If you grew up with dogs (as I did), you know that something bizarre and sad often happens when a mother dog loses her puppies. With hormones and maternal instinct coursing through her, she will frequently adopt inanimate objects as “replacement-puppies.” Usually, she chooses something like a boot, hat, or stuffed toy. Mother cats do the same thing, typically with socks. Whatever the object, the animal will carry it around, lick it, attempt to suckle it, protect it, and otherwise pour all of her energy and nurturing instincts into it—often for much longer than she would an actual litter of puppies or kittens. Something in her brain is soothed by the non-living replacement, but ironically, this replacement-puppy can prevent the mother from trying again to bear actual young. Her instincts are permanently misdirected, wasted on an object that will never be her real offspring.