Used to be cute and little

Just because now they are huge doesn't mean they were always. At one point they used to jump from tree to tree using it to grab branches.

Given a few evolution'sevolutions they now live on the ground and use their tail to create nests.

Given a few evolution'sevolutions and an ice age: They now grew to be much bigger to beand able to put on the pounds of fat and fur needed to survive long cold nights. They're tail was now used to find and dig out food from the snow and ice.

Evolution happens again (does it ever stop???): It now knows to throw things.

Fast forward: They throw rocks at walls and collect the sharp pieces. Hunting/Foraging is now much easier. Brains gets bigger.

Blink: Fire can now be created at whim.

Blink: Farms now start.