repair and cellular response to DNA damage are important (false discovery rate = 8.35 × 10⁻⁵; 7.15 × 10⁻⁶, respectively) for species evolved through adaptive radiation. This was confirmed by further genetic in silico analysis (p = 5.30 × 10⁻³). Nucleotide excision repair and base excision repair were the most significant pathways. Additionally, the number of DNA repair genes was found to be linearly related to the genome size and the protein number (proteome) of the 44 animals analyzed (p < 1.00 × 10⁻⁴), this being compatible with Drake’s rule. This is the first study where radiated and living fossil species have been genetically compared. Evidence has been found that cancer-related genes have a special role in radiated species. Linear association of the number of DNA repair genes with the species genome size has also been revealed. These comparative genetics results can support the idea of punctuated equilibrium evolution.

Frontiers in Molecular Evolutionary Medicine

This paper surveys some of the important insights that molecular evolution has contributed to evolutionary medicine; they include phage therapy, cancer biology, helminth manipulation of the host immune system, quality control of gametes, and pathogen outbreaks. Molecular evolution has helped to revolutionize our understanding of cancer, of autoimmune disease, and of the origin, spread, and pathogenesis of emerging diseases, where it has suggested new therapies, illuminated mechanisms, and revealed historical processes: all have practical therapeutic implications. While much has been accomplished, much remains to be done.

When Saying "Sorry" Isn't Enough: Is Some Suicidal Behavior a Costly Signal of Apology? : A Cross-Cultural Test

Lethal and nonlethal suicidal behaviors are major global public health problems. Much suicidal behavior (SB) occurs after the suicide victim committed a murder or other serious transgression. The present study tested a novel evolutionary model termed the Costly Apology Model (CAM) against the ethnographic record. The bargaining model (BRM) sees nonlethal suicidal behavior as an evolved costly signal of need in the wake of adversity. Relying on this same theoretical framework, the CAM posits that nonlethal suicidal behavior can sometimes serve as an honest signal of apology in the wake of committing a severe transgression, thereby repairing valuable social relationships. To test this hypothesis, the CAM was operationalized into a set of variables, and two independent coders coded 473 text records on suicidal behavior from 53 cultures from the probability sample of the Human Relations Area Files. The results indicated that in ethnographic accounts of suicidal behavior, transgressions, punishment, and shame were relatively common, supporting the CAM, but explicit motives to apologize and evidence of forgiveness were rare, contrary to the CAM. The theoretical variables of the CAM nevertheless formed a cluster distinct from the BRM, and a subset of cases of suicidal behavior were largely related to transgressions and other CAM variables rather than BRM or other variables. Support for the CAM varied widely across cultures, but there was evidence for it in every major geographical region. Exploratory analyses suggested that the CAM is potentially more likely to occur in response to severe conflicts concerning transgressions committed against nonkin. Furthermore, in text records that involved transgressions, male suicidal behavior was most frequently associated with murder, whereas female suicidal behavior was most frequently associated with sexual transgressions. In conclusion, the results provided mixed support for the hypothesis that some instances of suicidal behavior function to send a costly signal of apology to those harmed by a transgression.

'Evolutionary medicine' perspectives on Alzheimer's Disease: Review and new directions

Evolution by natural selection eliminates maladaptive traits from a species, and yet Alzheimer's Disease (AD) persists with rapidly increasing prevalence globally. This apparent paradox begs an explanation within the framework of evolutionary sciences. Here, I summarize and critique previously proposed theories to explain human susceptibility to AD, grouped into 8 distinct hypotheses based on the concepts of novel extension of the lifespan; lack of selective pressure during the post-reproductive phase; antagonistic pleiotropy; rapid brain evolution; delayed neuropathy by selection for grandmothering; novel alleles selected to delay neuropathy; by-product of selection against cardiovascular disease; and thrifty genotype. Subsequently, I describe a new hypothesis inspired by the concept of mismatched environments. Many of the factors that enhance AD risk today may have been absent or functioned differently before the modern era, potentially making AD a less common affliction for age-matched individuals before industrialization and for the majority of human history. Future research is needed to further explore whether changes in environments and lifestyles across human history moderate risk factors and susceptibility to AD.

