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.... you know that leeches are used in modern medicine, right? Not for bloodletting, but many of the contexts that leeches were used for have enough overlap with bloodletting that it's actually best to assume that folks actually did use leeches to good effect. The core of this ongoing debate is mainly about some regions, like Alu, which appear to truly have no function, and have little to no functional effect. I think scientists could still make a good faith experimental effort at attempting to salvage this idea, see Eddy's proposal about a "neutral genome" here: https://www.cell.com/current-biology/comments/S0960-9822(13)... The fairest way to describe it is that scientists continually find that more and more DNA that was neglected as having zero functional (no observable, measurable, directed activity that is under evolutionary selection pressure) effect, does indeed affect the fitness of organisms in ways that are not accomodated by existing theories of gene expression or regulation. It seems unlikely, however, that we will ever truly be able to point to every single base pair in teh genome and say "it's under functional pressure", and if that's the case, it's easy to make the argument that some of it is "junk". However, complex information processing systems like life don't really fall into simple classification, "junk" is really a subjective term, we should focus instead of measurable scientific phenomena like fitness. |
Today, we still use leeches but only for those cases where they can provably affect the cause.