The topic of Evolution has been a controversial topic since the day it came to light. People believe that one’s faith can be denatured like a protein if they begin to believe in the science of evolution. Others believe that there could not possibly be a greater being when we have knowledge of the science behind certain wonders such as this very subject. The truth is: one cannot even begin to understand science if evolution is not involved. Religion being the explanation instead of the other way around. Why have such a beautiful and intricate knitting of ideas as God, if it did not serve a greater purpose? and what greater purpose than for the sake of humans to dwell on earth and learn to find their way back home in the celestial kingdom? In this paper, we explore one of the most frustrating, yet fascinating proof of the phenomenon we know as evolution. We will discuss certain microbes’ ability to evolve to bypass antibiotics and how they are able to do it.
We first will discuss the appeal and need to survive in non-living matter, which is evident in every living creature. One does not need to look far to find this to be true. We are reminded of this point by merely turning on the television and watching animal planet, the discovery channel or if we spend the time watching these shows long enough to hear our stomach rumble. The rumble and discomfort we hear, and feel is a reminder to give our bodies the energy it needs to continue living. Survival is an instinct that is embedded in our minds even if we are not aware of it.
However, having the desire to survive, be alive, and pass on our genes is not limited to the living. A less obvious object of topic is a virus. In the article written by Luis P. Villareal titled Are Viruses Alive? we note an interesting point he has made. Villareal reports the frustration of categorizing viruses as nonliving. He mentions that even though this is an accurate categorization, it has lead scientists and researchers to ignore the study of evolution in viruses until recently. He happily mentions that researchers are have started to pay attention to viruses and the role they play in the foundations of life. It is helpful to remember and keep in mind that bacteria are categorized as non-living organisms for a couple reasons. The main reason being that they are incapable of reproducing on their own. They require host machinery in order to complete the task that defines an organism as living.
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Viruses depend on host machinery for nucleic acid synthesis, protein synthesis, and other biochemical activities such as processing and transport, and anything else which would allow for the virus to replicate. Villareal describes viruses as “metabolically active sacks” because they contain genetic material but is not alive. He compares viruses to a seed because a seed though it is not alive, has the potential to become something with life, and can be destroyed. He says that a virus is more comparable to a seed than a rock or a cell. As previously mentioned, viruses have a genetic code which dictates the action to multiply and spread its genetic material because even for them, they must change or meet their demise.
This demise being eradication as we have achieved with the smallpox vaccine and are slowly getting close with the polio virus. In a world where competition for continuing to exist is a priority, we can understand why it is that change is essential in a “metabolically active sack” as Villareal put it. A perfect example of this phenomenon is seen in studying the influenza virus. Antigenic drift and antigenic shift explain the how of the question. Both evolutionary mechanisms are often observed in the influenza virus. We will first address antigenic drift which are gradual and small changes in the genes of the virus.
These changes occur continuously and over large periods of time as the viruses undergo replication. The product of these gradual changes are viruses which are closely related. The Centers for Disease Control and Prevention says that these viruses which are closely related may have the potential to be recognized by the immune system because they share similar or the same antigenic properties. Therefore, if an immune system has previously been exposed to a closely related virus, it will respond to the ones that have undergone drift. Sometimes there are small changes that result in larger phylogenetic changes that make the influenza virus so different from one another that it results in the memory immune cell response not able to recognize the virus.
This is because it has now evolved into a new unrecognizable antigen in the body. This is the reason for why there is a need for a new vaccine composition each year. A frustrating point in the evidence of evolution, antigenic shift. Antigenic shift is similar but much more extreme and quicker. To understand this change, we must know that the influenza virus contains two glycoproteins in its membrane, hemagglutinin and neuraminidase. Hemagglutinin aids in anchoring the virus to the host cell and neuraminidase aids in the release of the virus’ genetic content into the host.
The center for disease control says that this shift is not only abrupt, but it is the means for dramatic change in the influenza A viruses which allows them to not be recognizable by the immune system. This is because there will be a new hemagglutinin and/or hemagglutinin and neuraminidase protein combination in the capsule of the virus thus resulting in a completely new subtype of virus capable of infecting humans and non-human animals. Now that we have seen how a non-living object is able to acquire an ability to spread and survive, how much more then must a living organism have a need to survive?
