This study aimed to pinpoint the genetic changes that led to hind limb loss, and discovered a drastic change that inactivated a gene essential for limb development called, and I'm not joking, Sonic hedgehog or Shh.

这项研究旨在找到导致后肢消失的基因变化。他们发现了一个使对四肢发育很重要的基因失活的重大变化，我没开玩笑，这个基因叫做音猬因子。