Greetings to Tanya and Bongo!  Our alpha-weez, Yes, loves to play with
ping-pong and tennis balls, and has been grabbing them in her front paws and
scooching backwards with them (usually into a hidey-hole or play tube) her
entire life.  We were puzzled by this behavior until we saw a nature special
on mustelids.  During the segment on European polecats (domestic ferts'
closest cousins, genetically), the featured critter gathered a pile of
leaves in its front paws and scooched backwards into its den--your basic
den-lining behavior.  The domestic cousins still have this behavior
hard-wired in, it seems, and it is an efficient way for them to move smooth,
round objects they can't pick up in their mouths.  Hope this helps answer
your question.
 
Sally Childs-Helton and the Ferretopia Gang
Yes, No, Oz, Curious
[Posted in FML issue 1759]