Evolutionary medicine and human health secrets

Evolutionary medicine and human health secrets
Why cancer exists? Or, more generally, why we get sick? Not ” how ” – it handles medical research and practice that unravel the molecular mechanisms and physiological underlie health and disease. A more difficult question is ” why” people get sick? – Why evolution has structured these mechanisms in a way that makes us vulnerable to disease?

Why are diseases for which there is pain, there mental illness, why the human body has the power to survive the onslaught of thousands of pathogens and yet falls prey to so many diseases? We are on the playing field – or the battlefield – of a new and fascinating science: evolutionary medicine or darwinian medicine, as it is called, which starts from the theory of evolution to understand the concepts of health and illness.

This new approach helped scientists to progress much in understanding phenomena such as the development of antibiotic resistance, autoimmune diseases, cancer, various psychiatric disorders. From the perspective of evolution, they are explained by the existence of structures and adaptive mechanisms developed by natural selection; they have remained in the human until today, but out of their original context – for modern human life no longer resembles its animals ancestors – dress today issues that we call pathological. Complicated? You’ll better understand the examples in the article.

Darwinian medicine is still a subject little known, frail represented in research, with a small number of followers. But it is one of the most interesting new approaches to medical science – one that digs much deeper, goes to the root of many different diseases, trying to unravel the evolutionary origin in the very becoming of human beings. Without substituting contemporary medical approach, without claiming to be an alternative to conventional medicine, it can provide additional look, a profound increment of current medical knowledge. Following this enrichment of theoretical knowledge, will come practical benefits too: new preventive recommendations related to health and new therapies.

Among the supporters of this new vision is: Paul Davies (from Arizona State University) and Charles Lineweaver from the Australian National University, the promoters of a new theory of cancer, evolutionary perspective; Randolph M. Nesse and George C. Williams, authors of one of the few books in the field yet – Why We Get Sick – The New Science of Darwinian Medicine, which appeared in 1996, was one of the first works that explained in detail this new vision of health and disease.

“Why exists, in the human body, so wonderfully designed, thousands of defects and weaknesses that make us vulnerable to disease?” As Nesse and Williams authors begin their first chapter – entitled exciting ” Disease mystery ” – in their book. With a dizzying physiologycomplex , admirably adapted to cope with a huge number of problems, survivable and getting them on foot – from infection with thousand of pathogenic kinds to fractures or injuries to internal organs – the human body however, have numerous vulnerabilities, manifested by many diseases that pose. Hard to understand this paradox, which the authors call ” the great mystery of medicine “. And yet, they say, an evolutionary perspective turns this mystery into a series of questions that can be answered.

A evolution strategy: the compromise

One of the key points is the understanding that evolution does not make things perfect – far from it. The human body is a collection of compromises. Many anatomical features amaze us by their apparent perfection – Human hands are capable of extraordinary things! – While others are perplexing us by the fact that seem ” bad thinked ” if the machinery of the human body was designed by a designer, one very incompetent would have thought, for example, to cross-pharynx digestive track with the respiratory and afterwards try to repair the stupid inventing a protective mechanism (apparently a complication in addition) that the airway is closed whenever you swallow a mouthful, for it not to enter the trachea instead go through the esophagus. (And, as we know, this mechanism fails quite often, as we choked with food.) Can give other examples, all showing that, although not “someones” work but the result of a natural process of evolution led by natural selection, the body hides , however, many compromise solutions, expression of middle way adopted by evolution to reconcile each with very different requirements.

An example often quoted is the radius bone of the forearm, which often fracture; so-called Colles fracture, distal portion (from the hand) of this bone is one of the most common types of fractures. Why did not evolution has endowed us with a radius bone thicker, denser, more resistant? Because he favored in the same time the increasing of complexity of the hand functions. The human hand is exceptionally skillful in the state of hands of any other primate species can not do, but wondrous skill has its cost: the radius bone composition is not very robust, which predisposes to fracture.

That means the evolutionary compromise: not achieve perfection, but be optimized in such a way as to satisfy several requirements simultaneously, each in the broadest sense.

For what is fever good?

Another key concept of evolutionary medicine: some symptoms of the disease – though unpleasant – are useful, because they are, in reality, the body defenses.

In this vision, fever is a defense mechanism; Immune system works better at higher temperatures, fighting efficiently against infection. That does not mean you shouldn’t use at all antipyretic (fever lowering); they can be useful when body temperature threatens to become dangerously high (especially when the body’s regulatory mechanisms are not yet well developed, as in the case of young children), or when fever causes increased discomfort. But this theory explains why, when we have only a trivial virosis, we should not panic when fe face a 37.7 fever and hurry to take a handful of pills to decrease by one degree.

Likewise, the cough is a defense mechanism that evolved to clean the lungs, bronchi and trachea of mircoorganisms pathogen; embedded in mucous secretions, these microorganisms get through coughing, the pharynx, where they are swallowed, ending in the stomach, where they are destroyed by the strong gastric acid juice.

Diarrhea can also be a defense mechanism: it is a means by which the body eliminates from digestive tract a large amounts of pathogen orgasims, thereby hastening recovery. Although further studies are needed to show when it’s right and when it’s better to take antidiarrheal medications, depending on the disease that it is, some comparative studies have shown that in some cases, medications can do more harm than good ; For example, if is a Shigella infection (a bacterium that causes severe diarrhea) untreated patients recovered faster than those treated with an anti-diarrheal medication (Lomotil).
Pain itself is a defense mechanism that often keep us from worse: the pain of an injured member prevents us to overburden it (because the overuse can hinder tissue repair and recovery functions).

If we know to defend ourselves so well, why are we still get sick so often? There are several reasons why the world is still full of the most varied diseases.

One of the reasons why there are so many infectious diseases, despite the fact that the human body has defense mechanisms so complex is that pathogens evolve too, we are in a continuous ” arms race ” in which pathogens and hosts that infects (including humans) are continuously adapt and respond to the threats from one anothers. This explains, among other things, the emergence of antibiotic resistance in bacteria, one of the major problems of the contemporary world.

Whenever there is a bacterial strain resistant to a particular antibiotic which, until recently, could be defeated, means that bacteria have scored a point, won a battle. But in other situations, wins the human hosts of bacteria: people have become more resistant to certain microorganisms than they were in the past. For instance, it is believed that Europeans have become more resistant to plague, after dreadful epidemics in the past, were down much of the continent’s population. Similarly, scientists believe that over 95% of the world presents today, immunity to leprosy, a disease that causes victims in Antiquity and the Middle Ages.

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