Dr. Mina’s presentation from a couple weeks ago gave the class a look into the many controversies surrounding the administration of vaccines. With his studies revealing that live-attenuated vaccines correlating with a greater susceptibility to upper respiratory tract infections, the dilemma becomes more complicated in regards to whether or not to let this information influence people’s thinking on what is strongly accepted by the medical and scientific communities as recommended practice. Although there have been many controversies related to vaccines throughout history, the most recent and relevant trigger for the modern anti-vaccine movement is generally considered be a study by Andrew Wakefield in a 1998 issue of the UK’s The Lancet that the MMR shot (used to inoculate against measles, mumps and rubella) caused colitis and autism. This resulted in a widespread abandonment of vaccination in the UK and Ireland, as well as significant influence on public perception of vaccines. The study has since been very publicly declared fraudulent (due to manipulation of evidence and other forms of ethical misconduct), with heavy scientific backing from multiple subsequent studies that concluded that there was no significant evidence to support Wakefield’s conclusion.

A recent article in the Huffington Post by Jennifer Raff, a postdoctoral fellow at the University of Texas with a Ph.D. in genetics and anthropology, addresses those parents who still remain seduced by the arguments of the anti-vaccine community, primarily by utilizing a wealth of scientific evidence to back up every single one of her claims both against the anti-vaccine movement and in support of vaccination in general. By linking her words to many different scientific publications, Raff provides readers with concrete evidence to counter several claims made by the anti-vaccine movement, including papers that negate the idea that measles, chicken pox, influenza, and whooping cough are not dangerous or deadly, that natural infection is a better vaccination, that side effects are not well known, or that vaccines cannot be trusted for a whole host of reasons. On the flip side, she also provides evidence for how vaccines are tested with great scrutiny for effectiveness and safety, and most importantly, encourages people to do their research before subscribing to a mentality that is literally killing children.

Evolution is a dynamic, interactive process that occurs constantly in nature, however, in a sense, humans have had disproportionate influence on evolution of other species thanks to the development of technology that allows us to achieve effects that animals in nature could not have accomplished. I think this is a very interesting article because we have read about how human interactions with the environment have changed pathogen transmission patterns in class, and this article provides more evidence that we might not be aware of.

12,000 years ago, domestication of wolves into dogs. Humans have domesticated all kinds of animals. Now days, the industrial, massive way humans fish is causing marine species to evolve to reproduce at younger ages and smaller sizes in order to keep passing on their genes. More specifically, cod, which have been overfished for decades off New England and the Canadian Maritime Provinces, have begun reproducing at younger ages and smaller sizes. Other species that have been observed to shower similar changes are bighorn sheep, caribou and ginseng plants. The shift in reproductive pattern improves the chances of reproducing before being killed, which gives those animals a short-term survival advantage. But it is harmful for the them in the long run, according to Paul Paquet, an environmental scientist at the University of Calgary, because the smaller, younger offsprings are not as strong and healthy as the older and bigger ones. Consequently, they are less likely to survive on their own. He refers to this phenomenon as “forced evolution”. As a result, Maine has passed legislation to protect lobsters and other common fish species from being hunted at a young age.

In addition, climate and landscape change have altered animal and plantation’s living environment beyond our estimation. For example, the development of highways and deforestation have physically limited the habitats of many wild animals and decreased their offsping’s diversity, which is detrimental for them in the long run. Furthermore, as a result of climate change, plantations shift their timing of bloom or move to a higher altitude in order to survive and reproduce.

The introduction of apples to North America in the 17^th century led some fruit flies that had specialized on hawthorn fruit to branch out to apples instead. By the mid-1800s, the branched out flies have completely separated to form its own species. Further down the stream, that has encouraged modification of parasitic wasps that feed on those flies.

When we read about a specific study on a specific pathogen, the human impact on nature does not seem to be too detrimental. However, when we look at the bigger picture that include all aspects of ecosystem, humans have greatly altered the way animals and plants survive and reproduce in nature.

Reference:

Dean, C. (2009, February 10). Seeing the Risks of Humanity’s Hand in Species Evolution. The New York Times. Retrieved from http://www.nytimes.com/2009/02/10/science/10humans.html

Summary:

Genetic Signature of Bacterial Pathogen Adaptation During Chronic Pulmonary Infection

            The main point of this article was to review and summarize the research project done by another group of scientists. These scientists were trying to find out about how the bacteria in patients with respiratory infections evolve within the person’s body over time. For instance, do the bacteria just simply clone themselves? Are they under selection pressures created by the environment of the human lungs? What is most exciting about this paper is that learning about how the bacteria that infect these kind of patients evolve could help develop new and better treatments to treat respiratory infections. Perhaps a regiment more like HIV is appropriate for example since the bacteria that infect these patients evolve and diversify as well.

