The differences are what interest me, because the one on the left was made to a pretty unvarying design for about a million years -- from one-and-a-half million years ago to half a million years ago.
让我感兴趣的是差异性。 因为大约1百万年-- 从150万年前到 50万年前，左边的手斧基本没有做任何改变的设计。