Hey Darwin… Surprise surprise!

Darwin discovered evolution without knowledge of genetics or DNA.  All of his ideas and research was based on phenotypic expression in the finches that he studied.  Even though he didn’t know about genetics, he knew that organisms were evolving.   By observing phenotypic changes in his finches, he realized that the traits that were perpetuated in a population were the ones that were advantageous.  Darwin proposed that nature was selecting for these most adaptable and fit individuals by granting them greater reproductive success.  This way, the traits that helped an organism survive were conserved in a population.  But hey Darwin, would you consider a virus advantageous for an individual? Of course not! A virus is our number one enemy.  It’s a parasite that infects our cells and utilizes them to produce more viruses.  The fact that viruses have been in our genomes for so long and that they actually might be beneficial to us would have been surprising to Darwin.  Multiple studies have been conducted that connect the evolution of a placenta in mammals to viruses.  It would have surprised Darwin to know that a placenta, something so revolutionary in evolution that made live births possible, originated from a retrovirus embedded in our DNA.

What I found most surprising was that even though chimps and humans are very closely related, we have developed different immunities to different viruses.  Chimps are immune to HIV, a disease that has devastated the human population.  On the other hand, we are immune to PtERV, a disease that chimps have no immunity to.  How is it that there is no trace of humans being infected by PtERV?  And how is it that chimps can be infected by AIDS yet not get sick?  I would assume that because our genomes are so similar, we would have immunities to the same viruses, but I guess not.  Something else that was surprising to me was that when scientists tried to assemble a protein to fight off both HIV and PtERV, they realized that it would only fight off one or the other.  Why is that?  Is this the reason that humans and chimps are immune to different viruses?

This article suggests that viruses may have been essential to our development and the development of other species.  Advantageous traits, such as a placenta, may have originated from viruses.  Without this trait, we would still be laying eggs.  The insertion of virus genetic sequences into our genome caused phenotypic changes in us that ended up increasing our fitness.  Not only are viruses crucial in the process of evolution, but they are also helpful in uncovering the process of evolution.  Through the study of viruses, we can go back in time millions of years and possibly find cures for viruses like HIV that pose a great threat to us.  This has changed my understanding of viruses because now I know that they aren’t just harmful parasites that destroy our cells.  If mutated or reassembled, they can actually help us.

I think that “reviving” dead viruses can be very beneficial for us.  If we figure out how these viruses work and function, we can eventually develop cures.  This will change the world, as illnesses such as AIDS could possibly be eliminated forever and become “extinct.”  I still think that it is risky reviving these dead viruses, because if anything were to happen where this virus would be reintroduced to our population, the results could be devastating.  Overall, if we are careful and smart about which viruses we reassemble and study, we’ll end up benefiting.

This entry was posted in AP Biology, Evolution, Viruses. Bookmark the permalink.

One Response to Hey Darwin… Surprise surprise!

  1. MaryH says:

    I think the point you made about viruses being not only critical to the process of evolution, but critical towards uncovering that process was very apt. I had a similar revelation and response towards this article. How is it that something with the potential to eradicate our species may be beneficial? For Darwin, with no knowledge of genes, this probably would be very surprising. After all, sickness does not generally lead to higher rates of survival or reproduction. But the idea that endogenous retroviruses have been incorporated into organism’s genomes and passed down in ways that have led to the expression of beneficial traits like syncitin protein production in the placenta? Now that’s definitely an area of interest. The point you brought up about HIV’s presence in humans and PtERV in apes was a good one. For two species so closely evolutionarily related, there must be a reason for discrepancy. The TRIM5alpha gene, which protects humans from PtERV but not HIV, and apes from HIV but not PtERV. This gene in itself is an evolutionary connection, with the change in protection derived around 5 million years ago when humans split from chimps. Obviously, resistance to both HIV and PtERV would be ideal, but this would require more research and a greater understanding of the TRIM5alpha gene. More research could be incredibly helpful in disease treatment and prevention. Viruses really can change the world, and the reality is that they already have.

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