As mentioned previously, we were able to eradicate smallpox to survive as humans. We have achieved this great feat through passive immunity thanks to scientific intervention. However, because our own genome has instructions on survival, we have an immune system which works wonderfully in all immunocompetent beings. We can resist certain pathogens to an extent because of our third line of defense, our adaptive immunity. We acquire this active immunity when we first become exposed to a pathogen.
Through a series of communication and destruction of pathogens, our bodies are able to create a memory of the microbe so that if we were to become infected again, our immune system can act accordingly in order to get rid of the pathogen causing an obstruction in our goal to maintain healthy. We remember our history lessons about the pandemic known as the Black Death or the Black Plague. This pandemic occurred in the 1300s and it made people believe that it would be the end of the world. How is it that we survived as a race? There is an article written for NBC news by Seth Borenstein titled Deadly Black Plague Hasn’t Changed, But We Have. In the article, he explains that the microbe which cause the deadly disease has not undergone much change.
Of course, as we are on the topic of evolution, we know that it has undergone change, but in relative terms, it is not great change. In fact, the change in the gram-negative bacterium is not the cause for the great decrease in infections. In a study conducted in the researchers sequenced the genome of Y. pestis. They recorded the genome length of the strain CO92 as 4.65 mb, with three plasmids of 96.2 kb, 70.3 kb, and 9.6 kb. The study produced an observation by the Daily News. They noted that out of the large genome, there had only been a few dozen changes in the building blocks of DNA. They reported that the microbe similar to the one that caused the great pandemic known as the bubonic plague and that we as a human race were the ones that underwent a greater change resulting in resistance to the disease.
The figure displays the phylogeny of Yersinia pestis and the evolutionary changes it underwent in order to become a pathogenic microbe and cause three pandemics, the third one being the black plague. As previously mentioned, today, we do not see that much difference in the genome of the bacteria that caused a near wipe-out of humans. Although it took many years and deaths to achieve this, it is thanks to the power of natural selection that we can be here today. The forces of evolution allowed us to adapt or defend ourselves from an environment that attacked us. Evolution in organisms such as humans or non-human animals, like a finch for example, can be studied with great patience and much observance. However, great patience and much observance is not necessary for a microbe, which brings us to our following point.
When evolution is faster, and it is easier to adapt, it becomes a weapon. In the book The Origin of Species: The Beak of the Finch written by Jonathan Weiner, he quotes Charles Darwin by writing “ Competition is also a silent race for the last food on a desert island where the competitors never fight one another and the only sound of battle is the occasional crack of a seed.” Darwin spoke about something he called “the smallest grain in the balance” which is the slightest change or variation in a beak size or shape that will determine death or life for a finch. Therefore, the battle of survival was near silent. For a bacterium, however, the battle of survival is in every way completely silent.
To paint a picture, we can look at penicillin resistant gram-negative bacterium. It is important to note that penicillin is just one of many antibiotics which bacteria are growing a resistance to. It is a bactericidal antibiotic which weakens the cell wall by targeting the enzymes which cross-link the peptidoglycan layer in the wall. Gram-negative bacteria are not as susceptible as gram-positive because the latter do not have an outer membrane which serves as protection for their peptidoglycan layer. The only way for penicillin to pass through the outer membrane is through porin channels. There are several mechanisms for these bacteria to acquire an immunity, and we look at three of them; Starting with restricting transport of penicillin.
Dr. Katy Metzler, a college instructor, explains that some resistant strains may have mutations which cause them to produce either less porins or ones that are smaller. This results in less penetration of penicillin through the membrane into the peptidoglycan layer which is where in needs to be in order to achieve its purpose. A second way that resistance can occur is through modification of target molecules which are called penicillin-binding proteins. Resistant strains may often have mutated penicillin-binding proteins that penicillin can no longer bind to. In all cases of resistance, it is possible for homologous transformation to occur.
