Panda cub Xiao Liwu was eager to play with a plastic ball during an exam last month. He made his public debut at the San Diego Zoo on Thursday. Ken Bohn/San Diego Zoo/AP hide caption itoggle caption Ken Bohn/San Diego Zoo/AP The Two-Way Agreed, Baby Pandas Are Cute. But Why? January 10, 2013 Xiao Liwu made his public debut Thursday at the San Diego Zoo. As fans crowded around the exhibit, hoping to catch a glimpse of the 5-month-old giant panda cub, we asked the question that perhaps needs no asking. Scientists offer some clues.