Holly Swain Ewald

University of Louisville | UL · Department of Biology

Individuals who are minoritized as a result of race, sexual identity, gender, or socioeconomic status experience a higher prevalence of many diseases. Understanding the biological processes that cause and maintain these socially driven health inequities is essential for addressing them. The gut microbiome is strongly shaped by host environments and...

The barrier theory of cancer integrates environmental, genetic, and infectious contributions to oncogenesis into a single framework. The full spectrum of symbiotic influences on oncogenesis, however, still needs to be brought into this framework, particularly for symbionts that are classified as commensals or mutualists. This paper contributes to t...

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 po...

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...

Medicine is grounded in the natural sciences, among which biology stands out with regard to the understanding of human physiology and conditions that cause dysfunction. Ironically, evolutionary biology is a relatively disregarded field. One reason for this omission is that evolution is deemed a slow process. Indeed, macroanatomical features of our...

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 comm...

Infectious agents are accepted causes of many cancers of humans and domesticated animals, but reports of infection-induced cancers in nature are relatively rare. Human pathogens, particularly viruses, are now known to cause cancer by sophisticated mechanisms that compromise barriers to cancer. These mechanisms have evolved convergently in different...

A balanced approach to the causes of cancer requires assessment of genetic, environmental, and infectious influences and the interactions among them. An evolutionary perspective provides a framework for such assessments because evolutionary selection acts on cells during the process of oncogenesis, on individuals to generate protection against onco...

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, Ch...

Exacerbations of chronic diseases that are known or suspected to be caused by infection near the onset of menses suggest that PMS may actually be a collection of manifestations of unidentified chronic infectious diseases.

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...

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 tran...

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...

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. Processes that compromise barriers are essential causes of can...

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...

An evolutionary perspective reveals why immune processes are an intricately interconnected with each other and with other biological processes within multicellular organisms. This web-like interconnectedness has important implications for medical interventions. Evolutionary considerations suggest that direct manipulation of molecules and processes...

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 indu...