From the most recent Seed Magazine, which you should be subscribed to:One element common to both human and fugu is a DNA sequence called LINE, short for Long Interspersed Element. LINE, itself a gene about 6,000 base pairs long, codes for an enzyme called a reverse transcriptase. The key here is that it recognizes its own RNA sequence, and repeatedly inserts copies of itself into our genome. LINEs seem to be relics of the "copying machinery" of old viral infections wherein a virus would embed a portion of itself into our genome, not enough to propagate the full, infectious virus, but enough to continue copying itself. It is a classic example of a selfish gene: It has no purpose but to do only that, without benefit to us. If you're reading this, you probably already know Dr. Myers' blog Pharyngula, but if not, you should be reading it. This is a fantastic article, very detailed and intricate, but completely understandable to newbies in the biological sciences. The moral of the story is clear: not only are we the result of a long and complicated evolutionary process, but we have old DNA that clearly marks our relation to some of our oldest ancestors, including virus-like species.
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