The article on Evolution and Origins of disease by Nesse and Williams explains the concepts of evolutionary biology very well. Evolutionary biology is supposed to be the foundation for all other biological fields. According to Darwinian medicine, our body is made a certain way making us susceptible to cancer, choking, depression, etc. They are not due to diseases or design of the body.There is a need to further investigate because they can help us understand the anatomy and physiology of the body and how it relates to evolution. There are certain explanations for conditions in evolutionary biology. For instance, the conditions like pain, cough, vomiting, anxiety, etc are considered evolved defenses. One great example is fever. When we experience fever, our body temperature rises. This is because our body is killing pathogens. So, fever can be regarded as an evolved defense. Another example is that of iron. Iron is an important element of the body. It is believed that the low iron in the body is caused by illness. However, in the words of evolutionary biology, it is a defense mechanism. Low iron prevents the pathogens from using the important element for themselves. One interesting explanation is that our body can sometimes struggle when it comes to a specific’s trait’s benefits and costs. For example, people with sickle cell gene are protected against malaria. Having a sickle cell gene is harmful and makes up the cost part and protection against malaria makes up the benefit part. According to evolutionary biology, the body has become victim to the cost and benefit components of sickle cell gene. It is also believed that we are not protected from the pathogens because natural selection causes some other organisms to evolve at a faster rate than us. Pathogens also tend to develop a counter-defense for our defenses. For example, the antibiotic resistance has been increasing rapidly and is considered an evolutionary adaptation. Therefore, we catch infections. However, this does not mean that humans are not evolving. We have been evolving just not at the same rate as other microorganisms. The proof of this is the availability of gene data. It has helped us study evolutionary mechanisms that have occured. For example, we studied traits that have been highly selected and has spread fast like the hair color. The genomic system has also helped us understand the vitamin D deficiency in different groups. People who have lighter skin tone are able to absorb more vitamin D than people with darker skin tone. It has to do with melanin in the body. This again, can be studied with genes. Like people with blonde hair, tend to have lighter skin tone. We would see less cases of vitamin D deficiency in these people. While in people who have a lot of melanin in the body, we will see many cases of vitamin D deficiency. Genomic system and advanced sequencing can also help us track the sexual selection that has occured in the past and is currently happening.