http://news.sina.com.cn/s/p/2010-03-23/142219923743.shtml can't really comment cuz i can't read chinese but damnnnnnn
It's almost seem like he had a twin at one point in the womb and than he ate his twin and that's the leftovers. >.>
they dont have a sure answer for that, just suggest it might be genetic change, whatever mutation it could be, virus, etc.