Rethinking Causation in Cancer with Evolutionary Developmental Biology

Despite the productivity of basic cancer research, cancer continues to be a health burden to society because this research has not yielded corresponding clinical applications. Many proposed solutions to this dilemma have revolved around implementing organizational and policy changes related to cancer research. Here I argue for a different solution: a new conceptualization of causation in cancer. Neither the standard molecular biomarker approaches nor evolutionary biology approaches to cancer fully capture its complex causal dynamics, even when considered jointly. These approaches map on to Ernst Mayr's proximate-ultimate distinction, which is an inadequate conceptualization of causation in biological systems and makes it difficult to connect developmental and evolutionary viewpoints. I propose looking to evolutionary developmental biology (EvoDevo) to overcome the distinction and integrate the proximate and ultimate causal frameworks. I use the concepts of modularity and evolvability to show how an EvoDevo perspective can be manifested in cancer translational research. This perspective on causation in cancer is better suited for integrating the complexity of current empirical results and can facilitate novel developments in the investigation and clinical treatment of cancer.

Aging is an adaptation that selects in animals against disruption of homeostasis

During evolution, Muller's ratchet permanently generates deleterious germline mutations that eventually must be defused by selection. It seems widely held that cancer and aging-related diseases (ARDs) cannot contribute to this germline gene selection because they tail reproduction and thus occur too late, at the end of the life cycle. Here we posit however that by lessening the offspring's survival by proxy through diminishing parental care, they can still contribute to the selection. The hypothesis in detail: The widespread occurrence of aging in animals suggests that it is an adaptation. But to what benefit? Aging seems to have only drawbacks. In humans, ARDs cause today almost all mortality; they include heart disease, cerebrovascular disease, Alzheimer's disease, kidney disease and cancer. Compensation seems unthinkable. For cancer, the author proposed in a previous study a benefit to the species: purifying selection against deleterious germline genes that when expressed enhance intracellular energy dissipation. This multicausal energy dissipation, posited as the universal origin of cancer initiation, relates to cellular heat generation, disrupted metabolism, and inflammation. The organism reproduces during cancer's dormancy, and when approaching its end of life, the onset of cancer is accelerated in proportion to the cancer-initiating signal. Through cancer, the organism, now a parent, implements the self-actuated programmed death of Skulachev's phenoptosis. This "first death" enhances by proxy the offspring's chance of "second death" (or "double death") through diminished parental care. Repetition over generations realizes a purifying selection against genes causing energy dissipation. The removal of the deleterious germline gene mutations permanently generated by Muller's ratchet gives a benefit. We generalize, motivated by the parallels between cancer and aging, the purifying selection posited for cancer to aging. An ARD would be initiated in the organ by multicausal disruption of homeostasis, and be followed by dormancy and senescence until its onset near the end of the life cycle. Just as for cancer, the ARD eventually enhances double death, and the realized permanent selection gives a benefit to the species through the selection against germ line genes that disrupt homeostasis. Given their similarities, cancer and aging are combined in the posited Unified Cancer-Aging Adaptation (UCAA) model, which may be confirmed by next-generation sequencing data. Also because of the emerging important role of cellular senescence, the hypothesis may guide the development of therapies against both cancer and aging.

The emergence, maintenance, and demise of diversity in a spatially variable antibiotic regime

Antimicrobial resistance (AMR) is a growing global threat that, in the absence of new antibiotics, requires effective management of existing drugs. Here, we use experimental evolution of the opportunistic human pathogen Pseudomonas aeruginosa to explore how changing patterns of drug delivery modulates the spread of resistance in a population. Resistance evolves readily under both temporal and spatial variation in drug delivery and fixes rapidly under temporal, but not spatial, variation. Resistant and sensitive genotypes coexist in spatially varying conditions due to a resistance‐growth rate trade‐off which, when coupled to dispersal, generates negative frequency‐dependent selection and a quasi‐protected polymorphism. Coexistence is ultimately lost, however, because resistant types with improved growth rates in the absence of drug spread through the population. These results suggest that spatially variable drug prescriptions can delay but not prevent the spread of resistance and provide a striking example of how the emergence and eventual demise of biodiversity is underpinned by evolving fitness trade‐offs.

