Birthday wishes to Riff Raff from my horde! Re altruism in rats; I've read this article previously and agree that it's not proven what the motive is; I think they would've learned something more if they'd given the rats the chance to leave the room, as it were! I know they can be nice to cagemates, i.e. witness an elderly rat using someone else as a pillow and that rat seeming quite content to be at his disposal. But share, my guys absolutely don't! My best, albeit rather gruesome example, is when Nikita caught a mouse (when I found him, the evidence was almost gone) and was dashing about, desperate to stop his cell-mates from snatching his treat.

I'd also like to know if these were rats known to the rat freeing him or her, because in my experience any sort of altruism or kindness is only within their established group (mischief). They're indifferent or hostile to outsiders.