Roll over! Fetch! Don't Grow Up! -- Pennisi 2007 (405): 2 -- ScienceNOW

Roll over! Fetch! Don't Grow Up! -- Pennisi 2007 (405): 2 -- ScienceNOW: "What's the difference between a tiny Chihuahua and an enormous Great Dane? When it comes to their size, the answer begins with a single gene. A gene hunt involving thousands of dogs reveals that small dogs all share a line in their DNA code that says 'be tiny.'"