The evolution of barriers to exploitation: Sometimes the Red Queen can take a break.

We propose a general barrier theory as an evolutionary framework for understanding coevolutionary effects of conflicts of interest in natural and human systems. It is generalized from the barrier theory of cancer, which describes how cancer develops through the evasion of mechanisms, that block unregulated cellular reproduction and survival. Barriers are naturally evolved or artificially implemented mechanisms for blocking exploitation; restraints are mechanisms that impede but do not block exploitation.

Inflammation, infection and depression: an evolutionary perspective.

The evolutionary basis for clinical depression is not well understood. A growing body of literature that is not based on evolutionary logic links inflammation to depression. Integration of these findings with an evolutionary framework for depression, however, needs to address the reasons why the body's inflammatory response would be regulated so poorly that it would result in incapacitating depression.

Urban environment and cancer in wildlife: available evidence and future research avenues.

While it is generally known that the risk of several cancers in humans is higher in urban areas compared with rural areas, cancer is often deemed a problem of human societies with modern lifestyles. At the same time, more and more wild animals are affected by urbanization processes and are faced with the need to adapt or acclimate to urban conditions. These include, among other things, increased exposure to an assortment of pollutants (e.

The scope of viral causation of human cancers: interpreting virus density from an evolutionary perspective.

Most known oncogenic viruses of humans use DNA as their genomic material. Research over the past quarter century has revealed that their oncogenicity results largely from direct interference with barriers to oncogenesis. In contrast to viruses that have been accepted causes of particular cancers, candidate viral causes tend to have fewer viral than cellular genomes in the tumours.

Natural Selection, The Microbiome, and Public Health.

The microbiome is composed of hundreds of interacting species that have co-evolved with the host and alterations in microbiome composition have been associated with health and disease. Insights from evolutionary ecology may aid efforts to ameliorate microbiome-associated diseases. One step toward this goal involves recognition that the idea of commensalism has been applied too broadly to human/microbe symbioses.

Human activities might influence oncogenic processes in wild animal populations.

Based on the abundant studies available on humans showing clear associations between rapid environmental changes and the rate of neoplasia, we propose that human activities might increase cancer rate in wild populations through numerous processes. Most of the research on this topic has concentrated on wildlife cancer prevalence in environments that are heavily contaminated with anthropogenic chemicals. Here, we propose that human activities might also increase cancer rate in wild populations through additional processes including light pollution, accidental (for example, human waste) or intentional (for example, bird feeders) wildlife feeding (and the associated change of diet), or reduction of genetic diversity in human-impacted habitats.

Ancient cancers and infection-induced oncogenesis.

Cancers have been reported in bone and soft tissue of ancient agricultural populations. Fossilized bones from prehistoric periods provide evidence of tumors but only one example of cancer. Difficulties in diagnosing the causes of lesions in mummified tissue and fossilized bone, and in interpreting the prevalence of cancers from remains, draw attention to the need for complementary approaches to assess the occurrence of cancer in ancient populations.

Sexually Transmitted Pathogens, Depression, and Other Manifestations Associated with Premenstrual Syndrome.

This study investigated whether sexually transmitted infections and lifestyle variables are associated with premenstrual syndrome (PMS) as well as particular manifestations commonly associated with PMS. Data were gathered from medical records of 500 regularly cycling women. The following infectious agents were investigated: human papillomavirus, Chlamydia trachomatis, Neisseria gonorrheae, Gardnerella vaginalis, Candida albicans, and Trichomonas vaginalis.

Evolutionary perspective of cancer: myth, metaphors, and reality.

The evolutionary perspective of cancer (which origins and dynamics result from evolutionary processes) has gained significant international recognition over the past decade and generated a wave of enthusiasm among researchers. In this context, several authors proposed that insights into evolutionary and adaptation dynamics of cancers can be gained by studying the evolutionary strategies of organisms. Although this reasoning is fundamentally correct, in our opinion, it contains a potential risk of excessive adaptationism, potentially leading to the suggestion of complex adaptations that are unlikely to evolve among cancerous cells.

Infection and cancer in multicellular organisms.

Evolutionary considerations suggest that oncogenic infections should be pervasive among animal species. Infection-associated cancers are well documented in humans and domestic animals, less commonly reported in undomesticated captive animals, and rarely documented in nature. In this paper, we review the literature associating infectious agents with cancer to evaluate the reasons for this pattern.

Joint infectious causation of human cancers.

Joint infectious causation of cancer has been accepted in a few well-studied instances, including Burkitt's lymphoma and liver cancer. In general, evidence for the involvement of parasitic agents in oncogenesis has expanded, and recent advances in the application of molecular techniques have revealed specific mechanisms by which host cells are transformed. Many parasites evolve to circumvent immune-mediated detection and destruction and to control critical aspects of host cell reproduction and survival: cell proliferation, apoptosis, adhesion, and immortalization.

An evolutionary perspective on the causes and treatment of inflammatory bowel disease.

Purpose Of Review: To use insights from evolutionary biology to assess the current evidence for the causes, treatment, and prevention of inflammatory bowel disease (IBD).

