Loss of tail is probably the useless change for the man in the course of evolution. The volume of cranial cavity and size of skull also increased in order to accommodate the large and complex brain. The modern man excels all other animals in intelligence. Erect posture of human beings is due to major changes in the muscle skeletal system. During the course of evolution of man, thumb (pollex) has been brought opposite to the fingers thus enabling the hand for better grasping power.