tag:blogger.com,1999:blog-2862170131521435894.post4341355413368889313..comments2023-11-02T07:39:02.009-07:00Comments on Post-Modern Enlightenment: Feathered Dinosaur Fossil = Boneheaded CreationistsUnknownnoreply@blogger.comBlogger2125tag:blogger.com,1999:blog-2862170131521435894.post-54417771968407985262012-04-24T10:31:45.518-07:002012-04-24T10:31:45.518-07:00"It just further backs up my notion that the ..."It just further backs up my notion that the development of an embryo from a single-celled organism up through to a complete organism is a replay of evolution."<br /><br />This is an old idea, going back to at least the 19th century, and is known by the catchphrase "ontogeny recapuitulates phylogeny."<br /><br />It turns out to not be true--it gets cause and effect exactly backwards. What turns out to actually be going on is much more interesting, and the booming field of evo-devo biology is all about it. What they've found is that evolution frequently operates by altering development--it does not create new structures so much as alter the ways in which existing structures develop. So, for example, rather than a series of mutations that erased the forelegs of our quadrapedal ancestors and replaced them with a whole new set of genetic instructions for building arms, there was a much smaller set of mutations that altered the way fundamentally the same bones grow, so that they end up as arms rather than forelegs. Put another way, evolution rarely writes when it can edit.<br /><br />The result is that there is a stage in development at which all vertebrates look similar, because most of the differences between their developmental processes have not started yet. This does not mean that we have an ancestor that looked like a pharyngula, just that we have common structures with our relatives before development adds in variation.<br /><br />"Somewhere inside of your chicken or turkey is the DNA to resurrect Velociraptor"<br /><br />No, it's really not. Evolution is not "building blocks on top of building blocks," and genes are not Legos. Even assuming turkeys are directly descended from a Velociraptor (which there is no reason to assume they are), many of the genes of that Velociraptor have been altered by mutations in the interceding generations. True, many of the ancestral dinosaur's genes probably are still there, but there is no way of knowing which until we check.<br /><br />Spot on with the critique of the idiot creationists, though.Froborrhttps://www.blogger.com/profile/08782366056731381450noreply@blogger.comtag:blogger.com,1999:blog-2862170131521435894.post-35455146927256794902012-04-09T04:18:29.517-07:002012-04-09T04:18:29.517-07:00How do the Creationists get away with it?How do the Creationists get away with it?Simon J Broomehttps://www.blogger.com/profile/07707363083219631570noreply@blogger.com