In chapter 6 of Survival of the Sickest, it talks about how scientists have realized that DNA can be modified by other factors, and not just random mutations. Lamarckism or, the inheritance of acquired traits, seems to be superseding the original theory of Darwin that is mentioned in his book Origin of the Species. Barbara McClintock provided evidence in the 1950's for traits caused by jumping genes. Jumping genes are whole sequences of DNA that has been prompted to move from one place to another, by stress in the environment. Occasionally, jumping genes, or transposons, preform a "cut and paste" process, or a "copy and paste" process. Cut and paste is when whole sequences are removed and relocated, and copy and paste is when sequences are duplicated first, and then relocated. Jumping genes are what make up large portions of our junk DNA, or DNA that does not code for proteins.
This chapter also talked about the relationship of viruses, DNA, and RNA. Retroviruses are made up of RNA and can be inserted into, or written into, DNA. HIV is an example of a retrovirus, and is combated by the drug "cocktail" therapy. Cocktail therapy targets the enzyme that helps RNA become apart of DNA, in the hopes of slowing the process. Retroviruses that are already a part of DNA are called HERV's, also known as Human Endogenous Retroviruses. Some HERV's have a positive effect on DNA and are known for playing a number of roles such as producing a healthy placenta.
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