We were "gifted" two male gerbils over 4.5 years ago (by Grandma for the children when Grandad died as some sort of weird compensation 
). Google claims they live for 3 years. I'm trying hard not to wish them away, but no one particularly likes them, they smell and make a mess, cleaning them out is tricky (just catching them is a job of work) and they are just another thing to think about. I have 3 young-ish DC, a full-time job and an incapacited DH - we wouldn't choose to have pets as we cannot give them proper attention or care. I am doing my best for these creatures - they are our responsibility, and didn't ask to live with us. I'm not sure about the ethics of the second-hand gerbil market, and it would probably upset Grandma, so they are probably here for the rest of their natural lives. But any ideas how long that may be?