Some species are altricial: born helpless and needing a lot of parental care and longer time to develop. Others are precocial: They must be quickly able to forage for themselves, keep up with the parents due to predators and other factors and are born at a more advanced stage. I'm thinking these spiny mice probably are precocial, have a longer gestation than regular mice but don't go through a pinky stage. I remember in Ecology class the example used was rabbits and hares, rabbits being the ones that are born blind and needing the parental care for a longer time. End of nerdy science discussion! Anyways they're very cute.