One hundred and fifty years ago, on May 30, 1863, young geologist Robert Bruce Foote bent down and picked up a stone tool on the Parade Ground at Pallavaram cantonment, near Chennai... It was a hand-axe made of a hard rock called quartzite. Prehistoric man had crafted it to dig out tubers and roots from the soil, butcher animals he had hunted and take out the meat, and so on. As Foote, then a 29-year old assistant geologist in the Geological Survey of India (GSI), cradled the hand-axe and looked at it transfixed, he recognised it to be a Palaeolithic...