Two million years ago, people roamed the forests, hunted and gathered their food supplies. Their life was governed by the tropical climate of India. Hunting instilled in them special skills like quickness, alertness and skillful co-ordination.
Gathering food on the other hand, gave people the knowledge of distinguishing between edible and poisonous plants and also to pick regions for travelling where they can grow crops in the respective season.
There were reasons people had to lead a nomadic life like no knowledge of agriculture, exhaustion of food supplies available in the area they live in, search of water and prey, to meet relatives and due to the regional differences in the climatic and soil conditions which affected the plant growth.