Recent discoveries in the Laetolil beds at Laetoli in northern Tanzania have revealed hominid tracks made by three individuals in a bed of cemented volcanic ash. The tracks extend for a distance of 27 m and indicate a fully upright, bipedal gait with weight distribution similar to that of modern man. A single trail proceeds alongside a dual trail in which the footsteps of the leading individual are almost exactly overprinted by the second set of tracks. Radiometric dating of an overlying tuff has yielded a figure of 3.6 Ma. Stone artefacts are unknown in the Laetolil beds, and a date of ca . 2 Ma for the earliest formalized tool-making is postulated on the evidence from Olduvai Gorge.