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Evolution - Living Symbiotically with MicrobesAll things change in order to develop and expand. In biology, the theory of evolution explains that

Groups of organisms change with the passage of time, mainly as a result of natural selection, so that descendants differ morphologically and physiologically from their ancestors.

In layman’s terms, morphologically means “in appearance” and physiologically means “with regard to function.” Natural selection is the concept that

only the organisms best adapted to their environment tend to survive and transmit their genetic characters in increasing numbers to succeeding generations, while those less adapted tend to be eliminated.

Even in the most basic definition of the term, evolution implies that some type of change must occur. With regard to the scientific theory, it explains this change in purely genetic terms. Indeed, for simpler organisms (such as bacteria, fruit flies, or algae), this is the only change necessary for evolution to occur. However, in more complex systems (human beings, societies, nations, or the planet), changes can be genetic, behavioral, or, conceivably, can even relate to human consciousness.

It is valuable to investigate the evolutionary process as it relates to health. Based on this analysis, we can attempt to evaluate how our future might be affected. However, it would be beneficial for us to discuss a few key facts. Throughout history, man has had to contend with famine, war, natural disasters, and, of course, disease. Each one has served to act as a natural form of population control and, therefore, as a catalyst to the evolutionary process itself. For each new and successive challenge, man has been forced to use his ingenuity to overcome any obstacles before him. If unable to manipulate his external environment, he would have to adapt physiologically. In this way, man has been able to withstand the pressures of living on this planet and, as a result, to continue his existence. This is how the incredible process of natural selection works in its most apparent and practical application.

Just as man has had to adapt to his environment to ensure his survival, so have the multitude of other organisms inhabiting the planet alongside him. Animals, plants, and insects have all undergone their own unique evolutionary processes, as have microorganisms, including bacteria and viruses. Even these organisms, which are typically associated with human disease and death, must change and adapt to survive.

Adaptation, natural selection, mutationBut we must ask ourselves: are the organisms that cause human illness actually a threat to our existence, or are they simply different life-forms with which we must learn to coexist? Obviously, we can be as much of a nuisance to bacterial and viral microorganisms as they can be to us. Since they typically lack the machinery to exist and multiply independently, microorganisms require a host organism (such as a human, animal, insect, or plant) in which to dwell. When the host actually ends up attacking the microorganisms, these life forms must also adapt to their environment or risk being killed off. Both bacteria and viruses adapt by mutating, which enables them to evade detection more effectively. This is vital, as their surroundings may suddenly become saturated with a poisonous antibiotic or perhaps even get invaded by dangerous (to them) white blood cells. Very often, these organisms are placed under the most extreme and stressful conditions. At these times, they will respond by multiplying rapidly in a final attempt to survive, often killing off their host in the process.

On an evolutionary level, viral and bacterial organisms have played a crucial role in human existence. Without them, the human immune system would have had very little stimulus to develop, perhaps even weakening the human species as a whole. We cannot disregard these microorganismic life forms when contemplating our own evolution. They have been vital in helping us develop into the living beings we are today (as well as being our oldest ancestors, but that is another story).

Interestingly, humans have been playing a game of cat and mouse with microorganisms for decades, all in a futile attempt to eradicate them from the planet. Our efforts, however, have not only failed to remove them from our lives completely but have also led to the creation of superspecies that have successfully adapted to our weaponry. Even as we have succeeded in ridding ourselves of diseases like polio and smallpox, new forms of microorganisms have surfaced to take their place. The SARS-associated coronavirus (SARS-CoV) and the avian influenza (bird flu) viruses are two current examples; they are among the newest microorganisms to threaten human health. Human Influenza Virus is yet another—this virus is itself a rapidly mutating pathogen, and as such, we have been unable to control it effectively. As a result, a new flu vaccine must be developed and administered annually to combat emerging strains.

