Walking on four feet

Nobody knows when man began to walk on two feet. The biologists say the spared two hands(limbs)created civilization.As men are growing older and older,they will find it is harder and harder to walk on both feet.The animals teach them something.Maybe the most primitive way is the best way.(The pics here show the Blackstone Port(烏石港) in Yi-lan County where there are many cruisers waiting to bring the tourists to see the whales.)