It looks like all of the old evolution threads have been locked, so I thought I'd start a new one based on a discussion of types of evidence that support evolution. If someone finds an old thread to resurrect, I'll gladly move to that one instead. Typically, evolution is such a slow, gradual process that it can be very difficult to document it actually happening. But sometimes we happen to stumble upon some significant findings. [link=http://news.nationalgeographic.com/news/2008/04/080421-lizard-evolution.html]Lizards Rapidly Evolve After Introduction to Island[/link] [hr] In just a few decades the 5-inch-long (13-centimeter-long) lizards have developed a completely new gut structure, larger heads, and a harder bite, researchers say. ... Genetic testing on the Pod Mrcaru lizards confirmed that the modern population of more than 5,000 Italian wall lizards are all descendants of the original ten lizards left behind in the 1970s. ... Researchers found that the lizards developed cecal valves?muscles between the large and small intestine?that slowed down food digestion in fermenting chambers, which allowed their bodies to process the vegetation's cellulose into volatile fatty acids. "They evolved an expanded gut to allow them to process these leaves," Irschick said, adding it was something that had not been documented before. "This was a brand-new structure." Along with the ability to digest plants came the ability to bite harder, powered by a head that had grown longer and wider. The rapid physical evolution also sparked changes in the lizard's social and behavioral structure, he said. For one, the plentiful food sources allowed for easier reproduction and a denser population. The lizard also dropped some of its territorial defenses, the authors concluded. Such physical transformation in just 30 lizard generations takes evolution to a whole new level, Irschick said. It would be akin to humans evolving and growing a new appendix in several hundred years, he said. [hr] This is actually an amazing find. While it's still uncertain whether this can be classified as a conclusive example of speciation, it is still very good documentation of evolution and adaptation in action.