2 million year old possible human ancestor reconstructed

Australopithecus sediba, reconstructed from the bones of three individuals.

The two-million-year-old remains of several partial skeletons belonging to a previously unknown humanlike species were found in 2008 near Johannesburg. A new analysis shows this species – Australopithecus sediba – had a human-like pelvis, hands and teeth, and a chimanzee-like foot.  The findings appear in Science journal.In six separate research reports, scientists probed further into the anatomy of a juvenile male skeleton, commonly referred to as MH1, a female skeleton, known as MH2, and an isolated adult tibia or shinbone, known as MH4.

The specimens were found at Malapa in the famous Cradle of Humankind World Heritage Site, just to the northwest of Johannesburg. They were pulled from a pit – a depression left in the ground by a cave complex that lost its roof through erosion. Researchers think the female and male could have been mother and son.

It seems they died together in some tragic accident that saw them either fall into the cave complex or become stuck in it. After death, their bodies were washed into a pool and cemented in time along with the skeletons of many other animals – sabre-tooth cats, hyenas, antelope, even birds and mice.

The individuals from Malapa fall within a broad group known as the australopithecines, upright-walking humanlike creatures that roamed Africa between four million and two million years ago.

An analysis of Au. sediba‘s lower limb anatomy by Jeremy DeSilva from Boston University and colleagues suggests that the species walked in a unique way. Its small heel resembles that of a chimpanzee more than it does a human. This suggests it likely walked with an inward rotation of the knee and hip, with its feet slightly twisted.

This primitive way of walking might have been a compromise between upright walking and tree climbing, the researchers suggest, since Au. sediba seems to have had more adaptations for tree-climbing than other australopithecines.

More here: http://www.bbc.co.uk/news/science-environment-22108784

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Developing lithic techniques may indicate growth in intellectual capacity

Developing lithic skills may show developing intellect.

Los Alamos National Laboratory Fellow Giday WoldeGabriel and a team of Ethiopian, Japanese, American and German researchers have examined the world’s oldest handaxes and other stone tools from southern Ethiopia. Their observation of improved workmanship over time indicates a distinct advance in mental capabilities of the residents in the region, they claim, with potential impacts in tool-development skills, and in overall spatial and navigational capabilities, all of which improved their hunting adaptation. “Even though fossil remains of the tool makers are not commonly preserved, the handaxes clearly archive the evolution of innovation in craftsmanship, acquired intelligence and social behavior in a pre-human community over a million-year interval,” said WoldeGabriel. The scientists determined the age of the tools based on the interlayered volcanic ashes with the handaxe-bearing sedimentary deposits in Konso, Ethiopia. Handaxes and other double-sided or bifacial tools are known as the first purposely-shaped tools made by humanity and are closely associated with Homo erectus, an ancestor of modern humans. A paper in a special series of inaugural articles in the Proceedings of the National Academy of Sciences, “The characteristics and chronology of the earliest Acheulean at Konso, Ethiopia,” described their work. Some experts suggest that manufacturing three-dimensional symmetric tools is possible only with advanced mental-imaging capacities. Such tools might have emerged in association with advanced spatial and navigational cognition, perhaps related to an enhanced mode of hunting adaptation. Purposeful thinning of large bifacial tools is technologically difficult, the researchers note. In modern humans, acquisition and transmission of such skills occur within a complex social context that enables sustained motivation during long-term practice and learning over a possible five-year period. Making the right tools for the job Researchers observed that the handaxes’ structure evolved from thick, roughly-manufactured stone tools in the earliest period of Acheulean tool making, approximately 1.75 million years ago to thinner and more symmetric tools around 0.85 Ma or megaannum, a unit of time equal to one million years. The Acheulean is a stone-age technology named after a site in France where handaxes from this tradition were first discovered. The chronological framework for this handaxe assemblage, based on the ages of volcanic ashes and sediments, suggests that this type of tool making was being established on a regional scale at that time, paralleling the emergence of Homo erectus-like hominid morphology. The appearance of the Ethiopian Acheulean handaxes at approximately 1.75 Ma is chronologically indistinguishable from similar tools recently found west of Lake Turkana in northern Kenya, more than 125 miles to the south. “To me, the most intriguing story of the discovery is that a pre-human community lived in a locality known as Konso at the southern end of the Ethiopian Rift System for at least a million years and how the land sustained the livelihood of the occupants for that long period of time. In contrast, look at what our species has done to Earth in less than 100,000 years – the time it took for modern humans to disperse out of Africa and impose our voracious appetite for resources, threatening our planet and our existence,” WoldeGabriel said.Read more at: http://phys.org/news/2013-03-ancient-stone-tools-pace-remarkable.html#jCp

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