European anthropologists say the ancestors of modern man used their hands in much the same ways as their progeny much earlier than previously thought. The distinctly human ability to turn keys and grip a hammer are linked to two key evolutionary milestones: reduction in tree climbing and the rise of the manufacture and use of stone tools.
Researchers from the University of Kent (England), University College London, the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the Vienna (Austria) University of Technology found evidence Australopithecus africanus, the species represented by the fossil Lucy, used stone tools during its reign 2 million to 3 million years ago.
Matthew Skinner, senior lecturer in biological anthropology, and Tracy Kivell, reader in biological anthropology, both at Kent, examined the internal spongey part of the bone called trabeculae, which can change to reflect the actual behavior of individuals during their lifetimes, a press release said.
The researchers looked at both the trabeculae of human and chimpanzee hand bones and found clear differences. The differences were also present in known tool-making and land-bound species such as Neanderthals.
The research, published in this week's edition of the journal Science, indicates Australopithecus africanus had an opposable thumb and fingers adapted to tool use.
A study published earlier this month by researchers at the University of California, Berkeley, the University of Liverpool (England) and the Unversity of St. Andrews (Scotland) found hominins living 2.5 million years ago used sharpened rocks to butcher animals, an activity that led to the development of proto languages.
The study published in the journal Nature Communications, found found stone tools "weren't just a product of human evolution, but actually drove it as well, creating the evolutionary advantage necessary for development of modern human communication and teaching," lead author and postdoctoral researcher Thomas Morgan of UC Berkeley said in a press release.
The researchers taught 180 college students how to use Oldowan stone-knapping tools, which were used for some 700,000 years until hand axes and cleavers made their debut. They found a much higher success rate among participants who communicated with words rather than gestures.
"At some point they reached a threshold level of communication that allowed Acheulean hand axes to start being taught and spread around successfully and that almost certainly involved some sort of teaching and proto-type language," Morgan said.