September 29, 2015

Homo naledi, a new species of human ancestor from South Africa

Homo naledi, a new species of human ancestor, found in South Africa.

Documentary by Quickfire Media 2015


In Autumn 2013, 2 cavers Rick and Steve found a new previously unentered chamber deep in Rising Star Cave near Johananesburg in South Africa. Lee Berger, a professor of palaentology at Witwatersrand University lead the research which revealed the bones were from early hominids.

There was a gap between known specimens of Australopithecus and Homo erectus, 2-3 million years ago. Australopithecus was an upright ape, with a smaller body and brain than Homo erectus which was more human like.

Lee Berger called for skinny scientists who could negotiate the narrow passages to the new chamber. Cams were set up throughout the cave, using more than 2 km of cable. The position of the bones was mapped by laser scanning.

In 2008 Lee Berger had investigated the nearby Malapa Valley. On 1 Aug 2008 his son had found a hominid clavicle in a rock at a small cave/hole in the ground. It was well preserved in the limestone layers and dated to 1.97 myo. It turned out to be a new species,  Australopithecus sediba. This discovery ended the gap between Australopithecus and Homo erectus. The bones were found to be from a female and a child. A complete skeleton was made by scanning and 3d printing. Tartar found on the teeth was tested and showed microscopic remains of many different plants such as grasses, wood bark and fruits. This indicates a diet similar to today's chimpanzees. It suggests that ape-like forest dwellers evolved into humans.

Back at Rising Star, the hip bones showed an upright but primitive gait. The jaws are more Homo-like. A piece of skull was definitely Homo and of a new species. Careful collection of the bones resulted in more than 2000 fragments from 12 individuals. This is the first new species between Australopithecus and Homo erectus to be found in abundance. The bones showed human-like feet, hands and teeth, which means they interacted with the environment. But the trunk and brain was more primitive, with chimp-like arms, long legs and a small brow. The tiny brain was only one third the size of a human bone. The legs and hands are part of our genus. But they are still close to Australopithecus.

There were no other animal remains in the cave. This is unheard of. Normally all 'human' finds are mixed with bones of animals. So how did these Hominid bones get into this deep, inaccessible chamber in Rising Star? It seemed to be a cemetery population. There were no signs of predation, no flow of material into the chamber, so were the bones put there? The brain is only slightly larger than that of a chimp, so could they have purposefully disposed of their dead? This would suggest highly advanced social behaviour.

This species could be an evolutionary experiment, as evolution went down many branches. It all adds to the story of our origins and fills in the gap at the start of our genus.

Shown on UK Channel 4 , Sept 2015 .


See my 2013 blog on the Rising Star expedition


And see more Australopithecus sediba on Wikipedia.


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