Wednesday, December 19, 2012

Stress ---> The Dutch Hunger Winter




The Dutch Hunger Winter was one of the saddest human tragedies that happened in 20th century. It was a famine that took place in Netherlands which was at that time occupied by Germans. In winter of 1944-1945 in order to punish the Dutch who didn't want to support and help Germans in Nazi war, Germans made a blockade that cut off food and fuel shipments. Food supplies became increasingly scarce which caused famine to start spreading throughout the country. People ate grass and were trying to survive only on 30 percent of the normal daily calorie intake. More that 4.5 million of people were affected by this famine and they survived only because of soup kitchens.Unfortunately, around 22,000 people died from starving.
Epi­demiologists  decided to study an effect of famine on the birth weights of babies who had been inside of their mothers' wombs during the Dutch Hunger Winter. What they found out was that if a mother was well fed during the pregnancy and was starving and malnourished only for the last three months of the pregnancy, her baby would be very small. On the other hand, if a mother was malnourished and starving only for the first 3 months of the pregnancy and then she was started being fed, her baby would have a normal weight. However, this wasn't the end of their study. Epidemiologists studied these babies and their weights for decades. They noticed that people who were born very small  stayed smaller for the rest of their lives with lower obesity rates than the population. It is really interesting because these people had already an access to food. They could have eaten as much as they wanted, but their bodies never got over malnutrition that happened during their early life. On the other hand, people whose mothers were starving only for the first three months of their pregnancy had higher obesity rates than normal people. These people had also some health and mental problems during their life. What was even more surprising was that even children of these people and next generations had some effects presented from their grand mothers or great grand mothers who were starving and malnour­ished during the first three months of their pregnancy. Epidemiologists concluded that events that take place during the first three months of pregnancy, when the fetus is small and grows rapidly, can have a big impact on the rest of a person's life. This study is an example of how epigenetics works. Epigenetics (above genetics) is the study of heritable changes that occur in gene expression or in cellular phenotype and are caused by mechanism other than changes in the DNA sequence.  It is a mechanism in which cells with the same genetic code express different parts of it. It's important to realize that epigenetics has an enormous impact on human health. Epigenetics helps us to realize that there's a ling  between nature and nurture: "how our environment talks to us and alters us, sometimes forever." The conclusion of The Dutch Hunger Winter study is that environment does affect us and our lives.

Sunday, December 9, 2012

The Theory of Evolution & Psychology

1. Theory of Evolution that was first formulated by Charles Darwin says: a) more offspring are produced that can possibly mate and survive, b) individuals have different traits which leads to differential rates of survival and reproduction, c) these trait differences are heritable. In this theory Charles Darwin focuses on natural selection.

2. and 3. It's important to say that both nature and nurture influence organism's trait. Nature stands for a biological influence while nurture stands for an environmental influence. It has been a controversial topic because some traits have been defined by a behavior rather than by physical characteristics. However, all traits are determined by genes working through environment.

4. Social Darwinism talks about the survival of the fittest. It says that people on the top are people who are best suited to existing living conditions.

5. Eugenics: In order to improve human heredity there should be a higher rate of reproduction of desired people and a lower rate of reproduction of less desired people. It basically means the production of superior humans by selective breeding.

6. The problem of eugenics is that it is very unethical and you can't really control the reproduction of all people on the world.

7. Fitness can be described as the ability to reproduce and survive.

8. Genetic Determination means that if something is genetic then it cannot be changed, therefore it's better to not investigate it.

9. A gene that is very common can become a design feature of a human being, which means that this trait is "fixated" and the only way to change it it's through mutation.

10. Canalization happens when a trait is controlled by one of a family of genes that all produce the same result.

11. Punctuated Equilibrium talks about few mutations of genes that can cause a large change in evolution.

12. Evolution created Evolutionary Psychology that provides framework for thinking about human behavior and how it evolves over the time. If observes differences to the way we think about ourselves.



13. Evolutionary Explanation of Behavior: Leopards

All of the leopards have slightly different genes which means that each of them has different lung capacity, muscle mass, volume and connectivity of nervous system fibers. Because of these small differences some leopards are better at hunting, feeding, or running than the others. Leopards that are better at hunting or feeding will usually live longer and reproduce more often than the others. This means that their will make more copies of their genes and then they will pass them on. This eventually will lead to a production of a new population of leopards that will be, on average, faster, or will have better sight than the previous generation.