Opposable thumbs, cranial size, altruism and cooking all played a part, but central to the naked ape's success was its ability to dominate other species.
A good rule of thumb is 13 calories per pound of body weight for a sedentary person of either sex, 16 calories per pound for a moderately active person, and 18 calories per pound for a vigorously active person.
Let me show you. Look, at first place both sticks between the thumb and the fore finger, then, keep one still and move the other, so as to make them work like pincers.
It also watches for what's called 'close-by hands', where both hands are close together near the top of the wheel, so the driver can type with both thumbs and drive at the same time.