Conclusion Just to clear the air, it is very true that you can do all the wrong things, keep your rat on pine, feed crappy food, etc... and your rat might live to be three years of age. I've certainly heard of it happening. And it is also very true that you can do all the right things with food, environment, and enrichment, and have a rat barely live to be two years of age. The biggest deciding factor on how long your rat is going to live, is genetics. If a rat has strong genetics, they are going to live a long time, even in not so desirable conditions, and if a rat has weak genetics, they are going to die young no matter what you do to make their life good. The thing to keep in mind, however, is that although there could be a rat kept in poor conditions that lives to be three years of age, if all the right things had been done for that rat, he/she might have lived to be three and a half or even four years of age. So love your rats and take the best care of them that you can. It may all seem complicated at first, but the more you live with your rats, the more experience you will gain. You'll be an old pro at rat care before you know it!