HIV, immune system, evolutionThe importance of these examples lies in illustrating a fundamental principle of human health. The virulence (strength) of an organism is not the only factor involved in our response to infection—that is, whether we’ll get sick or what our chance of survival is if we do. In fact, virulence may not even be the primary factor involved in illness at all. It is becoming increasingly evident that the environment in which an organism lives plays a crucial role in determining its outcome. Healthy individuals (those with strong and well-functioning immune systems) have the greatest ability to ward off illness and, in the process, become stronger with each successive exposure, as coming into contact with virulent microorganisms serves to strengthen their immunity.

We can see examples of this with every infection known to man. Take HIV, for instance; when homosexual men first started showing signs of disease in the latter part of the 1970s, the initial prognosis was of a sure and swift death. We now know, however, that it is possible to live for many years, and even thrive, despite being infected with HIV. Yes, it’s true that people still die from AIDS; nonetheless, we can all glean a glimmer of hope from people like Ervin “Magic” Johnson, who conducts his life healthily and productively even in the face of being HIV positive. Magic Johnson and others like him not only serve as inspirations to anyone diagnosed with HIV, but also remind us that our current views on health may no longer be adequate: we may need a new model.

Essentially, the message I would like to get across here is that as long as human beings inhabit the earth, there will be organisms that we must contend with; organisms that may compromise our health and even cause death in epidemic proportions. It would probably be wiser to strengthen our immune system or the environment in which these microorganisms must dwell, rather than solely relying on outside interventions to combat what are otherwise worthy life forms. By adopting optimal health practices, you will do more to ensure your survival and, subsequently, pass forth your genes than you will by doing nothing at all and leaving your health to chance.

ecomposing, bacteria, evolution, adaptationWe would be better served to appreciate all life-forms inhabiting our earth as not only worthy of their existence, but also as vital contributors to the evolution of this planet and, indeed, of life itself. The energetic configurations that form microorganisms serve many vital functions. They act as decomposers of other energy forms (for example, organic materials found in nature, as well as food in our digestive tracts), producers of vital gases and other biologically active substances, transporters of genes among different species, and, yes, even as a form of population control. Why, then, should we attempt to eliminate organisms that have such a high degree of functionality?

It does not make sense for us to attempt to eradicate any other life form, as we cannot be confident with our limited knowledge of what their functions might be. It seems logical, then, to accept all living forms as our cohabitants on this earth. Of course, we must always remain vigilant, as it would be foolish to allow an overgrowth of microorganisms to compromise our resources or health. However, despite a certain amount of individual risk, our species can certainly coexist symbiotically with all other life forms. In fact, it appears that we even need them to continue our own physical evolution. It would seem more practical to focus our attention on health-enhancing behaviors, those that enhance and revitalize our own energy, rather than on eradicating microorganisms.

Hurricane Katrina evacuationThe stark reality is that we must learn to coexist with many different species, some of which have yet to be discovered and perhaps even some that have not yet evolved. Some new species will likely be created by our own elaborate endeavors, particularly through genetic engineering (as with SARS-CoV-2) and the rampant misuse of antibiotics (superbugs). Please understand, however, that I do not deny the necessity of monitoring the dynamics of human-microbe interactions—it is essential. However, by practicing healthy habits, we stand the best chance of living symbiotically with all other life-forms, which is crucial, as we should not allow them the opportunity to eradicate us either.

Along with ever-evolving microorganisms, we will also have to contend with our fair share of natural disasters in the future, such as Hurricane Katrina, which devastated New Orleans in the autumn of 2005. What stood out the most for me from this tragedy was the overwhelmingly large number of sick and infirm people who were incapable of withdrawing from the city. Even though this scenario is a harsh reality of any emergency evacuation, I cannot help but feel that, as a population, we can consciously change the number of people needing ambulatory assistance. Here is a relevant statistic:

Approximately 50 percent of all deaths in this country are due to faulty lifestyle choices (lack of movement, poor diet, drugs, etc.).

If we could reduce this number by even 10 percent, disasters like Katrina might claim fewer lives.

Not only that, but in today’s volatile political environment, where the threat of terrorism and war looms constantly overhead, we will likely see the earth’s natural resources—particularly freshwater—become even scarcer.

We cannot be sure of where the human evolutionary path might lead us, so doesn’t it seem wise to prepare ourselves physically for any scenario that might eventually surface?

