Blog dedicated primarily to randomly selected news items; comments reflecting personal perceptions

Friday, September 11, 2015

Homo naledi [Lesotho for 'star']

"It was soon apparent that what I thought was an individual skeleton was dozens of individuals."
"With every bone in the body represented multiple times, it is already practically the best-known fossil member of our lineage."
"It's enormously surprising to see a very primitive member of the genus [Homo], not very humanlike overall, to do something unique to humans. To see it in a small-brained hominid is completely surprising. None of us expected it."
"[H.naledi] comes near or at the root of the genus Homo] in excess of 2.5-million years ago."
Lee Berger, paleoanthropologist, University of the Witwatersrand, Johannesburg

"One of the most exciting things for us is we discovered something new in biology. We had never seen a creature like this before."
"H.naledi is unlike anything in our genus.... When you look at the anatomical elements across the body, it's an enormous assemblage of fossils. The task was to interpret these fossils and put them in the context of evolution and where they fit on the human tree."
"We have 190 teeth, and they are represented multiple times. We have more than a dozen molars, and the differences are typically less variable than in small populations of humans. Every member of every team ... agreed we were looking at the same species. The hand may be telling us a different story than the shoulder, but it would beg belief that we mixed things [belonging to different species]."
"This is an anatomical mosaic that evolutionary history gave us ... it gives us a different model for how things could fit in our own origins."
"This chamber has not given up all its secrets."
John Hawks, anthropologist, University of Wisconsin, Madison, U.S.A.
While primitive in some respects, the face, skull, and teeth show enough modern features to justify H. naledi's placement in the genus Homo. Artist Gurche spent some 700 hours reconstructing the head from bone scans, using bear fur for hair. National Geographic
The Cradle of Humankind World Heritage Site located in South Africa, given its name, is just the very place where you might expect to find ancient archaeological sites that might hold bone remnants of creatures who lived in the area in prehistoric times. It isn't called the 'cradle of humanity' for no reason. The places where primordial creatures once lived and roamed have changed as the geology undergoes variations in its original natural layout, yielding to the curious now and again proof of early hominid ancestors of modern humankind.

It takes nerve, experience and determination to enter tunnels deep in the Earth to discover caverns in the dark, close confinement of the bowels of valleys and forests that once hosted creatures long since extinct; the paleolithic record reveals to scientists answers to some mysteries the details of which can sometimes be deduced by informed research in hopes of fully understanding the long slope of evolutionary transformation from the primitive to the developed present.

It took the adventurous spirit of two amateur caver/spelunkers undeterred by smotheringly-close confines in narrow winding tunnels as dark as total absence of light can ever be, to find at last a difficult-to-reach chamber within which could be found natural artifacts proclaiming the presence, millions of years ago, of ancient creatures predating the evolution of modern man. Imagine narrow passages through which stomach-crawls are the only form of advance; stone walls, narrow ledges and a sideways-accessed descent of 122-metres.

And then the destination reached, a nine-metre-long cave of a chamber estimated to be between two million and three millions years old. And within, fossil fragments of a distant relative of the human species; a cache of bones and teeth stuck in ancient clay; some 1,500 of the objects representing the largest such fossil discovery ever discovered in Africa, the cradle of humankind. Two years of analyzing by specialized international experts followed the month-long excavation of the fossil find.

And then a joint announcement by National Geographic and the South African Department of Science and Technology/National Research Foundation and the University of the Witwatersrand, of the spectacular find in the Rising Star cave complex about 40 kilometres northwest of Johannesburg. The bone fragments have not been dated yet, but the involved scientists feel they may represent the most primitive members ever found of the genus Homo. All of the fragments of men, women, children and infants appear to have been ceremonially placed in the cave following death.

H.naledi, explain the scientists, had a brain the size of a baseball with shoulders and torso primitive in design, long, curving fingers for climbing and swinging from trees, but with wrist bones that indicate H.naledi used tools. Legs and feet almost indistinguishable from those of modern man gave it the strength and balance to walk [bipedally] upright and travel for long spaces of geography and time. It took 21 days in November of 2013 to secure the fossils by a team prepared to take part in a major excavation under physically trying and dangerous circumstances.

Six volunteers were chosen to take part in the excavation, all of them women, who had to be slender in fit into the narrow confines of the tunnels, and experienced in the technical side of the work. Two papers are set to be published about the discovery, in the open-access scientific journal eLife. The National Geographic Society features the discovery of H.naledi in next month's magazine cover. Dawn of Humanity, a special by National Geographic and Nova premieres on television on PBS, and will be available via online streaming.

The fact that the fossils weren't fused into rock which can be carbon-dated, will make it difficult to determine the age of the fossils. More research needs to be conducted to fully determine all the details involved in validation of informed hypotheses. What does appear undisputed however, is the confidence with which H.naledi is being recognized as humanity's far distant predecessor.

Sunlight falls through the entrance of Rising Star cave, near Johannesburg. A remote chamber has yielded hundreds of fossil bones—so far. Says anthropologist Marina Elliott, seated, “We have literally just scratched the surface.” Photo: National Geographic

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