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Evolutionary Medicine www.AssignmentPoint.com www.AssignmentPoint.com Evolutionary medicine or Darwinian medicine is the application of modern evolutionary theory to understanding health and disease. The goal of evolutionary medicine is to understand why people get sick, not simply how they get sick. Modern medical research and practice has focused on the molecular and physiological mechanisms underlying health and disease, while evolutionary medicine focuses on the question of why evolution has shaped these mechanisms in ways that may leave us susceptible to disease. The evolutionary approach has driven important advances in our understanding of cancer, autoimmune disease and anatomy. Medical schools have been slower to integrate evolutionary approaches because of limitations on what can be added to existing medical curricula. Human adaptations Adaptation works within constraints, makes compromises and tradeoffs, and occurs in the context of different forms of competition. Constraints Adaptations can only occur if they are evolvable. Some adaptations which would prevent ill health are therefore not possible. DNA cannot be totally prevented from undergoing somatic replication corruption; this has meant that cancer, which is caused by somatic mutations, has not (so far) been completely eliminated by natural selection. Humans cannot biosynthesize Vitamin C, and so risk scurvy, Vitamin C deficiency disease, if dietary intake of the vitamin is insufficient. www.AssignmentPoint.com Retinal neurons and their axon output have evolved to be inside the layer of retinal pigment cells. This creates a constraint on the evolution of the visual system such that the optic nerve is forced to exit the retina through a point called the optic disc. This in turn creates a blind spot. More importantly, it makes vision vulnerable to increased pressure within the eye (glaucoma) since this cups and damages the optic nerve at this point, resulting in impaired vision. Other constraints occur as the byproduct of adaptive innovations. “Diseases of civilization” Humans evolved to live as simple hunter-gatherers in small tribal bands, a very different way of life and environment compared to that faced by contemporary humans. This change makes present humans vulnerable to a number of health problems, termed “diseases of civilization” and “diseases of affluence”. Humans were designed to live off of the land, and take advantage of the resources that were readily available to them. They were designed for the stone-age, and the environments of today bring about many disease causing ailments, that may or may not be deadly. “Modern environments may cause many diseases-for example, deficiency syndromes such as scurvy and rickets”. Diet In contrast to the diet of early hunter-gatherers, the modern Western diet often contains high quantities of fat, salt, and simple carbohydrates, which include refined sugars and flours. These create health problems. Trans fat health risks Dental caries www.AssignmentPoint.com High GI foods Modern diet based on "common wisdom" regarding diets in the paleolithic era Life expectancy Examples of aging-associated diseases are atherosclerosis and cardiovascular disease, cancer, arthritis, cataracts, osteoporosis, type 2 diabetes, hypertension and Alzheimer's disease. The incidence of all of these diseases increases rapidly with aging (increases exponentially with age, in the case of cancer). Of the roughly 150,000 people who die each day across the globe, about two thirds—100,000 per day—die of age-related causes. In industrialized nations, the proportion is much higher, reaching 90%. Exercise Many contemporary humans engage in little physical exercise compared to the physically active lifestyles ancestral hunter-gatherers. It has been proposed that since prolonged periods of inactivity would have only occurred in early humans following illness or injury that it provides a cue for the body to engage in lifepreserving metabolic and stress related responses such as inflammation that are now the cause of many chronic diseases. Cleanliness Contemporary humans - due to medical treatment, frequent washing of clothing and the body, and improved sanitation - are mostly free of parasites, particularly intestinal ones. This causes problems in the proper development of the immune www.AssignmentPoint.com system although hygiene can be very important when it comes to maintaining good health. The hygiene hypothesis says that many modern humans are not exposed to microorganisms that have evolved in establishing the immune system as they should be. “Microorganisms and macroorganisms such as helminths from mud, animals, and feces play a critical role in driving immunoregulation’. They play a crucial role in building and training immune functions to fight off and repel some diseases, and protect against excessive inflammation which has been implicated in several diseases (such as recent evidence for Alzheimer's Disease). www.AssignmentPoint.com