The scientists looked at the bacteria in sputum samples taken from five patients with cystic fibrosis. They “sequenced pooled population DNA at a very high depth of coverage.” This allowed for an increase in detection of allele frequencies with less cost. One of the patients had whole bacterial genome sequencing, and the other four had only certain colonies sequenced.  It was found that “the majority of mutations were polymorphic.” Other indicators made it clear that the bacteria were under selective pressure that diversified them and created a state of heterogeneity.

The implications of this study are vast because they could greatly impact how we treat respiratory infections. It will probably change the drug regiments of these patients and maybe even completely new drugs will be made and distributed.

https://classes.emory.edu/webapps/portal/frameset.jsp?tab_group=courses&url=%2Fwebapps%2Fblackboard%2Fexecute%2Fcontent%2Ffile%3Fcmd%3Dview%26content_id%3D_2212739_1%26course_id%3D_71228_1%26framesetWrapped%3Dtrue

Although it was awhile ago, the discussion we had about birth in class stuck with me. As members of our cultural society, it’s difficult to differentiate between what’s actually true and what we think is true because of culture. In class, someone mentioned breech babies and how that position necessitated a cesarean section – but it doesn’t. Health and medicine in general have become very medicalized. Normal development processes like  menopause are now considered “conditions.”

This article provides a concise overview of why cesarean section births are on the rise. In class, Nelle had provided an example of how cesarean sections weren’t always the best option. The pressure involved in passing through the birth canal actually helps remove amniotic fluid from the baby’s lungs. Therefore, when a baby is delivered surgically, he or she may go on to develop issues like asthma and other respiratory challenges – all because of the manner in which he or she was born.

When researching the other benefits to a vaginal delivery, I came across one noteworthy example. Throughout the semester, we have talked about gut microflora and its influence on an individual’s health. Well, there’s evidence that supports the idea of a cesarean section  birth may stunting development of gut microflora. From other readings, we know that gut microflora influences digestion, metabolism, cardiovascular health and more. Additionally, babies born vaginally had gut microflora similar to that of their mother’s, while babies born by cesarean section had gut microflora similar to the bacterial colonies found on skin surfaces. I’m sure there are numerous other effects of delivery mode on both the mother and baby’s health outcomes. I think it’s important to be informed with evidence-based research, primarily because as we saw in class, we are all dramatically influenced by culture.

Here are links to the two articles I found:
1. http://journals.lww.com/jpgn/Abstract/1999/01000/Fecal_Microflora_in_Healthy_Infants_Born_by.7.aspx
2. http://www.pnas.org/content/107/26/11971.short

I finally got around to finding the paper on human pheromones. I didn’t get the exact paper about the women and their husband’s t-shirt, but this had more experiments done on it. The second article is a scientific article about human pheromone and the impact it has on sexual attraction and social behaviors in general. This article also seems to support that we do have pheromones that can subconsciously impact us. I found these article really interesting. When are attracted to someone, their pheromone is almost unnoticeable, yet the experiments in the articles seem to suggest smell has a larger impact on our decisions than we thought. Scent does have a large influence on us though. The scents that you can smell consciously can actually bring out memories faster than most other senses. I guess the subconscious scents can have an effect too.

http://www.smithsonianmag.com/science-nature/the-truth-about-pheromones-100363955/?no-ist

http://www.sciencedirect.com/science/article/pii/S0301211504004749

Cardiovascular disease (CVD) is one of the leading causes of death not just in American society but globally. Millions of people die every year from various forms of heart disease, two of the more common ones being hypertension and atherosclerosis. Because it is such a major health problem in modern society, much research has been and is being done to find ways to help treat the symptoms and causes of the disease, to help find ways to prevent people from developing heart disease, and to understand the genetic and epigenetic causes behind the disease. However, what Dan Yang and Zhihua Liu discuss in their paper is the necessity of looking at CVD in an evolutionary context if we are to be able to more comprehensively understand CVD and how to treat it the most effectively.

One of the biggest factors that contributes to CVD in humans that Yang and Liu point out is that we are currently experiencing an evolutionary mismatch with our environment. That is, our diet and lifestyle in modern society is very different from what it was as recently as 10,000 years ago. We now eat more food (much of which is modified from its natural state), have a much more sedentary lifestyle, are under more/different types of social and psychological pressures, and engage in many more harmful activities (smoking, alcohol consumption, etc.). All of these are risk factors for CVD, and most are the result of our society evolving faster than natural selection can act. As a result, our genetic makeup is not suited to deal with many of these aspects of modern society, which leaves us susceptible to CVD.

Yang and Liu then discuss what this perspective means for the future of researching CVD. A lot of research is focused on the genetic (and epigenetic) causes of CVD, and manipulating genetic and epigenetic factors can have a lot of downstream effects that might not be anticipated. Therefore they urge researchers to keep in mind the evolutionary context and purpose of the genes that are being manipulated, because otherwise genetic manipulation can end in disaster.

