Homo habilis evolved from australopithecines

Smarter than Homo habilis?

The versatile hand of the Australopithecus sediba is a better candidate for first hand tool making

Hand bones, which can be assigned to a single individual and clearly classified taxonomically, are rarely found in the hominin fossil record. An international research team led by Tracy Kivell from the Max Planck Institute for Evolutionary Anthropology in Leipzig describes in a current study the oldest and most complete hand of a hominin after stone tools appeared, the hand of a 1.98 million year old Australopithecus sediba from Malapa, South Africa. The scientists found that Au. sediba still used his hands to move about in trees, but at the same time already had the ability to use the human precision grip, a prerequisite for tool manufacture. The hand of Au. sediba is therefore a better candidate for an early toolmaker's hand than that of Homo habilis. It could later become the hand of other hominins of the species homo have developed.

The extraordinary abilities of the human hand are considered to be one of the hallmarks of modern man. In the course of evolution, the human hand no longer began to serve as a means of locomotion and was now primarily devoted to handling objects, such as the use and finally the manufacture of tools. Research into the functional evolution of the human hand has so far been hindered by the fact that only a small number of completely preserved hand skeletons existed, each of which could be assigned to an individual and reliably classified in the hominin family tree.

Tracy Kivell from the Max Planck Institute for Evolutionary Anthropology in Leipzig and her colleagues from the University of the Witwatersrand in Johannesburg, South Africa, Duke University in Durham, USA, and the University of Zurich, Switzerland, now describe the oldest in their current study and most complete fossil hand of a hominin. It is younger than the first documented stone tools, which are around 2.6 million years old. The fossil remains come from an adult Au. sediba Woman from Malapa in South Africa and included an almost complete right hand, a right arm and various bones of the left hand. “Almost all other fossil hand bones of hominins that are older than the Neanderthals are isolated bones that are not anatomically connected to each other (that is, they do not belong to the same individual) and cannot be clearly assigned to a specific species "Says Tracy Kivell:" This one Au. sediba Hand now enables us for the first time to examine the functional morphology not only of individual bones but of the entire hand of a hominin older than a Neanderthal. ”

The scientists reconstructed the Au. sediba Hand, compared them to other human fossils and then examined them for special features associated with the precision human grip and ability to make stone tools. They found that at Au. sediba many of these features are present, including a relatively long thumb in relation to the other fingers, which is even longer than the thumb of a modern person and the Au. sediba Thumb-finger precision grips facilitated. Au. sediba In addition, it has more features associated with the manufacture of stone tools than the 1.75 million year old "OH 7 Hand", which was originally used to identify the Art Homo habilis, the “skillful person”. The Au. sediba But hand also has morphological peculiarities that suggest that it could be bent sharply, a prerequisite for climbing in trees.

“All in all, we conclude that Au. sediba still used his hands to move in the trees, but at the same time was already capable of human-like precision grips ”, says Kivell and adds:“ Compared to the hand of Homo habilis has the Au. sediba Hand over the better conditions for tool manufacture. It is a more likely candidate as a starting point for the evolution of the modern human hand. "