Rats are social animals and much smarter than most of rodents (including squirrels). Trust me, my mother was behavioral biologist, and she experimented with both rats (black rats, Rattus rattus) and red (European) squirrels (Sciurus vulgaris).
I'll have to take the subject up with your mom, then. On the surface, at least, almost everything that squirrels do (from their manual dexterity to their nest building and food storage) suggests that they operate on a higher plane than rats.
