All posts by klipner

Final Paper

For my last blog post, I think it’s appropriate to post my idea for my final paper. My paper aims to answer the question, why do humans use contraception if according to strictly evolutionary terms, each individual’s ultimate goal should be to reproduce infinitely? I decided to approach answering the question by first finding examples of natural checks on offspring numbers in other species (which is comparable to our means of artificial control over offspring numbers). Most of the data I encountered was found in birds. One of the most extreme examples off offspring number control was in the Altricial bird. When food is scarce at the time of recently hatched offspring, the siblings compete to get the most food. In this way, a sort of size hierarchy is created as the largest birds are able to outcompete their nest mates. Often, the smallest of the offspring starves to death: a natural check on number of offspring (Godfray et. al.).

A similar check can be found in humans but it is expressed in writing quite differently. It makes sense to say that humans can only have as many children as they can support financially. This is just like how if there are too many offspring in a laying, one of the offspring will most likely starve due to lack of food resources. So, when someone says they use contraceptives to avoid a pregnancy due to financial reasons, although it sounds very different, the comparison to the altricial bird is actually quite similar-it has to do with available resources.

My paper expands upon these ideas, has more examples, more in depth explanation of reasoning to avoid pregnancy in humans, and also the greater evolutionary concept at work. The paper that mentions the Altricial bird is linked below.

Summary of Reading for 4/17/14



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.

Down with the Human Race

In class we have discussed that it is imperative to our understanding of evolution and natural selection that no one species is more advanced than another. It is a fundamental principle that also leads to the understanding that as species evolve, it is not with the goal in mind of being a “perfect” or the best species on the planet. Instead, a species evolves to be as well adapted to its current environment as possible (and of course it is not doing that by conscious choice but by natural selection).

We all have a grasp on these concepts. What I did not know was that some have inflated these ideas to an extreme. According to this video (see link below) there is a growing population of people who believe that because humans are technically no “better” than any other species that we should depopulate for the sake of the life of all other species. These extremists argue that humans are a plague upon the Earth that are destroying the planet for all other organisms. They say this simply because of the fact that humans are no more advanced or superior than any other species.

The video goes on to articulate implications of this ideology. The one that stood out to me was the fact that if we legally equivocate animals to humans, then all of us would have to become vegetarians. Secondly, animals would be able to bring up lawsuits against humans for issues such as maltreatment (the animal of course would be unable to do this but one of these extremists would do so for them). The most extreme of the extremists would even argue that plants have rights, so we would have to stop consuming plants as well.

In my opinion, these extremist ideas are nothing short of insane. But I cannot deny that the concept these ideas are based on is actually 100% correct and is fundamental to understanding evolutionary medicine.



This article in the New York Times talks about how dust mites are proof that evolution does not always move forward but can actually regress. A study in the University of Michigan found that  the phylogenetic tree of dust mites shows that dust mites themselves are free-living organisms, and they evolved from parasites, and parasites evolved from free-living organisms. This article stood out to me because it reminded me of our discussion in class that covered how no one organism is the “most advanced,” but rather all organisms have evolved to be best fit to their particular environments. Understanding that concept,  I would suppose that a long time ago free living organisms were no longer a good fit for a certain environment and so after a long period, parasitic organisms evolved by natural selection. Then, in another environment, being a parasitic organism was no longer favorable and being free-living was a better fit, and so natural selection created the free-living dust mite.  Natural selection selects for organisms to fit their environments, there is no goal of creating the ultimate, perfect organism. If becoming a better fit for the environment means the return of a trait of an ancestral organism, the fact that the trait was previously discarded is irrelevant; that trait is now a good fit again.

To tie this in with medicine, the article concludes by saying that discovering the free-living nature of dust mites gives a new genetic insight into these organisms that will help scientists to understand how people with dust allergies react to dust mites, possibly leading to the production of a better allergy medication. If only there could also be some medical advancement in spring allergies too; it’s almost that time of year. Makes you wonder why evolution has not eliminated allergies in general: dust or pollen based.

The article’s link is below:

Why we have Four Limbs

This article contains a possible, evolutionary answer as to why all animals with a backbone and jaw develop with four limbs (based on the scholarly publication published by Laura Nuno de la Rosa). The hypothesis is that limbs develop in areas where the layers of tissue (during early development) are separated enough for an appendage to form-it just so happens that the location of the separations and their favorable interactions with other tissues allow those limbs to form. What struck me the most about the article was not its content but instead a line that reads,  “As with any long-standing question in evolutionary biology, numerous ideas have been proposed to explain different aspects of the origin of paired appendages in vertebrates” (Science Daily). This reminded me of our discussion in class about the importance of thinking through all possible hypotheses to these evolutionary or distal questions. Also noteworthy is a line in the article that reads, “…the focus of the hypothesis on global embryonic patterning and tissue interactions emphasizes the importance of accounting for factors other than genes (epigenetics) to understand development and evolution” (Science Daily). With that, the author emphasizes the importance of viewing evolutionary issues at a macroscopic level instead of only focusing on the microscopic, DNA level. That is certainly another interesting idea to keep in mind when considering our upcoming assignment…Here’s the link to the article. At the end of the text, there is a citation of the the scholarly publication the article is based on as well.