The best preparation would be to adopt healthy, life-enhancing habits: healthy diet, movement, rest, bodywork, mental balance, and toxin avoidance are the essential components to strengthen and boost your body completely. With optimal health, you will not only have a greater chance of surviving a major catastrophe, but more importantly, you will find that excellent health gives you a large degree of personal fulfillment and enhances your life significantly.

Life & DeathOne final point I would like to make is that if we wish to keep our views on health in perspective, as well as how health serves us, then we must acknowledge a simple fact: we are mortal beings. Although everyone is aware of the inevitability of death, many of us tend to see death as “bad” or undesirable. Death, however, is as important to life as life itself. Without it, we would not be able to support new life, whether human or otherwise, as our vital resources would become exhausted from uncontrolled population growth. The truth is that to defy death, we would have to defy the tendencies of the universe—particularly those that relate to the movement of energy, polarity, and rhythm, and, in fact, evolution itself.

The first law of thermodynamics states that energy can be neither created nor destroyed; it can only change forms. Further, as a result of the universe’s tendency toward polarity, very few things exist without their exact opposites. Birth and death, then, represent the two poles of one type of energetic formation: our physical bodies. We cannot escape this fundamental progression. As energetic life-forms, we must naturally submit to these universal forces. Birth, life, and death occur together as one single process; they are, shall we say, inseparable. As this process unfolds, it does so in a very distinct rhythmic pattern—seventy to ninety years in the human perception of time—yet nothing more than a brief moment, a spark, in the grander scale of the infinite universe.

We must accept death as a natural process. Although the physical body seems to appear and then disappear rapidly in a short wisp of time, we can rest assured that our energy remains in the universe forever. Major religions call this immortality. We are mortal beings, dependent on the physical laws of our physical world; however, we are immortal too—in spirit.

So embrace it; don’t fear death. Living your life in fear is not living at all. Not only will fearing death prevent you from experiencing all the richness life has to offer, but it will also lead you to make poor decisions regarding your health and well-being.

Life is precarious – there are truly a million ways to die. And even amid tens of thousands of years of evolution, the dangers have stayed the same. Violence, accidents, natural disasters, starvation – there are many ways for man to meet his end. One hazard that has evolved alongside humans is the pathogenic microorganism – the bug (germ). These micro-toxic invaders seek entry into our bodies, to take over our physiological systems for their gain, essentially the propagation of their colonies (species) through the use of our cellular resources.

But we are not sitting ducks. On the contrary, evolution has led to the development of the most efficient cellular fighting force the world has ever seen. The military might of this army executes day-in-and-day-out its prowess in keeping the human body safe and sound, despite the constant exposure to hostile invaders. This cellular soldiery is the human immune system, and it has a vast and varied genetic code that allows it to stay on top of all innovations in the pathogenic arsenal.

The immune system is complex and magnificent, and I wish to share its grand design with you here. In this article, I will explain the basics of immune system physiology, describe innate and adaptive immunity, and a few of the cells and immune factors that act as soldiers and weaponry of this legion. This article will also serve as a reference point for all future writings on immune function and how you can enhance yours. With that, I bring you the glorious human immune system.

Immune System Function

The immune system has the primary function of keeping the body free from invaders. These can include things like bacteria, viruses, and even cancer cells. Of course, it is impossible to keep invaders out completely, so when they do penetrate the body’s primary defenses, the immune system has cells that patrol the body and destroy any invading cells it encounters. Finally, the immune system keeps track of all invaders it comes into contact with. It creates an identification record so that if those pathogens are reencountered, the immune response kicks in to mobilize an active army to seek and destroy the intruders.

I particularly like to think of human immune function in terms of human military action – a metaphor that illustrates both basic and complex immunity effectively. By addressing the immune system and its function in this way, I believe it is easier to understand both its mechanism and rationale. With this analogy in mind, I think it is useful to think of the body as a kingdom, or homeland nation, or even an intricate fort. Essentially, it helps to view the body as something worth protecting, and therefore for the pathogen, also worth invading. Typically, pathogens seek entry to establish themselves in an environment conducive to their growth and propagation. What is good for them is generally not good for us, however, and so it is of utmost importance for the immune system, like a nation’s military, to be working at its highest potential.

