Yea. But no on the squirrels/rats comparison.
Squirrels are hard wired to eat. It’s the thing that they think about the most.
Rats, like many animals, are hard wired to reproduce. It’s the one thing they think about the most.
As with everything there are exceptions. Humans, generally are sex driven but asexual humans also exist. Dogs, generally are sex driven but some black labradors have a genetic mutation that makes them food driven like squirrels.
So generally, a squirrel’s mission in life is to eat and store food. Generally, a rat’s mission in life is to make more rats.