Revisiting the wandering womb: Oxytocin in endometriosis and bipolar disorder

Hippocrates attributed women's high emotionality - hysteria - to a 'wandering womb'. Although hysteria diagnoses were abandoned along with the notion that displaced wombs cause emotional disturbance, recent research suggests that elevated levels of oxytocin occur in both bipolar disorder and endometriosis, a gynecological condition involving migration of endometrial tissue beyond the uterus. We propose and evaluate the hypothesis that elevated oxytocinergic system activity jointly contributes to bipolar disorder and endometriosis. First, we provide relevant background on endometriosis and bipolar disorder, and then we examine evidence for comorbidity between these conditions. We next: (1) review oxytocin's associations with personality traits, especially extraversion and openness, and how they overlap with bipolar spectrum traits; (2) describe evidence for higher oxytocinergic activity in both endometriosis and bipolar disorder; (3) examine altered hypothalamic-pituitary-gonadal axis functioning in both conditions; (4) describe data showing that medications that treat one condition can improve symptoms of the other; (5) discuss fitness-related impacts of endometriosis and bipolar disorder; and (6) review a pair of conditions, polycystic ovary syndrome and autism, that show evidence of involving reduced oxytocinergic activity, in direct contrast to endometriosis and bipolar disorder. Considered together, the bipolar spectrum and endometriosis appear to involve dysregulated high extremes of normally adaptive pleiotropy in the female oxytocin system, whereby elevated levels of oxytocinergic activity coordinate outgoing sociality with heightened fertility, apparently characterizing, overall, a faster life history. These findings should prompt a re-examination of how mind-body interactions, and the pleiotropic endocrine systems that underlie them, contribute to health and disease.

The evolutionary logic of sepsis

The recently proposed Microbiome Mutiny Hypothesis posits that members of the human microbiome obtain information about the host individuals' health status and, when host survival is compromised, switch to an intensive exploitation strategy to maximize residual transmission. In animals and humans, sepsis is an acute systemic reaction to microbes invading the normally sterile body compartments. When induced by formerly mutualistic or neutral microbes, possibly in response to declining host health, sepsis appears to fit the 'microbiome mutiny' scenario except for its apparent failure to enhance transmission of the causative organisms. We propose that the ability of certain species of the microbiome to induce sepsis is not a fortuitous side effect of within-host replication, but rather it might, in some cases, be the result of their adaptive evolution. Whenever host health declines, inducing sepsis can be adaptive for those members of the healthy human microbiome that are capable of colonizing the future cadaver and spread by cadaver-borne transmission. We hypothesize that such microbes might exhibit switches along the 'mutualist - lethal pathogen - decomposer - mutualist again' scenario, implicating a previously unsuspected, surprising level of phenotypic plasticity. This hypothesis predicts that those species of the healthy microbiome that are recurring causative agents of sepsis can participate in the decomposition of cadavers, and can be transmitted as soil-borne or water-borne infections. Furthermore, in individual sepsis cases, the same microbial clones that dominate the systemic infection that precipitates sepsis, should also be present in high concentration during decomposition following death: this prediction is testable by molecular fingerprinting in experimentally induced animal models. Sepsis is a leading cause of human death worldwide. If further research confirms that some cases of sepsis indeed involve the 'mutiny' (facultative phenotypic switching) of normal members of the microbiome, then new strategies could be devised to prevent or treat sepsis by interfering with this process.

Evolution of the α2-adrenoreceptors in vertebrates: ADRA2D is absent in mammals and crocodiles

Evolutionary studies of genes that have been functionally characterized and whose variation has been associated with pathological conditions represent an opportunity to understand the genetic basis of pathologies. α₂-Adrenoreceptors (ADRA2) are a class of G protein-coupled receptors that regulate several physiological processes including blood pressure, platelet aggregation, insulin secretion, lipolysis, and neurotransmitter release. This gene family has been extensively studied from a molecular/physiological perspective, yet much less is known about its evolutionary history. Accordingly, the goal of this study was to investigate the evolutionary history of α₂-adrenoreceptors (ADRA2) in vertebrates. Our results show that in addition to the three well-recognized α₂-adrenoreceptor genes (ADRA2A, ADRA2B and ADRA2C), we recovered a clade that corresponds to the fourth member of the α₂-adrenoreceptor gene family (ADRA2D). We also recovered a clade that possesses two ADRA2 sequences found in two lamprey species. Furthermore, our results show that mammals and crocodiles are characterized by possessing three α₂-adrenoreceptor genes, whereas all other vertebrate groups possess the full repertoire of α₂-adrenoreceptor genes. Among vertebrates ADRA2D seems to be a dispensable gene, as it was lost two independent times during the evolutionary history of the group. Additionally, we found that most examined species possess the most common alleles described for humans; however, there are cases in which non-human mammals possess the alternative variant. Finally, transcript abundance profiles revealed that during the early evolutionary history of gnathostomes, the expression of ADRA2D in different taxonomic groups became specialized to different tissues, but in the ancestor of sarcopterygians this specialization would have been lost.

