“Darwin’s Surprise” was full of surprises

It took me a while to process what I read in Darwin’s Surprise, mainly because I was in awe every couple sentences. I remember reading a particular phrase that really blew my mind; “using widely available information and DNA they bought through the mail”. This might have just been me, but I was really surprised that people could buy DNA through the mail. How would you be able to package DNA? DNA is very small, and I just can’t see it arriving inside of anything large in the mail or anything, only a small envelope, no bigger than a dime, similar to what you may see on cartoons. On another note, I was also surprised to find out that mammals might not have ever been able to develop a placenta had it not been for viruses. I had never given much thought as to how placentas came to be, I sort of just thought that it was always there. Obviously, I wasn’t using my AP Bio knowledge. After reading how the syncytin used the same mechanism that retroviruses use to attach to the host cell, how biologists in the 70s saw a layer of retroviruses on syncytium in baboon placentas, and how the syncytium was the primary barrier between mother and fetus, I sort of got the impression of how mitochondria can be found in cells. It made me think that at some point in time, there was a symbiotic relationship (mutualism) between a retrovirus and the placenta (which resulted in engulfment, similar to what the endosymbiotoc theory proposes), which does not make sense, because viruses are essentially parasites. This might explain why I was so surprised about the connection between the placenta and retroviruses, but that might be a reach (I don’t think my brain could have thought about all that before actually thinking it through for a couple minute).

Overall, I was surprised that viruses could possibly benefit people. So far in my life, I’ve only heard about how viruses were bad, so it was nice to hear about viruses from a different perspective. It’s strange to think that they have played a role in mammals developing a placenta or that they have been in our genome for so long. Viruses have definitely been more beneficial to our survival that I had previously imagined.

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4 Responses to “Darwin’s Surprise” was full of surprises

  1. MichelleC says:

    I was also most surprised with the fact that we mammals might have developed placentas because of a virus. Human begins might still be laying eggs if we were not exposed to such a virus. I especially liked how you used your AP Bio knowledge of symbiotic relationships to deduce that there might have been such a relationship between a retrovirus and the placenta. We perceive viruses to always be threatening, yet this one virus could have made us who we are today. Placental development is a major characteristic for mammals, because it allows for the elimination of waste and the uptake of maternal nutrients we need to develop larger brains. I was also surprised when reading that endogenous retroviruses were found in the embryos of healthy chickens. Over time, will chickens no longer be laying eggs because of this virus?

  2. SamanthaO says:

    I couldn’t believe the part about mailing DNA out either. It sounds pretty cool and weird at the same time but also makes sense. Humans store and ship out the genome for viruses, why not DNA also? I think it’s just amazing to see how far we’ve come as a species and how technology has benefitted us so much. We’re able to see how viruses have altered DNA to the point that it helps us create and sustain life with the placenta. It just goes to show how much we really don’t know. Hopefully it pushes people to further research and see what other useful things viruses have done and could possibly do for us and other species.

  3. LiciR. says:

    That’s actually a really cool idea. I never would have thought about a symbiotic relationship between viruses and placenta cells. What you’re suggesting is a cool theory, but it could also be more like differential gene expression. Maybe a virus inserted itself into the genome (transduction??), became a gene, and was then activated/inactivated as needed. At any rate, I definitely agree with you: I’d never given much thought to placentas, and my mother is an OB/GYN!

    You also pose an interesting question: How is DNA bought online? Similarly, from where is it being obtained, and how long can it survive outside of a cell? It also brings up the debate of ethics, and how the buying/selling of DNA can be construed as unethical. Definitely calls for more research!

  4. DanielleY says:

    I was also surprised when I learned about how retroviruses were found on the placenta of mammals. I guess I’ve always thought that viruses could only be detrimental to an organism. Now that I think about it, just like how mutations are determined by the environment to be beneficial or detrimental, viruses could also be the same way. It probably depends on the situation and the environment.

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