Growing up, my brother and I had to gradually overcome the resistance of our parents to the idea of having a pet in the house.  We did this by working our way up the food chain, starting with goldfish, toads, turtles and eventually getting as far as gerbils by the time I went off to college.  One major problem with all of these pets is that they were not really capable of being social with predatory creatures a hundred times their body mass.  Go figure.

The one really social gerbil we had, the one with complete comfort with all of us, made the mistake of running under my foot as I took a step backward.  Trauma ensued, but evolutionary logic asserted itself once again.