News stories on using pets in clinical trials to test veterinarian drugs, debunking the Piltdown Man once and for all, and deciding just how smart crows can be, with David Grimm.   From the magazine It’s really difficult to figure out how old a free-living animal is. Maybe you can find growth rings in bone or other calcified body parts, but in sharks like the Greenland shark, no such hardened parts exist. Using two different radiocarbon dating approaches, Julius Neilsen and colleagues discovered that the giant Greenland shark may live as long as 400 years.   Read the research.   [Image: James Howard McGregor/Wikimedia Commons/Music: Jeffrey Cook]