tag:blogger.com,1999:blog-7583674511519808833.post1394251702098498547..comments2024-03-27T00:26:19.644+00:00Comments on Rosa Rubicondior: How Transitional Fish May Have Learned To WalkRosa Rubicondiorhttp://www.blogger.com/profile/06063268216781988588noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-7583674511519808833.post-11707577155842948372014-09-10T11:38:44.584+01:002014-09-10T11:38:44.584+01:00Very interesting to read - not only for creationis...Very interesting to read - not only for creationists. BTW: The transition from life in water to life on land was not easily attained. I can recommend some good articles describing this transition process more in detail. First an overview: http://www.learner.org/courses/essential/life/session4/closer2.html (about necessary adaptations to facilitate this transition from water to land).<br /><br />Then two articles full of intriguing details: 1) http://evolution.berkeley.edu/evolibrary/article/fishtree_09 (among topics discussed: What came first, gills or lungs?). And 2) http://evolution.berkeley.edu/evolibrary/article/evograms_04 (about the origin of tetrapods). <br /><br />By reading those three articles - together with Rosa's own here above - we also learn a lot about the phenomenon called exaptation, i.e. how shifts in the function of a trait during evolution occur (or with Rosa's words: "What this illustrates is a basic principle of biology - a developing organism is 'plastic' in that its environment changes the phenotype so the final organism is not simply an expression of the genotype."). <br /><br />Exaptation implies that a trait can evolve because it at first served one particular function, but subsequently it came to serve another. So what happened to the lungs among those fish having both gills and lungs? Well, some of them had their lungs transformed into a swimbladder - a gas-filled organ that helps the fish control its buoyancy. And conversely, both chick and human embryos go through a stage where they have slits and arches in their necks like the gill slits and gill arches of fish. (These structures are not gills and do not develop into gills in chicks and humans, but the fact that they are so similar to gill structures in fish at this point in development supports the idea that chicks and humans share a common ancestor with fish.)<br /><br />Read more about exaptation here: http://en.wikipedia.org/wiki/Exaptation .Helmer von Helvetehttps://www.blogger.com/profile/02136543309048013677noreply@blogger.com