Traditional Mediterranean and European herbal medicines

ETHNOPHARMACOLOGICAL RELEVANCE

Written history allows tracing back Mediterranean and European medical traditions to Greek antiquity. The epidemiological shift triggered by the rise of modern medicine and industrialization is reflected in contemporary reliance and preferences for certain herbal medicines.

MATERIALS AND METHODS

We sketch the development and transmission of written herbal medicine through Mediterranean and European history and point out the opportunity to connect with modern traditions.

RESULTS

An ethnopharmacological database linking past and modern medical traditions could serve as a tool for crosschecking contemporary ethnopharmacological field-data as well as a repository for data mining. Considering that the diachronic picture emerging from such a database has an epidemiological base this could lead to new hypotheses related to evolutionary medicine.

CONCLUSION

The advent of systems pharmacology and network pharmacology opens new perspectives for studying past and current herbal medicine. Since a large part of modern drugs has its roots in ancient traditions one may expect new leads for drug development from novel systemic studies, as well as evidence for the activity of certain herbal preparations.

[Evolutionary medicine: A new look on health and disease]

Evolutionary medicine represents an innovative approach deriving from evolutionary biology. It includes the initial Darwin's view, its actualization in the light of progresses in genetics and also dissident theories (i.e. non gene-based) particularly epigenetics. This approach enables us to reconsider the pathophysiology of numerous diseases, as for instance, infection, and our so-called diseases of civilization especially obesity, type 2 diabetes, allergy or cancer. Evolutionary medicine may also improve our knowledge regarding inter-individual variation in susceptibility to disease or drugs. Furthermore, it points out the impact of our behaviors and environment on the genesis of a series of diseases.

Evolution of the β-adrenoreceptors in vertebrates

The study of the evolutionary history of genes related to human disease lies at the interface of evolution and medicine. These studies provide the evolutionary context on which medical researchers should work, and are also useful in providing information to suggest further genetic experiments, especially in model species where genetic manipulations can be made. Here we studied the evolution of the β-adrenoreceptor gene family in vertebrates with the aim of adding an evolutionary framework to the already abundant physiological information. Our results show that in addition to the three already described vertebrate β-adrenoreceptor genes there is an additional group containing cyclostome sequences. We suggest that β-adrenoreceptors diversified as a product of the two whole genome duplications that occurred in the ancestor of vertebrates. Gene expression patterns are in general consistent across species, suggesting that expression dynamics were established early in the evolutionary history of vertebrates, and have been maintained since then. Finally, amino acid polymorphisms that are associated to pathological conditions in humans appear to be common in non-human mammals, suggesting that the phenotypic effects of these mutations depend on epistatic interaction with other positions. The evolutionary analysis of the β-adrenoreceptors delivers new insights about the diversity of these receptors in vertebrates, the evolution of the expression patterns and a comparative perspective regarding the polymorphisms that in humans are linked to pathological conditions.

Evolutionary history of the reprimo tumor suppressor gene family in vertebrates with a description of a new reprimo gene lineage

Genes related to human diseases should be natural targets for evolutionary studies, since they could provide clues regarding the genetic bases of pathologies and potential treatments. Here we studied the evolution of the reprimo gene family, a group of tumor-suppressor genes that are implicated in p53-mediated cell cycle arrest. These genes, especially the reprimo duplicate located on human chromosome 2, have been associated with epigenetic modifications correlated with transcriptional silencing and cancer progression. We demonstrate the presence of a third reprimo lineage that, together with the reprimo and reprimo-like genes, appears to have been differentially retained during the evolutionary history of vertebrates. We present evidence that these reprimo lineages originated early in vertebrate evolution and expanded as a result of the two rounds of whole genome duplications that occurred in the last common ancestor of vertebrates. The reprimo gene has been lost in birds, and the third reprimo gene lineage has been retained in only a few distantly related species, such as coelacanth and gar. Expression analyses revealed that the reprimo paralogs are mainly expressed in the nervous system. Different vertebrate lineages have retained different reprimo paralogs, and even in species that have retained multiple copies, only one of them is heavily expressed.

Ancient pathogen-driven adaptation triggers increased susceptibility to non-celiac wheat sensitivity in present-day European populations

BACKGROUND

Non-celiac wheat sensitivity is an emerging wheat-related syndrome showing peak prevalence in Western populations. Recent studies hypothesize that new gliadin alleles introduced in the human diet by replacement of ancient wheat with modern varieties can prompt immune responses mediated by the CXCR3-chemokine axis potentially underlying such pathogenic inflammation. This cultural shift may also explain disease epidemiology, having turned European-specific adaptive alleles previously targeted by natural selection into disadvantageous ones.

