Genetically Poor Predators (except when it's a squeaky toy)

I was doing dishes this afternoon with the patio door open and the dogs puttering in and out, when I realized it'd been awfully quiet for a while.  I went into the backyard to investigate and found Daisy fussing over something in the grass.  It was a dead mole, its wet fur plastered to its fat little body on one side.  Once Daisy saw that I was just a passive observer, she went back to what she was doing: nibbling at its fur, then pawing at the mole and thrusting at its body with her nose.

Why didn't she eat it?  If she was playing with it, why didn't she rip it open and pull out all the innards, like she spends hours doing with her stuffed toys?

Ray Coppinger, in his book Dogs: A Startling New Understanding of Canine Origin, Behavior, and Evolution, says that perhaps our domestic dogs have lost part of their genetic code, the part that says "chase prey, then grab prey, then bite prey, then eat prey."  More or less.  He postulates that certain elements of the sequence have been added or lost, depending on what humans wanted dogs to do.  For example, what good is a retriever that retrieves a half-eaten duck?  Not much...  Thus, hunters bred retrieving dogs who would "chase, grab" but not "bite, kill, eat."  Border collies and other herding dogs have a special sequence of genetic code that says "eye-stalk, chase," the eye-stalk being that special lowered-head glare they use to intimidate the flock.

So what does that mean for Daisy?  Maybe that, as a (very) mixed-breed dog, she's retained the entire predatory sequence...except for "eat"?

But why, then, does she rip apart (essentially, play-eat) her stuffed toys?  One answer might lie in the sometimes-bizarre, sometimes-hilarious area of genetic drift.  Some genes get passed on kind of accidentally--that is, by chance--not because they help the animal survive or procreate, or do much of anything important.  This phenomenon is what causes dogs to spend an inordinately long time scratching a "nest" in a smooth couch cushion before laying down.  It would make sense in a pile of leaves, grass, or snow, but what the heck good does it do on the couch?  It's just a mostly-useless genetic remnant of a behavior that used to be very important, maybe even life-saving, to dogs (or wolves, or a missing link between them), but nowadays doesn't hurt (or help) dogs' chances for survival.

We're still anxiously awaiting a lot more research in the field of dog behavior.  At this point, it's hard to say much for sure.  Except rest in peace, Mr. Mole.  And Daisy: please don't lick my face for a couple of hours.