Recent exploration in Tibet has shown that humans penetrated the region between 13,000 and 15,000 years ago, and may have been there ten millennia before that. These foragers occupied short-term camps; permanent settlement did not occur until the Neolithic. "The Qinghai-Tibetan plateau is the largest continuous high-elevation ecosystem on the planet, characterised by extremes of climate," David Madsen notes in the Journal of Archaeological Science. "Understanding this is critical in understanding the capacities of early humans for the movement into other extreme environments such as Siberia and Beringia" — the Ice Age land bridge that led into the Americas.
     The team’s survey around Qinghai lake, in the northeastern corner of the plateau at an elevation of 3,200m (10,500ft), was at a lower elevation than most of Tibet, which lies above 4,000m, and formed an intermediate stage, they surmise, in human movement to high altitudes.
     Two sites on the south shore of the lake were studied: that at Heimahe No 1 consisted only of a hearth and four adjacent use surfaces defined by successive thin layers of charcoal. Radiocarbon dates for all four clustered between 13,000 and 12,800 years ago. The hearth was adjoined by an area of raked-out burnt cobbles, which may have been used for cooking. Such methods optimise the use of scarce fuel, something that must have been a problem in this treeless region, because the heated stones allow a longer cooking time and provide warmth during the cold nights. A slate scraper, a small grinding stone or anvil for smashing bones to extract marrow, a handful of bone splinters and some thinning flakes from tool manufacture were the principal artefacts found. "The limited cultural features and small number and diversity of artefacts suggest a short-term, single-visit foraging camp occupied by a small group," the team reports. The main activity was hunting a gazelle-sized animal and collecting birds’ eggs.
     The Jiangxigou No 1 site to the east along the shore consisted of two hearths, with debris from toolmaking and again the bones of a gazelle-sized animal. It has been dated between 15,000 and 14,000 years ago. "A comparatively large array of broken and burned bone fragments may be associated with boiling and degreasing," the team says, while four large cobbles may have been used to smash bones for marrow.
     The similarity of these sites suggest "a very consistent foraging and settlement strategy, occupation by a very small group for a very short, perhaps overnight, stay. This suggests that the Late Palaeolithic foragers of Qinghai lake were operating from residential bases located elsewhere, likely at lower elevations." Whether the lake area was exploited because of the availability of wild yak dung as a fuel is not yet known, but the overall impression is that these foragers did not adapt to living in the intermediate Tibetan uplands until after the ice had retreated and they were able to settle there as year-round herdsmen.

Source: Times Online (2 October 2006)