LONDON.- From a rare dual-sex butterfly and an exciting new addition to the human family tree, to a striking electric-blue lobster and a new horned dinosaur, here are the top 10 favourite 2011 science and nature news stories from the Natural History Museum website. 1. Electric-blue lobster found in Billingsgate fish market, November The most popular story from 2011 was about a striking blue live lobster that was brought to the Museum for identification. 2. Ancient Denisovans and the human family tree, January The 2nd most popular story featured Museum human origins expert Chris Stringer talking about a new group of ancient humans and the research suggesting they interbred with us.