METHODS

To explore this evolutionary scenario, we performed ultra-deep sequencing of genes pivotal in the CXCR3-inflammatory pathway on individuals diagnosed for non-celiac wheat sensitivity and we applied anthropological evolutionary genetics methods to sequence data from worldwide populations to investigate the genetic legacy of natural selection on these loci.

RESULTS

Our results indicate that balancing selection has maintained two divergent CXCL10/CXCL11 haplotypes in Europeans, one responsible for boosting inflammatory reactions and another for encoding moderate chemokine expression.

CONCLUSIONS

This led to considerably higher occurrence of the former haplotype in Western people than in Africans and East Asians, suggesting that they might be more prone to side effects related to the consumption of modern wheat varieties. Accordingly, this study contributed to shed new light on some of the mechanisms potentially involved in the disease etiology and on the evolutionary bases of its present-day epidemiological patterns. Moreover, overrepresentation of disease homozygotes for the dis-adaptive haplotype plausibly accounts for their even more enhanced CXCR3-axis expression and for their further increase in disease risk, representing a promising finding to be validated by larger follow-up studies.

Human compulsivity: A perspective from evolutionary medicine

Biological explanations address not only proximal mechanisms (for example, the underlying neurobiology of obsessive-compulsive disorder), but also distal mechanisms (that is, a consideration of how particular neurobiological mechanisms evolved). Evolutionary medicine has emphasized a series of explanations for vulnerability to disease, including constraints, mismatch, and tradeoffs. The current paper will consider compulsive symptoms in obsessive-compulsive and related disorders and behavioral addictions from this evolutionary perspective. It will argue that while obsessive-compulsive disorder (OCD) is typically best conceptualized as a dysfunction, it is theoretically and clinically valuable to understand some symptoms of obsessive-compulsive and related disorders in terms of useful defenses. The symptoms of behavioral addictions can also be conceptualized in evolutionary terms (for example, mismatch), which in turn provides a sound foundation for approaching assessment and intervention.

The nutritional consequences of pregnancy sickness : A critique of a hypothesis

The purpose of this paper is to assess Profet's (1992) and others' hypothesis that nausea and vomiting in pregnancy (NVP) is adaptive. A number of studies have found an association between NVP and a decreased risk for early fetal loss (<20 weeks). It is assumed that the adaptive benefits of improved survivorship associated with NVP outweigh the minimal nutritional consequences. However, in populations that experience marginal levels of nutrition, NVP may have important nutritional consequences. To test these potential consequences, a study on NVP, nutritional status, and pregnancy outcome was conducted among Turkana pastoralists, who experience seasonal and chronic nutritional stress. Interviews and anthropometric assessments were conducted on 68 pregnant Turkana women of Kenya during a 1993-1994 field season. The results from the case study suggest that women who experience NVP do encounter nutritional consequences in the later stages of pregnancy and are more likely to experience poor pregnancy outcomes. These results suggest that NVP may not be adaptive in all environmental settings, particularly among marginally nourished populations.

Challenging the Inevitability of Prostate Enlargement: Low Levels of Benign Prostatic Hyperplasia Among Tsimane Forager-Horticulturalists

BACKGROUND

Often considered an inevitable part of male aging, benign prostatic hyperplasia (BPH) is the most common non-life threatening disease to affect men in Western populations. We examine age-related change in prostate size and BPH risk and related serum biomarkers among the Tsimane Amerindians of the Bolivian Amazon who live a traditional lifestyle of hunting and small-scale horticulture. The Tsimane are a critical case study for understanding the etiology of BPH as they have low levels of obesity and metabolic syndrome, as well as lower levels of testosterone than age matched U.S. males, factors associated with BPH in previous research.

METHODS

Ultrasounds were conducted on 348 men aged 28-89 years (median age 56 years). Testosterone, prostate specific antigen, sex hormone binding globulin, and glycosylated hemoglobin were examined in relationship to prostate size and BPH.

RESULTS

Tsimane have less than half of the BPH prevalence experienced by U.S. men, and prostate volumes 62.6% smaller. While Tsimane have low levels of testosterone and subclinical levels of metabolic syndrome compared to U.S. men, Tsimane with high testosterone were more likely to experience BPH, as were those with higher glycosylated hemoglobin, suggesting targets for clinical interventions to reduce BPH.

