Reincarnation... thoughts? *UPDATE*

I just asked about aliens and got a few answers and it seems just about everyone agrees that humans cant be the only living creatures in the universes. I now would like to know everyones thoughts on reincarnation and lets put religion to the side. I'm Christian but I'm still very open to the possibility of reincarnation as for some reason I have the never ending feeling that I'm going to do it all over again("it" being childhood). So, I'd like to see how others feel and what they believe.

I'd like to add to my question, if you do believe in reincarnation do believe that humans can only live human lives or a dog could only be a dog and so on? Or do you believe that a human could become a frog or hippo or anything and vise versa?