A team of alien researchers get bored one day, and decides to conduct an experiment.
Seeing that the great ape Homo sapiens sapiens turned out so well ( in terms of technological development and ecological domination ) on earth , they wonder if any other family has the capacity for the same. So they take every animal that existed at the beginning of the anthropocene, divide them into groups, and then place them on synthetic planets , containing a variety of other animals dependent on which group was there. On a certain planet , they put every variant ( for maximum genetic diversity ) of mouse and rat , rats on one side of the planet , mice on the other. The same land-to-sea proportions that exist on earth are on that planet , and so do all the biomes. Of each variant , they put 10,000 breeding pairs, give them a temporary surplus of water and food, and set the timer. The scientist assigned to this planet decide to first work on freeing up the mice's hands to facilitate the creation of tools.
The Essential Question: what are some environmental pressures that might force rodents to walk and or run erect?
Alternate Essential Question: what are some environmental pressures that might force rodents to gain prehensile hands?
( please answer one or the other, but if you feel like answering both , that is just as welcomed )