Darwin’s Surprise

Darwin is known for proposing a mechanism of evolution and for his idea of descent with modification. He proposed that all living organisms descended from the universal common ancestor and environmental pressures resulted in the rise of new species. When explaining the concept of evolution, Darwin only took environmental factors into consideration but he would be surprised to find out that the interaction of all living organisms with viruses, which are non living particles, also influenced their acquisition of certain traits.

What I found the most interesting about the article was how chimpanzees are more easily infected by the AIDS virus than humans but they do not get sick from it. We are very closely related to chimpanzees and have nearly identical genomes, including our endogenous viral fragments. The major difference is the presence of the Pan troglodytes endogenous retrovirus (ptERV). The chimp genome contains about 130 copies of PtERV while the human genome contains none. Evolutionary biologists have been able to discover the lack of PtERV in our genome is due to TRIM5a, a gene that codes for protein that destroys PtERV. Due to this gene, we didn’t get infected by PtERV but it has also made us especially vulnerable to AIDS. In biology, the idea that every advantage is accompanied by a cost is prevalent and this case is no different.

The important role that viruses have played in evolution of many species is highlighted in this article. Without them, we would not have acquired the traits that define our species. For example, without retroviruses, mammals would have never developed the placenta. This would have prevented the evolution of many species, including humans.

This article has made me see viruses in a more positive light. When one hears the word “virus”, negative connotations immediately come up to mind: infections, cancer, unstoppable, etc. but this article forced me to view viruses in from a different perspective. It has made me realize that we would not have evolved into the species we are today without them.

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