EVOLUTIONARY MEDICINE

Ecology and adaptations - Evolutionary medicine (with a focus on particular disease(s)/treatment(s) that are evolutionarily informed

Ecology and adaptations - Evolutionary medicine

Introduction

Medicine is a science whose objective is to develop skills and knowledge to diagnose, prevent, alleviate and cure diseases. Historically, medicine has focused primarily on the causes and symptoms of disease to carry out its objectives, but in general, one can say that so far medicine has forgotten the "why" evolution of the characters and diseases human, a feature which would improve the understanding and treatment of disease. Not long ago is emerging that has been called evolutionary or Darwinian medicine, which seeks to provide an evolutionary approach to this science. Since man, like all other organisms is the result of evolutionary processes that occurred in relation to the environment and selective pressures that surrounded our ancestors and where we live now, evolutionary thinking has begun to be present in modern medicine and to be regarded by many physicians. It is perhaps in infectious diseases at the genetic and non-infectious degenerative lesions (especially those related to aging and cancer), where the evolutionary approach promises a much greater understanding and therefore treatment of these diseases. Here are some examples in which evolutionary thinking has been very beneficial to understand the disease. (Pyles, 2007, PP: 2:4)

Evolutionary explanations of some diseases

In diseases caused by heterozygous advantage, certain alleles may represent an evolutionary advantage to heterozygous carriers, but clearly are harmful in homozygotes. The classic example is sickle cell anemia, which protects against severe forms of malaria. Heterozygous for the hemoglobin S allele have a high capacity for phagocytosis of red blood cells infected with the "ring" of malaria parasites (especially Plasmodium falciparum). In fact, these carriers have more than 90% protection against severe forms of malaria. As malaria infection can be fatal, natural selection has maintained heterozygous forms of hemoglobin S allele in large areas of Africa, although homozygous individuals contract a serious disease such as sickle cell anemia. Other adaptations have appeared in red blood cells against malaria infection such as deficiencies in glucose-6-phosphate dehydrogenase deficiency in pyruvate kinase, alpha-thalassemia, hemoglobin C disease and hemoglobin E disease). (Slatkin, 2008 PP: 477-485)

Another hypothesis to explain some diseases also considers developmental aspects. It starts with the idea that in the past humans were adapted to other habitats (e.g. the savannah of Africa.) Over time, our environments, both physical and cultural change faster than the evolving capacities of allelic exchange, and emerging diseases in this era. Among them would be diabetes, cardiovascular disease and hemochromatosis. For example, the gene mutation that causes hemochromatosis C282Y might occur as an adaptation that occurred when human prehistoric hunter went from a diet rich in meat, grain diet (the result of agriculture) and short on meat, causing anemias. Since both homo-and heterozygous mutants in the gene C282Y have large reserves of iron, this is a mechanism that might be useful in the Neolithic, especially in women during the breeding season, but now, where diet rich in meat , this mutation may not be advantageous. (Fraser, et al. 2007, PP: 17441-17446)

Infectious Diseases

Today we tend to think that ...