Innate Immunity

Innate immunity is the non-specific immune system, which we can think of as our first line of defense. It includes our fortress walls, moats, and garrison soldiers. These are the barriers and forces that keep invaders out. It is non-specific in that it will work hard to keep out anything that looks foreign, regardless of type. It does not concern itself with whether it has seen the invader before – it is a keep-out-at-all-costs defense system.

First, we must discuss the walls which are things like skin, which acts as a primary barrier to microorganisms. Along with its impenetrable membrane, it has an acidic oil on its surface which renders it uninhabitable for many bacterial species. Mucous membranes in the nasal passages, mouth, and other orifices also act as a primary barrier to pathogens seeking entry. The acidic environment of the stomach makes it unsuitable for many bacterial and viral species.

If an invader makes it through the primary barriers, gaining entry into our blood circulation, respiratory, or other organ tissue, then our garrison foot soldiers come to the defense. These cells – known as phagocytes (neutrophils, macrophages, and natural killer (NK) cells) – essentially destroy invading organisms by swallowing them up (phagocytosis) or releasing chemicals, which disrupt cellular structural elements leaving the microorganism susceptible to bursting. Phagocytes can also induce inflammation and release chemicals that send signals to recruit another class of immune cells called lymphocytes to the site of infection.

Adaptive Response Immunity

Some invaders will find entry into the kingdom. The mechanisms evolved to evade the initial onslaught may include the secretion of bacterial toxins to impair protective functions of host barriers (like ciliary clearance function [hairlike sweeping] of the respiratory tract), biofilm formation, and evasion of immune recognition, among others. Regardless of the means used to gain entry, once in, the invaders can cause maximal damage. They will initially float around the body’s extracellular fluids like the blood, lymphatic, cerebrospinal (CSF), and pleural fluid, as well as in body cavities lined with serous (moisture-exuding) membranes.

Humoral Immune Response

Enter the humoral immune response: secreted antibodies, opsonins, and the complement system (which complements antibodies), surveilling the body fluids (humors) on a seek-and-destroy mission. When these reconnaissance satellites encounter a pathogen, they may directly kill it (complement system) as might a missile-wielding drone, coat it for recognition (opsonization) by destructive soldiers (phagocytes), or interfere (sabotage) with the chemical interactions required for the pathogen to infect or bind to other cells (antibodies).

The special forces are the elite soldiers on the battlefield, and for the human immune system, these are the lymphocytes of the adaptive or specific immune response. The B lymphocytes are responsible for the humoral immune reaction. They recognize foreign antigens – molecular markers that elicit an immune response – and respond by creating antibodies specific to that marker. As a result, they become the progenitor of specific B cells which will forever recognize one specific invader – a bacteria or virus, let’s say. They differentiate into memory and plasma B cells, which are like the intelligence and munitions departments of the armed forces.

Memory B cells are long-lasting lymphocytes (some lasting decades), which present the original recognition receptor of the parent for the specific pathogen and its antigen on their surface. They are one of several antigen-presenting cells (APC), along with macrophages and dendritic cells (DC). Their primary role is to act as long-term recognition of a pathogen it has seen before, and so these cells are responsible for what we call the secondary immune response. It is what gives us long-term immunity to previous invaders.

Plasma B cells, or effector B cells, are essentially antibody production plants. They produce large quantities of long-lived antibodies specific to the pathogenic antigen of its parent cell. The antibodies are released into the fluid system to circulate throughout the body. They act as surveillance reconnaissance drones keeping on the lookout for a future invasion by the original intruder.

Cell-mediated Immune Response

So, while B cells of the humoral system produce antibodies, which in turn circulate throughout the body in search of previously encountered antigens, they are only effective against free-floating pathogens. In other words, only pathogens moving about freely in the body’s fluids are at risk from circulating antibodies. But what happens when an invader makes it inside a cell, infecting it? If antibodies are helpless against these infiltrators, then is that the end of the fight? The answer is: “Absolutely not” – this is where cell-mediated immunity comes in.

