Ichnological research on Tibetan hominin hand and footprints and its indicative significance

Authors: Zhang, D.D., Bennett, M.R. et al.

Journal: Chinese Science Bulletin

Volume: 70

Issue: 10

Pages: 1329-1341

eISSN: 2095-9419

ISSN: 0023-074X

DOI: 10.1360/TB-2023-1219

Abstract:

Exploration of human ichnology began in the 20th century and significant advancements have been made in the 21st century. These imprints, including footprints and handprints, are invaluable resources for elucidating the evolutionary trajectories and living contexts of ancient human populations. Unlike traditional archaeological remains, such as human fossils, cultural layers, and faunal and floral remains, exceptionally well-preserved imprints can offer unique insights into aspects like muscle morphology, mobility patterns, gender distinctions, height, and ancient population demographics. On a global scale, noteworthy ichnological research includes analyses of hominin tracks found in volcanic ash in Tanzania, Africa (dated to ~3.66 Ma), footprints at White Sands National Park in New Mexico, USA (dated to 23–20 ka), and handprints discovered in Indonesian caves (dated to 51.8 ka). These imprints have significantly contributed to research on the evolution, migration, and behavioral cognition of ancient human societies. However, relatively little attention has been paid to the study of ancient human ichnology within China, and international investigations of imprints within travertine deposits are scarce. Since the 1980s, over 100 archaic human handprints and footprints have been discovered at different elevations within the multilayered sediments of the Quesang hot spring travertine, in the central Tibetan Plateau. This travertine is composed of calcium carbonate formed from the precipitation of CaCO3-supersatuated thermogenic water from the deep, underlying carbonate rocks and deposited at different elevations from 4043 m a.s.l. to 4270 m a.s.l. since ~500000 a BP. The archaic hominins intentionally and unintentionally pressed their hands and feet on the surface of the soft travertine that was recently deposited when the water emerged on the surface, after which the travertine was rapidly dehydrated to form trace fossils within the travertine beds. Evidence of 3D modeling and anatomic analysis indicates that they were made by the impression of hominin hands and feet when the travertine was in a soft state, and not by carving or the use of tools. Four groups of hand and foot traces are imprinted in laminated travertine layers at two locations from the top to downslope. The older traces were exposed by weathering/sliding of the overlying layer and were preserved under the arid climate and alkaline precipitation of Tibet. U-Th dating is currently the most dependable chronometric technique for dating the thermogenic travertine, after several dating methods were tested. Pure and dense travertine samples from different depths were selected for U-Th dating, and age modeling samples eliminated the possibility of ‘open system’ behavior by using stratigraphic and geochemical methods. The traces in Group 4 were dated to 187.7±9.6 and 207.3±9.3 ka BP, and those in Group 1, 2 and 3 were dated to between 9.2±2 and 6.6 ±1 ka BP. This remarkable discovery of hominin traces further demonstrates that ancient humans, possibly Denisovans, inhabited this Alpine hypoxic environment since the middle Pleistocene, and they represent the earliest artistic behavior within the archaic hominins.

Source: Scopus