I found this article very interesting, because CVD is of personal interest but also because it is a very complicated form of disease. We can and should do a lot of investigating into the mechanics of CVD, but if we don’t understand why it occurs (which means understanding the evolutionary context of the disease and the history and purpose of the genes that are involved in it) then we can’t treat and prevent it in the most effective manner – the obvious goal of researchers and physicians. Their optimism about evolutionary medicine becoming a mainstream science was encouraging, and hopefully we will see more of this type of research in the coming years.

A team at the University of Copenhagen were able to track down a genetic mutation that took place 6 to 10,000 years ago in the OCA2 gene that was able to create a “switch” which turned off the ability to produce brown eyes, by limiting the action of the gene to produce melanin in the iris, and dilute brown eyes to blue. Further, there is limited genetic and phenotypic variation in the eyes of blue – eyed people. For example, variation in melanin causes the differences in brown and green eye color, but blue-eyed individuals exhibit very little variation in the amount of melanin in their eyes, and also have inherited the same mutation at the exact same locus on their DNA, lending to the theory that all blue-eyed individuals have a common ancestor and the mutation is found to be passed maternally. Mitochondrial DNA was examined from diverse countries such as Jordan, Denmark, and Turkey (1).

However, the question most people, at least when it comes to our class, have is what does this mean in the context of evolution and natural selection? The answer: depends on who you ask. Some articles (1) claim that the mutation of brown eyes is neither a positive or negative mutation. Just as other mutations (hair color, baldness, etc.) do not increase or decrease a human’s chance of survival; hence nature has attempted to merely switch up the genome in this cocktail theory. It is interesting from a student perspective, to remind ourselves that sometimes nature does not necessarily directly work in favor of increased fitness.

On the other hand, others assert (2) that the mutation arose through the mechanism of sex selection, which we in our previous class understood as “ornamental demonstration” where in an area of increased competition for reproduction, males and females will choose their mates due to one peculiarity or phenotypic variance (such as with seen in the demonstration of male peacocks) in an effort to diversify genes and subsequently increase fitness.

Though, I agree much additional research is needed regarding the mechanism and the common – ancestor theory itself, it is an interesting topic, and increased studies across multiple population – types may be helpful.

This paper highlights how human movement greatly affects the transmission of vector-borne diseases; specifically dengue.  This paper also notes that the behavior of vectors also plays an important role in disease transmission.  Vector behavior can range from activity (nocturnal) to the biting patterns of the vector. The fact that vectors may be attracted to certain hosts over others also must be taken into account. I think the strength of this paper is the model used to support the data. The model is termed ‘the activity space model’. Spatial arrangement can be broad (international) and local. This model focuses on the few places that individuals spend most of their time (local). The big idea is to use human habitual behaviors to track the places they spend the most time. These individual movements are broken down into spatial and temporal scales. From this model authors concluded that movements with greater spatial arrangements usually involve more time, but not always. The most important thing that the model shows is which movements actually are important when looking at rates of transmission versus those that do not really contribute to transmission. I did find all the different equations a little confusing.  Overall, the data from this paper can help better disease prevention programs.

Although obesity is an unfavorable trait, there is evidence that in the past storing fat was quite beneficial. The body was apt to store fat to prepare for long periods of famine in our ancient history. This thrifty gene hypothesis was originally proposed by James Neel. Obesity leads to many health complications, one of the most common being Diabetes.

There are a high percentage of Native American populations that have Type 2 Diabetes. Unnatural Causes: Bad Sugar, a documentary,  delves into the many ways that other factors have contributed to the genetic predisposition of Diabetes in the Pima Indian population of Arizona. Many of these factors happen to be political/economic issues. For instances, the Coolage dam diverted water from the Gila River (major water source in the Pima community) away from the reservation.  The Pima Indians were left with little water resources for their crops and for survival, making them one of the poorest populations in America at the time. This severely affected the Pima economically and culturally. They had to learn to survive without water and adequate food.  Many of the Pima died from starvation during this time of famine. Within 30 years of building the dam there were more than 500 cases of diabetes among the Pima Indians. This supports the thrifty genotype hypothesis. Their bodies were used to not receiving adequate nutrition so the body evolved to hold onto more fat than usual for survival. After a while the government provided food subsidies, but they were not healthy options. The Pima community did not have markets where fresh produce was abundant so they had to rely on processed food that had low nutritional value, provided by the American governemtn. This resulted in even higher rates of diabetes in the population today.

I think that the story of the Pima community in Arizona is a good example of our class discussion on how the human genome evolves simultaneously with our environment and culture.  There is evidence that many minority groups, such as African Americans, that have experienced extreme hard ship in history have high rates of diabetes as well.