Fareeha Khan

Seminar C 2

LLOG 6: Our Flesh and Blood

Synopsis

Coevolution and the arms race

Coevolution describes such instances in which the predator and the prey seem favored by natural selection. In such situations, both adapt increasingly helpful features that help both of them survive despite each other’s roles to out live the other.  This could be compared to an arms race because both ideas have the same level of panicky struggles to beat the opposing force and both ideas result in obtaining a multitude of means to fight back. An example of this is of the Thamnophis sirtalis snake that has been able to continue adapting a resistance to eating the toxic newt that have become increasingly toxic in correlation with the snakes’ evolution of defiance.

Evolution of skin color

Skin color is a very evident differentiating factor found in humans. Darker skin colors are found in the more tropic areas while lighter ones reside in colder temperatures. Even a non-native skin color will adapt to survive in a certain area, for example this can be as simple as a tan over the summer. This is the basis for the hypothesis made that skin color depends on the physical environment the human lives in. Skin color actually is determined by the amount of melanin in the skin, which acts as a natural sunscreen. It can regulate the amount of UV radiation that goes through the skin. Another factor that determines skin color is diseases. Certain infectious diseases found in the tropics cannot affect dark skinned natives that are immune to such diseases. In colder areas no such diseases exist so the need for skin to resist that is unnecessary. Thus skin color seems to be a legitimate example of a variation of natural selection.

Sickle Cell Anemia Mutation

The sickle cell blood mutation was first discovered in 1910. It has been prevelant in many tribes across Kenya. It turns a normal blood cell into a sickle shape caused by abnormal hemoglobin. In a 1949 study done by Anthony Allison, it was found that the sickle cell trait varied depending on what region the Kenyan tribe lived in. Those close to the coast or Lake Victoria had a high rate of the mutation while those who lived in highlands had a much lower rate. Allison found that the frequency of sickle cells depends on the resistance to malaria. Those nearer water are more likely to get bitten by mosquitoes carrying malaria and thus are more likely to have sickle cells, which protected them by making them resistant to malaria. The reason why bad mutations can survive despite ill effects is because of the survival advantages it can offer when just one copy of the mutation is present in a body instead of two.

Coevolution and Malaria

Coevolution can be seen in the example of humans and malaria. While malaria continues to persist and attempts to thrive in human bodies, humans have formed adaptations to resist the disease with sickle blood cells. Malaria fights back by increasing populations of mosquitoes that carry the disease while humans continue to make adaptations and medicines to resist it. Another example of humans and a pathogen coevolving can be found in cancer. Cancer can be formed by a variety of reasons now and seems to almost prevail over human resistance however humans have stayed strong in studying the disease and finding cures to prevent it. As we continue to study and practice medicine we are coming closer to finding the cure.

Combination Treatments

Combinations of drugs may be the new, most effective solution to fight pathogens. This is a very logical solution when looked at carefully. 1 in 100 million parasites are resistant to drug A but 1 in 10,000 trillion parasites are resistant to drug A and B together. The chances are significantly less than the combination will be defeated by the parasites.

Cancer

Cancer has recently been one of the most deadly diseases known to man. Several million are lost each year to the disease. Treatments most commonly consist of toxic drugs and radiation. Some forms of leukemia cells have formed a resistance to the type of toxin that has been developed to get rid of the cancerous cells because of other mutations that have formed in the cells. However, not all hope is lost. New methods are being developed to circumvent these resistant cells. Scientists have discovered that combination therapy can beat the Gleevec-resistant cells that form cancer. Gleevec is a type of toxin that has been attempted to get rid of leukemia. This is a breakthrough achievement. With further studies of evolution and possible human adaptations we can prevail in this arms race.

Take Away Idea

The idea that I think is most essential form this chapter is that of Coevolution being related to an arms race. It is a scary concept but is necessary to understand. If we understand that even though the opposing side, for example the parasites, may form a mutation to make humans sick despite our adaptations we can also fight back and can find natural selection to be on our side. This idea reminds people not to give up hope.

Most Challenging Concept

For me the most difficult concept to understand has been that of how natural selection can both favor a species but also favor the enemy. It was hard for me to understand why the mosquitoes became more and more abundant, almost defeating the humans’ form of protection from malaria. After rereading the section I came to realize that a certain mutation can be effective when presented in only one form and can be considered dangerous when found in more forms. Natural selection works in mysterious ways.

A Seminar Question

Do you think humans can prevail in finding a cure for cancer or do you think cancer will continue to form adaptations to defeat humans?

Competency

Communication is a very important factor in Coevolution.  For example, it is necessary for scientists around the world to update each other on new developments on the studies of certain diseases. With the various tools available at different spectrums of the world, this will aid humans in finding a cure for a certain disease as soon as possible. For example, scientists studying sickle blood cells in Kenya could report this information to scientists in America who could study this new found content in highly technological labs.

Aesthetic Awareness is also a key component in Coevolution. Being able to look at fine details very carefully is what has led us forward to the point at which we are at now with regards to information we have collected on Coevolution. For example, being able to understand that a mutation that seems harmful in one copy can actually be helpful while in two copies it can be dangerous. Knowing this can help us in developing cures for a variety of diseases.

Connection

The Coevolution of parasites and humans that I’ve read about in this chapter reminds me of the Coevolution of different regions of humans that fight wars against each other. As one region, say the western part of the world, gains power and highly sophisticated technology another part of the region, say the eastern part, will also attempt to gain some sort of power and technology as the two differing regions continue to threaten each other. This is the real life, tangible and incredibly scary arms race that we have seen develop in the past decades. As one country gains access to some sort of deadly form of fighting then another country will develop an even deadlier form. This race seems to see no end and continues to be an ever-growing fear that the world looks at with huge deer in headlight eyes.

Vocabulary

1. chronic myelogenous leukemia- also known as CML, a type of cancer that is resistant to Gleevec
2. Gleevec- also known as Imatinib, a type of drug that latches itself onto a specific part of the a protein that promotes cancer and inhibits its activity.
3. Impediment- something that hinders a process

Key Concepts

1. The arms race of Coevolution shows that natural selection can help two different species for different reasons even if these two species have a predator-prey relationship.
2. A mutation that seems harmful may actually be helpful when only a certain number of copies exist which is why the seemingly devastating mutation is flourishing.
3. Skin color of humans is a visible example of natural selection working in different ways with the same species.