Please complete both parts of this assignment in the same document. The title of your document should include your name, like so: "your name_module2_assignment". Upload your work to me by clicking on the "Submit Assignment" link on the right. 1. Pick a behavior that is considered pathological in our society and that you have a strong suspicion has genetic roots. Using evolutionary theory, describe the evolutionary basis of that behavior, speculating why it might appear despite the disadvantages of being pathological. Your answer should require no more than 1-2 single-spaced pages. According to evolutionary theory, traits that are advantageous in some way are more likely to be passed on to offspring and remain in our species. Bipolar disorder is considered pathological but I believe has a genetic component. Perhaps the gene bipolar disorder is carried on is also associated with protection against another disease, like sickle cell anemia protects against malaria. Therefore, people with bipolar disorder would’ve been more likely to survive historically than people without bipolar disorder, and the disorder would that way remain in the human species’ genetic makeup. Like with Schizophrenia, the manic phases could be associated with greater creativity. In ancient times, greater creativity could’ve been associated with finding innovative ways to kill animals to eat or new ways to create solid shelter. Either of these strategies could’ve led to a greater chance of survival, and thus the gene would’ve been carried on in our species. One symptom of mania can be increased sexual desire, which could potentially lead to a greater number of offspring in people with bipolar disorder, since people with increased sexual desire would be more likely to have sex and have children. This would mean any gene connected with it would be more likely to be propagated in the human species. Another symptom of mania can be increased energy, which in ancient times could be extremely beneficial; those with more energy might spend more time hunting or foraging, and thus would have more food available for themselves and their offspring. Another symptom of mania can be taking risks. Taking risks could’ve also allowed people to be more likely to survive and reproduce. Maybe they were more willing to go after larger more dangerous prey, which potentially would give them more food. Or maybe they were more willing to leave a region with scarce resources and move to a new area in the world that might have more resources. A symptom of depression is fatigue and sleeping a lot and loss of appetite. Perhaps long ago during times of famine, depression helped people conserve energy and not require as much food which would’ve helped them survive. Another symptom of depression is decreased sexual desire; perhaps this would’ve also been beneficial in times of famine, when offspring would’ve been unlikely to survive and also take away calories from other members of the tribe. I read somewhere once that woman with bipolar were more likely to marry up in the social hierarchy, which could lead to more offspring and the gene being propagated; females that attracted males higher up in the social hierarchy long ago, would’ve been more likely to get better/more food and thus more likely to propagate. Perhaps there is something appealing to males in woman who are manic that attracts them (maybe their increased sexual desire!) or also the creativity that could be associated with bipolar disorder could help woman find unique ways to attract and keep a quality mate. 2. For years we were taught Mendel's view that, barring mutation, genes were passed, unchanged, from one generation to the next. Explain how epigenesis makes the situation more complicated than that, and how an environmental influence on one of the parents could be passed onto the child genetically. Your answer should require no more than 1-2 single-spaced pages. It used to be thought that genes were passed unchanged from one generation to the next. However, although genes themselves are passed on from one generation to the next, parental experience can affect whether genes are switched on, which influences the expression of the genes. This is called epigenetic inheritance. DNA is wrapped up in proteins called histones and then further bundled up into chromosomes. By being tightly packed like this, the genes are in an inactive state that prevents them from being turned on. When an action is needed acetyl groups unfurl DNA and allow access (they are called writers) and methyl groups do the oppose, and prevent DNA access (they are called erasers). These tags allow organisms to respond to changes in the environment. In rats, mothers that were more nurturing resulted in less stressed offspring. These offspring were more likely to be more nurturing themselves when they grew up. It was shown that they differed epigenetically. Pups raised by these more nurturing mothers had less DNA methylation than pups with more passive mothers. There are many other studies that have shown examples of epigenetics such as the diet of a female mouse before conception can influence her offspring’s hair color and even their offspring’s hair color as well. Also take the example of children of Holocaust survivors. They are more likely to have psychosomatic issues than average. It used to be thought that this was due to how they were being raised; perhaps due to the parents’ extreme stress they were overly cautious with their children. But now it is known that this is not the reason. In the case the extreme stressful situation of the holocaust caused some genes to be bound by methyl groups which makes them inaccessible. Specifically, genes that reduce cortisol which therefore reduces the stress response to a situation might be bound by methyl groups in the parent’s cells, which get passed onto the children as such. The children inherit the genes that would allow them to calm down in response to a stressful situation, but those genes are closed off, and therefore the children’s stress level remains high in certain situations leading to more physical complaints that are psychological in nature. All of these examples indicate that behavior and environment of parents can influence characteristics in later generations. This is extremely interesting because it makes the nature versus nurture question ever more complicated since the environment and genetics are more interrelated than previously thought. The fact that environment (nurture) can affect genes (nature) makes in more difficult to separate the two. It reminds me of the Droste effect of a picture within a picture infinitively. Environment affects genetics which affects environment, etcetera. As a side note, I am particularly now interested in epigenetics for a personal reason; I have two adopted children from foster care who experienced severe trauma and deprivation in their early years, and epigenetics could help explain why some of their behaviors exist and are difficult to change, such as mood dysregulation.