This is when a bacterium dies and leaves free-floating DNA. A similar bacterium near the vicinity may uptake the naked DNA with the resistance gene and intergrade it into its own chromosome and acquire the immunity. The last mechanism of resistance to address is production of beta lactamases. Dr. Metzler also explains that a third method that gram-negative bacteria use for resistance is the production of enzymes, known as beta-lactamases, in order to break down penicillin to render it ineffective. Penicillin is categorized as a beta-lactam antibiotic which simply means that the antibiotic contains a beta-lactam ring in its structure. Beta-lactamases cleave the ring which is essential for the breakdown of peptidoglycan.
In discussing these three mechanisms of resistance, we can couple that with one of the most common sexually transmitted infections in the world, gonorrhea, to put it into perspective. Gonorrhea is one of the many infections growing a resistance against penicillin. The bacterium which is responsible for this infection is Neisseria gonorrhea, a gram-negative bacterium. As we pair up an infection that is a worldwide, growing problem with another equally threatening issue, we may consider that the ability for these microbes to evolve ever so rapidly, is a product of evolution, not an unexplained happening.
There is currently much research being conducted in order to try and understand more mechanisms of resistance as well as trends and or decreased susceptibility to certain antibiotics, including penicillin. For example, in the published article, “Antimicrobial resistance to Neisseria gonorrhoeae in Canada: 2009-2013” by I Martinn, P Sawatzky, G Liu, and MR Mulvey, they concluded that susceptibility is decreasing, and that resistance is slowly emerging.
The study was conducted in 2009 and it lasted for about four years. According to the figure above, the researchers noted that 36.1% of the N. gonorrhoeae isolates were diagnosed by culture as resistant in the year 2013. The study was done by culturing 3,195 isolates of N. gonorrhoeae in public health laboratories in Canada. Out of the 3,195 isolates, 1,153 were said to have decreased susceptibility.
Failing to understand the purpose and the events of evolution can be detrimental to any scientist as Dr. Jeremy Spiegel tells in his article titled “Why We Must Understand Evolution”. He says, expresses that without an understanding of evolution, we can only ever reach a “surface quality” of comprehension. Dr. Spiegel then gives the perspective of a physician that may not consider evolution in their practice as a doctor. He says that one can better understand how the body of one’s patient might work, especially when advising and cautioning them against the abuse of antibiotics or in taking the prescribed amount all the way through as they are meant to do.
He makes a bold statement that it is those scientists who understand and appreciate the study of biological evolution that are able to provide the best chance of “fresh thinking” to the treatment of diseases. In the same article, Dr. Speigel compliments his point by quoting Dr. Stephen Stearns at Yale. he quotes “Unless you were thinking about coevolution of humans and their gut flora, you never would have thought you could treat an autoimmune disease by making the immune system think the body is inhabited by parasites.’ (quoted in Medical News Today 1/27/10). Dr. Speigel then reports that the example given by Dr. Stearns is simply one of many evidences for the truth of evolution through natural selection which occurs today in tiny living organisms to larger ones and even viruses.
As we continue to search for answers and understanding evolution and unfolding the mysteries of life, we can hopefully come to an agreement in the future. The agreement being that the foundations of any scientific subject cannot be understood if we do not accept evolution. It would be as Dr. Spiegel explained, we would only be able to understand the surface qualities in the subjects we study, and what an absolute obstacle in our learning that would be.
If the religious community that doesn’t accept evolution believes that we were come to earth to achieve a body and reach a goal of perfection, then is change not needed in order to become something different than what we started as? Is the purpose of coming to earth not evolving to transform ourselves into a greater being? Though it may be hard to explain exactly how evolution fits into The Creation, two things are for certain: first and foremost, we were made in the image of God and second, we live in a world that evolves for survival. William E. Evenson, in an evolution packet he comprised titled “Evolution and the Origin of man” he explains that having such differences in opinion and belief should never turn us one against the other.
He says that Christ taught kindness, and patience. We may not find the answers to everything we question in this life; but as we discover and are allowed to learn more truths, we may put the puzzle pieces together and knit both understandings of God’s purpose for us and the scientific method He provided for us to make it back to His presence. For now, it is enough to know that we can move toward that light as we continue to study and ponder the mysteries of our Creator.
