ScienceDaily: Less Is More, Gene Study Shows
It’s also possible that we humans lost some genes along the way, and those losses provided opportunities for changes that otherwise could not have occurred. For example, scientists have shown that over the course of evolution, humans lost a gene that produces a particular jaw muscle protein. Perhaps the loss of that gene gave us smaller jaw muscles, making room in our skulls for bigger brains.
あごの筋肉に関連する遺伝子を失ったために、頭蓋骨に脳が大きくなる余裕を持つようになったなど、チンパンジーとヒトの差は、何かを獲得したり突然変異したのではなく、失ったからではないかという説についての最新の研究。