19 December 2006

coincidental meetings and genetic mutations


I had the good fortune to run into two very unexpected people during my flight back from school just yesterday. The first was a good friend, with whom I volunteered for many hours each week last year, but haven't seen in months. The second was the conductor of the amazing orchestra I used to play with--I wasn't amazing, mind you, just glad to be in it--who I ended up, coincidentally, sitting next to on the flight home. It was the strangest but coolest travel experience in my life. I guess there are many reasons to explain coincidental meetings, for example, the homophily of social networks or the tendency for people who already know one another to participate in the same activities, and thus show up in the same places at the same time. It might also just be that I was in several airports during the holiday season when everyone travels. Anyway, it reminded me that the world is a very small place.

It also reminded me of the fateful meetings of the characters in Heroes, in which people from around the world collide together for unexpected reasons. Yes, I'm talking about a TV show (a damn good one). And that leads me to another thing that's been on my mind. Heroes, very similar in principle to X-Men, is about the possibility that many individuals around the world have genetic mutations that have allowed them to develop special abilities, like flight, spontaneous regeneration, telekinesis, among many others. These individuals are supposedly one step ahead in the evolutionary path for humankind. Anyway, all this mention of the human genome reminds me of an idea I was recently introduced to in biochemistry lecture. (Welcome to my random train of thought)

Of the 3 billion basepairs that comprise the human genome, only 1.5% is actually protein-coding genes. The rest? Unknown functions, intruding sequences that are never transcribed into proteins, and, by far the scariest, a huge portion of transposons. Transposons are mobile genetic elements, genes that can excise themselves and move to other areas in the genome spontaneously. By doing so, they often disrupt protein-coding sequences and cause deleterious mutations. The transposons in the human genome are generally inactive, but there is reason to believe that they once were active in our ancestors. The mechanism of the Type I transposon (the retrotransposon) is closely related to the mechanism by which retroviruses like HIV infect the body. They make a copy of themselves, and paste these copies in multiple places along the genome. These transposons, about 60% of the genome, may have been involved in an HIV-related virus that our ancestors carried. Now, they are merely the genetic burden we carry, a method to prevent the mixing of species. What would happen if they suddenly became active again, somewhere down the evolutionary line?

I'm pretty sure evolution progresses in the direction of survival, so that is probably an irrational fear. But I tend to have a lot of irrational fears, and this is just one of the most interesting.


At December 21, 2006 9:56 PM, Anonymous Ralphie said...

Um. I think this is called incoherence. Just kidding. Homophily is a pretty long word. Do you go to college? My landlord says he once went to college. I have to go outside now. Fields don't plow themselves. Love, Ralphie.

At December 29, 2006 4:00 AM, Blogger alisa said...

hey! I made a pretty bad attempt at making a blog. At least its a start...I really didn:t know what title to have so I got out of hand. Seriously, I don:t understand how you can manage to be so philosophical on your blog. I just want to ramble like I am doing right now...hehe. Well, gotta go eat dinner..

At February 26, 2007 11:41 PM, Blogger Kelley said...

This isn't philosophy it's just thought vomit :)


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