Journey of Man Day

Today, we reviewed our test and what we learned from the homework assignment the night before, then we watched a video regarding the "Journey of Man," and how we got to where we are today.

Response to Article 1, "Does Race Exist?"

Nowadays, it is often preached that race should be ignored because we are all humans at heart, that just because our skin color is different doesn't mean we don't function the same way. Recent findings have supported this theory and have given it meaning in the biological world. 

Upon reading "Does Race Exist," I have learned that the concept of race is invalid in comparing humans and our ancestors. When we think of race, we think of physical appearance such as dark skin, or light skin, curly hair, or straight hair, brown eyes, or blue eyes. Although race does sometimes account for different resistants to disease, these physical differences are essentially meaningless in providing evidence for where we came from. People are affected by numerous variations and mutations and although two people may have similar appearances, they could come from completely different environments and have completely different ancestors. Because people look similar does not mean that they are genetically similar. Also, in contrast, people may seem genetically dissimilar because natural selection has exaggerated the differences in appearance, making them more similar underneath than on the surface. Thus, scientists must look at genetic makeup to determine where we came from.

As explained in "Journey of Man," evolution is created through variations of genes that  are then passed down from generation to generation and then those genes are then variated some more down the line. Some variations do not occur within genes, and do not directly affect a particular trait. These variations, known as polymorphisms, are variations in the building blocks of DNA, which scientists study to show individual variations in traits and genetic diseases. Upon studying polymorphisms, scientists are able to see the these variations come from natural selection. As variations that allow species to survive and reproduce better are passed on, the DNA strands of the next generations differ from their ancestors and thus make the search for our ancestors more difficult.

Another tool of polymorphisms that scientists use are Alus, or similar pieces of DNA. Once an Alu is placed, it remains there for eons and is passed onto the following generations, giving scientists another tool to track down our ancestors. For example, if two people have the same Alu then they are descendants of a common ancestor. Scientists have been able to break the myth of race using Alus. By comparing Alus from different populations and sorting people off of their Alu similarity, there was little parallel between Alu similarity and race. When scientists studied different populations based on their Alu differences, they were able to draw connections from all the populations to two places, thus proving that genetic differences can be studied to discover geographical origin, or at least obtain a small sense of it.

Genetic variations account for different defenses against diseases. For example, people that lack the CCR5 polymorphism are less susceptible to HIV-1 because it hooks onto the CCR5 in order to enter our system. We have been able to see that polymorphisms affect different populations differently. For example, a common polymorphism found in Europeans delays a certain type of disease while the same polymorphism accelerates the disease in Africans. Therefore, but studying different details of genetic differences, scientists have been able to separate different populations into different classifications and are that much closer to discovering our human origin.