Sunday 26 August 2018

Human teeth from the Middle Stone Age layers of the Magubike Rockshelter of Tanzania.

The Magubike Rockshelter is located in the Iringa Rural (or Iringa Vijijini), District in the Iringa Region in the southern Highlands of Tanzania. It was discovered in 2005, when Iron Age artifacts, including ceramics, domesticated animal bones and iron tools, were observed at the surface. A series of excavations at the site from 2006 revealed the presence of a Later Stone age layer beneath the Iron Age layer, and beneath this a Middle Stone Aged layer, with flake tools made on radial or discoidal cores associated with the Levallois technology. A number of dating methods have been used on these deposits, thought with limited success, probably due to water peculating through the site, though the Middle Stone Aged layers are thought to be at least 45 000 years old, and probably considerably older.

In a paper published in the journal PLoS One on 31 July 2018, Pamela Willoughby of the Department of Anthropology at the University of Alberta, Tim Compton and Silvia Bello of the Department of Earth Sciences at the Natural History Museum, Pastory Bushozi of the Department of History and Archaeology at the University of Dar es Salaam, Anne Skinner of the Department of Chemistry at Williams College, and Chris Stringer, also of the Department of Earth Sciences at the Natural History Museum, describe a series of Human teeth derived from the Middle Stone Age layer at the Magubike Rockshelter.

 The Magubike Rockshelter in the Iringa Rural District of the Iringa Region in the southern Highlands of Tanzania. Willoughby et al. (2018).

The Middle Stone Age of Africa is lasted from around 280 000 years ago to between 50 and 25 000 years ago. It is associated with the Levallois technology, in which the chips derived from a central core are themselves used as cutting tools, which the core is retained as a source of material rather than being used as a tool in itself, and with both anatomically Modern Humans and some archaic forms.

Morphometric analysis is a tool used by palaeontologists, archaeologists, anthropologists and forensic pathologists to analyse and compare specimens. It relies on taking numerous measurements of an object such as a bone or shell, and comparing both these measurements and ratios between measurements to those obtained from other specimens in order to establish relationships between them.  

The teeth recovered from the Magubike Rockshelter comprise six permanent, fully developed upper teeth, these being the left and right central incisors, right lateral incisor, right canine, right third premolar and left fourth premolar. They were not all found together, but rather in two groups separated vertically by about 10 cm of sediment, but are considered to be from the same individual, as they all show the same level of ware, are from an individual of the same age (roughly 15-16 years) and there are no duplicate teeth.

Photos of the labial, mesial, lingual, distal and occlusal surfaces of the Magubike teeth: Upper left central (LCI), right central (RCI) and right lateral (RLI) incisors, right canine (RC) and right third premolar (RP3) and left fourth premolar (LP4). Scale bar is 1cm. Willoughby et al. (2018).

Willoughby et al. compared the Magubike teeth to Middle Pleistocene Homo heidelbergensis and archaic Homo sapiens teeth and Middle and Late Pleistocene Modern Homo sapiens teeth from a variety of sites in Africa, Early and Middle Holocene East and Southern African sites, and recent teeth from Southern Africa.

Of these samples the Magubike teeth were found to most closely resemble those of modern San individuals from Southern Africa. This is surprising, as while genetic studies have suggested that the San have existed as a distinct genetic lineage for a very long time, and San-like skeletal remains have been found associated with Late Stone Age sites in Tanzania, all skeletal Modern Human remains found associated with Middle Stone Age technologies to date have belonged to a taller, unSan-like population.

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