Tuesday, 14 February 2012

Another look at the Canteen Kopje Skull.

The Canteen Kopje Skull was unearthed in 1929, by a prospector named Kenneth Kemp, who was sifting the Vaal River gravels for diamonds at Klipdrift in Northern Cape Province, South Africa (river gravels are a good place to look for diamonds, since erosional processes that destroy less durable minerals can concentrate them relative to their original deposits). It made its way to the McGregor Museum in Kimberly, where it was described in a paper in the journal Nature by Robert Broom, the Keeper of Vertebrate Palaeontology at the South African Museum in Cape Town.

A modern visitor posses with the Canteen Kopje Skull. Tripadvisor.

Broom described the skull as being of great antiquity, due to its heavy mineralization. He furthermore noted that it lacked a lower jaw or teeth, a sign, he felt, that it was not a burial, but a skull that had been interred in the Vaal River deposits by natural means, though he noted the presence of 'limb bones' which would be highly unlikely (from the viewpoint of a 21st century palaeontologist) to survive natural interment in a fast moving river environment (sluggish rivers do not shift gravel), or reworking from a more stable environment. The gravels at the Canteen Kopje sight are thought to be Late Pliocene to Pleistocene in age, and have not yielded any other bones. At the time interest in the study of early man in South Africa was growing, and the skull was assigned to a race of humans known as Boskop Man, that were then thought to have roamed pre-historic South Africa, but are now regarded as mythical; the bones assigned to Boskop Man are slowly being re-assigned to other human groups.

In a paper published in the South African Journal of Science on 16 January 2012, a team of scientists led by Patricia Smith of the the Laboratory of Biological Anthropology and Ancient DNA at the Hadassah Faculty of Dental Medicine at the The Hebrew University of Jerusalem describe a re-examination of the Canteen Kopje Skull, and the conclusions drawn from it.

Smith et al. examined the current setting of the Canteen Kopje Skull, which has been set into a plaster reconstruction of Boskop Man, and coated with (now chipped and discoloured) shellac, and came to the conclusion that it would not be possible to remove the skull fragments from the plaster matrix without risking damage to the delicate skull. They also noted that the skull showed signs of having received a fairly serious injury in life, but had apparently recovered, something that Broom apparently overlooked.

The Canteen Kopje Skull, as reassembled by Robert Broom. Arrow points to the healed injury. From Smith et al. (2012).

Faced with this problem Smith et al. decided to examine the skull via computerized X-ray tomography (CT scans). Based upon these scans they could find nothing to distinguish the Canteen Kopje Skull from other modern, pre-European skulls, and conclude that the skull is probably of no great antiquity. The skull has undergone some re-mineralization, but it is now understood that this can be a quite rapid process, indeed modern palaeontologists generally suspect that most preserved bones are re-mineralized quite soon after burial, with bones that do not undergo this process decaying within a few years.

3D tomogram reconstructions of the Canteen Kopje Skull, the curly object inside the skull is a bent metal bar supporting the plaster matrix. From Smith et al. (2012)

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