quick chap 6 recap!

Natural selection picks the mutated organisms that are best adapted for survival. But the mutations are not the result of purely random mistakes during gene replication. Darwin postulated that mutations are the result of cell reproduction errors, but an alternate theory, set forth in recent times by Barbara McClintock, that holds more water is that we have perhaps evolved to actively mutate our genes when the environment changes, so as to give our offspring a better chance for survival.

Viruses exhibit this behavior, when antigenic drift causes original mutations in a disease. After a solar flare-up in 1917, two deadly smallpox outbreaks killed millions of people. It is possible that the virus strains mutated when they were irradiated. Antigenic shift, when a virus gets new genes from a similar strain of virus, is also a form of survival enhancing mutation. Viruses also have genes that jump around and either copy and paste or cut and paste new sequences around. Scientists are really interested in these jumping genes, and have taken to giving them punny names like Jordan and Evelknievel. We also have “jumping genes.” Scientists think these are former viruses that we have swallowed into our DNA. 97% of our DNA is used for mutational purposes.We are programmed to mutate if we need to. Our DNA is like a smart computer program that seeks input, not just a simple string of commands that occasionally fail at replication.