Recent Findings: When analyzed in the context of evolutionary adaptation, recent assessments of genetic, microbial, and environmental associations with IBD implicate infectious causation.

Summary: An evolutionary perspective provides insight into the causes of IBD, interpretation of its manifestations, and assessment of interventions.

Toward a general evolutionary theory of oncogenesis.

We propose an evolutionary framework, the barrier theory of cancer, which is based on the distinction between barriers to oncogenesis and restraints. Barriers are defined as mechanisms that prevent oncogenesis. Restraints, which are more numerous, inhibit but do not prevent oncogenesis.

Infection, mutation, and cancer evolution.

An understanding of oncogenesis can be fostered by an integration of mechanistic studies with evolutionary considerations, which help explain why these mechanisms occur. This integration emphasizes infections and mutations as joint essential causes for many cancers. It suggests that infections may play a broader causal role in oncogenesis than has been generally appreciated.

Evolution of virulence, environmental change, and the threat posed by emerging and chronic diseases.

Assessments of future threats posed by infection have focused largely on zoonotic, acute disease, under the rubric "emerging diseases." Evolutionary and epidemiological studies indicate, however, that particular aspects of infrastructure, such as protected water supplies, vector-proof housing, and health care facilities, protect against the emergence of zoonotic, acute infectious diseases. While attention in the global health community has focused on emerging diseases, there has been a concurrent, growing recognition that important chronic diseases, such as cancer, are often caused by infectious agents that are already widespread in human populations.

An evolutionary perspective on parasitism as a cause of cancer.

For the past half-century, the dominant paradigm of oncogenesis has been mutational changes that disregulate cellular control of proliferation. Parasitic causes of cancer were first incorporated into this paradigm by suggesting mechanisms through which parasitism might increase mutational damage, such as generation of mutagenic compounds during immunological activity. The growing recognition of the molecular mechanisms of pathogen-induced oncogenesis and the difficulty of generating oncogenic mutations without first having large populations of dysregulated cells, however, suggests that pathogens, particularly viruses, are major initiators of oncogenesis for many if not most cancers, and that the traditional mutation-driven process becomes the dominant process after this initiation.

Premenstrual syndrome: an evolutionary perspective on its causes and treatment.

Premenstrual syndrome is a collection of heterogeneous symptoms that are attributed to hormonal fluctuations and that vary among individuals for unknown reasons. We propose that much of what is labeled "premenstrual syndrome" is part of a broader set of infectious illnesses that are exacerbated by cyclic changes in immunosuppression, which are induced by cyclic changes in estrogen and progesterone. This cyclic defense paradigm accords with the literature on cyclic exacerbations of persistent infectious diseases and chronic diseases of uncertain cause.

Pathogen survival in the external environment and the evolution of virulence.

Recent studies have provided evolutionary explanations for much of the variation in mortality among human infectious diseases. One gap in this knowledge concerns respiratory tract pathogens transmitted from person to person by direct contact or through environmental contamination. The sit-and-wait hypothesis predicts that virulence should be positively correlated with durability in the external environment because high durability reduces the dependence of transmission on host mobility.

Evolution of virulence.

At the close of the 19th century, the germ theory had generated a new understanding of the causes of acute infectious diseases and revealed new directions for study. This understanding contributed to the greatest improvements in health in the history of medicine. At the end of the 20th century, the second stage of this disciplinary development is occurring.

Genes, germs, and schizophrenia: an evolutionary perspective.

Literature on schizophrenia and other mental illnesses has emphasized the compatibility of evidence with genetic causation without adequately considering alternative hypotheses of disease causation. Although some studies from the mid-20th century reported associations between certain pathogens and schizophrenia, only recently has the possibility of infectious causation of schizophrenia again become an active focus of research. Infectious causation of schizophrenia is still, however, generally regarded as less well demonstrated than genetic causation.

Timing of transmission and the evolution of virulence of an insect virus.

We used the nuclear polyhedrosis virus of the gypsy moth, Lymantria dispar, to investigate whether the timing of transmission influences the evolution of virulence. In theory, early transmission should favour rapid replication and increase virulence, while late transmission should favour slower replication and reduce virulence. We tested this prediction by subjecting one set of 10 virus lineages to early transmission (Early viruses) and another set to late transmission (Late viruses).

Evolutionary health promotion.

Health promotion's promise is enormous, but its potential is, as yet, unmatched by accomplishment. Life expectancy increases track more closely with economic prosperity and sanitary engineering than with strictly medical advances. Notable achievements in the past century--the decreased incidences of epidemic infections, dental caries, and stomach cancer--are owed to virologists, dentists, and (probably) refrigeration more than to physicians.

Mobility of Impatiens capensis flowers: effect on pollen deposition and hummingbird foraging.

Flexible pedicels are characteristic of birdpollinated plants, yet have received little attention in studies of hummingbird-flower interactions. A major implication of flexible pedicels is that flowers may move during pollination. We examined whether such motion affected interactions between ruby-throated hummingbirds (Archilochus colubris) and jewelweed (Impatiens capensis) by increasing pollen deposition and by altering the effectiveness of nectar removal.