Human links to ancestors revealed

Washington: A new study has revealed human ancestors used their hands just as modern humans 3 million years ago. Pre-Homo human ancestral species, such as Australopithecus africanus, used human-like hand postures much earlier than was previously thought.

Anthropologists from the University of Kent, working with researchers from University College London, the Max Planck Institute for Evolutionary Anthropology in Leipzig (Germany) and the Vienna University of Technology (Austria), have produced the first research findings to support archaeological evidence for stone tool used among fossil ‘australopiths’ 3-2 million years ago.

The distinctly human ability for forceful precision (when turning a key) and power “squeeze” gripping (when using a hammer) was linked to two key evolutionary transitions in hand use: a reduction in arboreal climbing and the manufacture and use of stone tools. However, it was unclear when these locomotory and manipulative transitions occurred.

Dr Matthew Skinner, Senior Lecturer in Biological Anthropology and Dr Tracy Kivell, Reader in Biological Anthropology, both of Kent’s School of Anthropology and Conservation, used new techniques to reveal how fossil species were using their hands by examining the internal spongey structure of bone called trabeculae.

Trabecular bone remodels quickly during life and can reflect the actual behavior of individuals in their lifetime.

The researchers first examined the trabeculae of hand bones of humans and chimpanzees. They found clear differences between humans, who have a unique ability for forceful precision gripping between thumb and fingers, and chimpanzees, who cannot adopt human-like postures. This unique human pattern was present in known non-arboreal and stone tool-making fossil human species, such as Neanderthals.

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