The big guns of the cell-mediated immune response are T lymphocytes (cells). Other soldiers like macrophages and NK-cells also contribute to these reactions, but cytotoxic T cells are the assassins of the immune system while helper T cells the secret police. Cell-mediated immunity is the destruction of cells that have been infiltrated. This could happen from a bacteria or virus, but it can also be a cancer cell. Any cell that needs to be eliminated will be paid a visit by one of these soldiers.

In the case of the cytotoxic T cell, the visit is paid direct. These T cells directly kill the infected or cancerous cells by poking holes into their membranes and inserting enzymes, like grenades or other IEDs, which ultimately destroy the infected cell. Like assassins, cytotoxic T cells go in, create a vulnerability, and then exploit it.

Helper T cells, on the other hand, act like the police by surveilling the body. When they encounter foreign antigens, they also act in a specific manner, like the B lymphocytes, specific to only one antigen. When activated, helper T cells differentiate into memory T cells – which are long-lasting, providing long-term immunity – and effector cells. Effector T cells are the alarm system, which sends out signals to draw in even more soldiers to the area. They also play a role in activating B cells to secrete antibodies and proliferate into memory B cells.

Inflammation, Hypersensitivity, and Autoimmunity

A healthy, robust immune system is paramount for keeping our bodies free from invaders. However, it can also be too robust. Three immune responses that can go haywire and lead to destruction and even death are inflammation, hypersensitivity, and autoimmunity.

Inflammation is a normal, healthy, and abundant immune response to injury, infection, and tissue damage; it is the engagement of the military on the battlefield. It is characterized by heat, redness, swelling, and pain at the site of injury or infection. Inflammation serves to eliminate pathogens, clear debris, and initiate tissue repair, and it recruits soldiers from both the innate and adaptive immune responses (like neutrophils and macrophages, as well as B and T lymphocytes).

A fundamental part of the inflammatory response is cytokine release, whereby signaling molecules act as messengers to initiate, amplify, and regulate the inflammatory process. It contributes to the body’s defense against infection and injury. Dysregulation of cytokine signaling can lead to chronic inflammation and contribute to the pathogenesis of various inflammatory diseases.

Hypersensitivity refers to an exaggerated or inappropriate immune response to harmless substances, known as allergens. There are four types of hypersensitivity reactions (Type I to Type IV), each involving different mechanisms and immune components. An example of hypersensitivity is allergic rhinitis (hay fever), where exposure to pollen triggers an exaggerated immune response, leading to symptoms such as sneezing, itching, and nasal congestion.

Systemic lupus erythematosus (SLE), is an autoimmune disease in which the immune system attacks its own tissues, causing widespread inflammation and tissue damage in the affected organs

Autoimmunity occurs when the immune system mistakenly targets and attacks healthy tissues and cells, leading to tissue damage and dysfunction. Autoimmune diseases can affect various organs and systems, and they are characterized by chronic inflammation and immune-mediated damage. An example of autoimmunity is rheumatoid arthritis, where the immune system attacks the joints, causing inflammation, pain, and joint damage over time.

Each process can and does have significant implications for health and disease. The cytokine storm was a hallmark of severe COVID-19 infection and has been recognized as a major cause of mortality among COVID-19 patients. Hypersensitivity may be another important mechanism involved in severe cases of COVID-19.

Epilogue

As you can see, the complexity of the human immune system is vast, and its potential to adapt to specific invaders…infinite. That makes the immune system a veritable guarantor of survival and a generator of evolution for the human species. What I have given you here is a sound overview of immunity – its soldiers, its systems, and its processes. As I have said above, I will refer back to this article often regarding other topics on immunology and health. I have attempted to organize the information and make it easily scannable to gather information quickly, and I have provided links to further reading and study. The next question I want to ask is: what can be done to enhance the immune system to increase health and wellness? Stay tuned.

Copyright © 2013 Dr. Nick Campos - All Rights Reserved.