humans may have discovered complex, symbolic language in its present form about 60 thousand years ago, thereby initiating the development of knowledge in the modern mode. at these early stages, until the beginning of agriculture and village society some ten thousand years ago, human population were organised into largely autonomous-endogamous tribes of perhaps 2 to 10 thousand people each. there would be considerable social inter course within a tribe, but little across tribes, who would often speak mutually incomprehensible languages. there would then be common pools of knowledge limited to individual tribes; pools of different tribes may greatly diverge with little in common. however, even within tribes there may be people, such as shamans especially concerned with development and systematic management of knowledge, in charge of pools of specialised knowledge such as that of movements of celestial bodies or march of seasons, or of herbal remedies (gadgil 2001b).