Dec. 13, 2012: Like a human toddler, the 14-pound Xiao Liwu is incredibly curious and all over the place. Wet and muddy from his morning excursions with Mom, the cub crawls rambunctiously over the tree limb veterinarians have put out for entertainment.

During this 17th exam, vet Tracy Klippinger tests the bear's neurological development by holding his back legs off the ground to see if his front legs would continue to move forward, then the reverse. Combined with tracking the doc's fingers with his eyes, baby boy passes with flying colors.