Gene Loss as a Force of Evolution
The first thing that struck me as particularly interesting in the article about gene loss being part of evolution is how the author said that “thinking of gene loss as an evolution force is a counterintuitive idea.” To me, it wasn’t a counterintuitive idea until I actually thought about what I have been taught. When I first read this sentence, I immediately thought that, well yeah, of course losing genes can make you more advanced, because a) sometimes you have to lose genes to adapt to your environment, and b) sometimes a gene that you lose may actually be inhibiting some sort of advancement, and therefore losing it would be a step in the right direction in terms of evolution. Then I started to consider what the article was saying, and this led to me to two things. The first is the question, what counts as advancement? Becoming more complex? Adapting to your surroundings? If the latter counts, then even if a life form does not become more complex upon losing a gene, it would still become more advanced because it is better suited for survival in the specific climate, right? I hope that makes sense, because my brain is starting to confuse itself. The second thing I came to, when thinking back to what I have been taught, is the realization that the idea of becoming more complex when a gene is lost is indeed a counterintuitive one, as I have always been told that more genes usually means a more advanced life form. However, I found it very interesting that my first reaction was that losing genes can advance a life form.
The article talked about two ways a gene can be lost, and both contained (somewhat) familiar processes from Bio class. The first way a gene can be lost is physical removal. Transposition is an example of this, and it made me think of the corn lab, because it dealt with transposons in regards to the corn kernel color. The second way a gene can be lost is if the gene is not expressed due to mutations, which made me think of the mutations we learned about, like insertion, deletion, substitution, and inversion. Another point made in the article that reminded me of things I have learned was that losing genes can be beneficial to a life form. I saw this in my recent science fair project dealing with styrene, where I learned that we are better off if we don’t have the GSTT1 gene, because it breaks down styrene into styrene oxide, which is toxic and carcinogenic, and therefore damaging to us.
Of course, gene loss isn’t always beneficial. There are times when it is harmful, and there are times when it is neither harmful nor beneficial. The latter circumstance, according to the article, occurs when there are multiple genes that do the same thing present, and so even if a gene is lost, there is another one doing its job. The average human, in fact, has around 20 genes that don’t work, yet there is no negative impact. This makes me wonder why we have multiple genes doing the same thing in the first place? What is the point of having these “extra” genes? I don’t know if there is an answer to that question as of now, but I would like to look further into it.
Another question I had and would like to look into more is about gene loss contributing to a “new Y chromosome.” I’m not sure exactly what that means and how it works, but it sounds very interesting. I would love to have basically the whole paragraph containing that piece of information explained, as I didn’t understand it but would really like to.
In the book Full House by Stephen Gould, Harvard biologist Gould discusses your exact questions in your first paragraph. Gould goes into detail about how our society misguidedly measure complexity as a unit of success and superiority within the animal kingdom and beyond. Gould introduces the claim that the excellence of life is rather measured by its variety than complexity because it is the most diverse and adaptive species that survive. Gould makes the claim that the reality is that Humans are not the "most successful" creatures if one goes by this standard and that rather, microorganisms like bacteria are by far the most abundantly diverse and widespread living thing not to mention the simplest of living things, hence the most successful. He also goes into detail of how people view evolution as a progression, as if every living creature is constantly progressing towards an elite form of itself, from the ancient miniature horse to the gallant stallion of today, and the vine swinging monkey to the intelligent human to an eventual race of genius godlike beings. Gould argues that any progression we see is self imposed by us, that an animals evolutionary tract has no endgame rather is constantly shaping itself to whatever the world requires of it even if this means going backwards in evolution. For one he cites the Nannippus, an ancient tiny horse that evolved from a starting line of small horses, which evolved to greater size more like ours today, to the Nannipuss which actually shrank in size, appearing to progress backwards. It would appear that evolution is not linear, it is wibbly wobbly and simply goes with the flow.
ReplyDeleteThat is so interesting! I like that idea and will probably be thinking about the whole thing the rest of the day! Thanks so much for sharing!
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