Bit of a random question, but curious. Would it be possible to cross a Polar Bear with the Brown Bear? Clearly, they would never meet under any sort of natural conditions, so it may well be that there has been too much of a genetic drift from one another, to have a successful litter of cubs. Or maybe not. Maybe the genetics would be fine, but the practicalities would be a problem. I have a feeling that the whole bear mating thing would be pretty aggresive between two bears of the same species, let alone two of different species - would they even be interested in mating, would they more likely fight? Again, I suppose it could be done through semen extraction, and impregnation, that would probably be the most feasible of all. Of course, both species do inhabit vastly different terrain, so it would be interesting to see what sort of habitat and food the cubs inclined toward?