Several years ago there was a brutally cold winter. At the stable where we kept our horses, the animals always cooperated with one another. For example the cats would crawl up the side of the stalls and jump on the backs of the horses (who were wearing stable sheets) to sleep in order to steal some heat on the cold nights. But this one cold snap brought a whole new level of cooperation. You see the mother cat and the mother dog both has litters around the same time. Due to the extreme cold, the mother cat moved all of her kittens into the puppy nest. From there the mother cat and the mother dog took turns sitting on the nest to keep everyone warm while the other parent was out hunting or eating or whatever. It was miraculous.