I had one unlucky tribe. It was unlucky because I created it and then forgot that I created it... so... uh... oops. Poor things didn't even have a fire or anything. I created them and then I had to go take a phone call, so I closed the game... and then I just forgot. Now THAT is unlucky.

Most of my tribes are pretty lucky right now. They have an easy time because ten or more tribes have come before them and I know what I'm doing.