What is the division of labor between brothers and sisters?

After the ape descended to the ground, he gradually got rid of the help of his forelimbs and walked upright with his hands and feet separated. In order to pick fruits, dig roots and catch some small animals as food, they use their forelimbs more, and sometimes they use branches and stones as "tools". These activities, at first, were just instinctive activities, and later in the long-term life process, they were repeated and became habits. Later, I gradually learned to hit another stone with one stone as a tool. It is in this long-term labor handed down from generation to generation that the forelimbs of ancient apes developed into human hands. "The hand is not only an organ of labor, but also a product of labor." At the same time, the hind limbs of ancient apes also developed into human feet.