From the CBC, a story of the pace of evolution. Millions of years required? Maybe not in some cases. I think the animals mentioned in the article illustrate the fact that subtle variations and mutations are taking place all the time. I think it's a testament to the wonders of evolution. Why, how.... does a fish adapt to PCB's? It certainly wasn't that way originally. Fascinating stuff IMHO.
Edit: I think I may have erred when I said the fish wasn't that way originally. What I mean is, there had to have been some fish resistant to PCB's when the toxin was introduced would there not? Or would the introduction of PCB's to the fish' environment spur the changes?