CONCLUSIONS

These results have clinical significance for the growing number of men taking testosterone supplementation; even at low levels the additional testosterone exposure could be placing these men at higher risk of BPH. Overall, these data suggest that BPH may not have been an inevitable part of male aging throughout human evolutionary history.

The evolution of sex differences in disease

It is now becoming widely recognized that there are important sex differences in disease. These include rates of disease incidence, symptoms and age of onset. These differences between the sexes can be seen as a subset of the more general phenomenon of sexual dimorphism of quantitative phenotypes. From a genetic point of view, this is paradoxical, since the vast majority of genetic material is shared between the sexes. How can males and females differ in so many ways and yet have a common genetic code? Traditionally, the modifying action of hormones has been offered as a solution to this paradox, but experiments disentangling the effects of hormones and sex-chromosomes have shown that this cannot be the sole explanation. In this review, I outline current ideas about the evolutionary origins of sex differences in phenotypes, with a particular focus on how sex differences in disease can arise. I also discuss how sex differences in themselves can generate new risk factors for disease, in effect becoming a new environmental factor, as well as briefly reviewing more general evidence for sexually antagonistic selection and genetic variation within humans. Taking an evolutionary view on sex differences in disease provides an opportunity for greater understanding of mechanisms of disease and as such provides a clear motivation for clinicians to explore how therapies may be tailored to the individual in a sex-dependent way.

Darwinian medicine and psoriasis

Darwinian medicine, or evolutionary medicine, regards some pathological conditions as attempts by the organism to solve a problem or develop defense mechanisms. At certain stages of human evolution, some diseases may have conferred a selective advantage. Psoriasis is a high-penetrance multigenic disorder with prevalence among whites of up to 3%. Psoriatic lesions have been linked with enhanced wound-healing qualities and greater capacity to fight infection. Leprosy, tuberculosis, and infections caused by viruses similar to human immunodeficiency virus have been postulated as environmental stressors that may have selected for psoriasis-promoting genes in some human populations. The tendency of patients with severe psoriasis to develop metabolic syndrome may reflect the body's attempt to react to environmental stresses and warning signs by triggering insulin resistance and fat storage.

Childhood absence epilepsy successfully treated with the paleolithic ketogenic diet

Introduction

Childhood absence epilepsy is an epilepsy syndrome responding relatively well to the ketogenic diet with one-third of patients becoming seizure-free. Less restrictive variants of the classical ketogenic diet, however, have been shown to confer similar benefits. Beneficial effects of high fat, low-carbohydrate diets are often explained in evolutionary terms. However, the paleolithic diet itself which advocates a return to the human evolutionary diet has not yet been studied in epilepsy.

Results

Here, we present a case of a 7-year-old child with absence epilepsy successfully treated with the paleolithic ketogenic diet alone. In addition to seizure freedom achieved within 6 weeks, developmental and behavioral improvements were noted. The child remained seizure-free when subsequently shifted toward a paleolithic diet.

Conclusion

It is concluded that the paleolithic ketogenic diet was effective, safe and feasible in the treatment of this case of childhood absence epilepsy.

Sickness and healing and the evolutionary foundations of mind and minding

Disease represents a principal tentacle of natural selection and a staple theme of evolutionary medicine. However, it is through a small portal of entry and a very long lineage that disease as sickness entered behavioural spaces and human consciousness. This has a long evolutionary history. Anyone interested in the origins of medicine and psychiatry as social institution has to start with analysis of how mind and body were conceptualised and played out behaviourally following the pongid/hominin split and thereafter. The early evolution of medicine provides a template for clarifying elemental characteristics of mind and minding. Sickness and healing in chimpanzees represents an early manifestation of (ethno) medicine, termed a behavioural tradition, which is found played out in routines of helping, caring, and healing as well as other social behaviours. Chimpanzees seem to know they are sick since they resort to self-medication when exhibiting signs and symptoms of disease. Also, they help those exhibiting physical and cognitive disability. Among hominins, awareness of consequences and implications of sickness and coping with them represented an important feature of human consciousness and a major factor in the origins of vaunted human abilities involving language, cognition, and culture as we know them. A philosophical examination of the early evolution of sickness and healing provides a window into an understanding of evolving human capacities such as self-awareness, awareness and implications of suffering, theory of mind, altruism, conceptual grasp of sickness and healing and morality.