Jebel Irhoud is a cave site located about 100 km west of Marrakech, Morocco. The site is known for the numerous hominin fossils discovered there. Currently, the site has yielded seven specimens. The best known of these are portions of two adult skulls, Irhoud 1 and 2, a child’s mandible (Irhoud 3), and a child’s humerus (Irhoud 4). Fossils 1-3 were discovered while the cave was being quarried for barytes and thus their exact context and age has been subject to debate. Originally the Irhoud hominins were considered North African Neandertals. It is now clear that they are best grouped with other early anatomically modern humans such as Qafzeh (Israel) and Skhul (Israel).
The industry associated with the deposits is clearly Middle Stone Age with Levallois technology and the fauna looks to be late Middle or early Upper Pleistocene. An initial attempt at radiocarbon dating showed the site to be beyond the limit of this technique. In 1991, Grun and Stringer reported ESR dates on three mammal teeth from a layer overlying the Irhoud 4 fossil. The results have a very large range and depending on which uranium uptake model is used could span from 90 to 190 thousand years ago.
The exact date of these fossils has become more important in the context of the “Out of Africa” model of modern human origins. It is currently suggested that modern humans had their origin in Africa sometime in the last 200,000 years. If the ESR dates are correct and particularly if one accepts the earliest dates, then the Jebel Irhoud hominins are amongst the oldest anatomically modern humans in Africa.
In May of 2004, the department along with the Institut National des Sciences de l’Archéologie et du Patrimoine (INSAP, Rabat, Morocco) started a new project at Jebel Irhoud. This work began with a short season to identify the remaining in situ deposits and to assess the feasibility of conducting new excavations. It was determined that only a limited column of in situ deposits with archaeological materials remained.
Since 2004 we have conducted several one month long field seasons in an effort to re-excavate and date the complete sequence. This work has produced a new map of the site, identified likely sources of raw material for the Middle Stone Age industries there, obtained new samples of these stone tool industries from the entire sequence, obtained new dating samples of heated flint, identified several in situ fire features, and identified the brecciated lower levels from which the previously recovered fossil hominins likely derive.
Additionally, in the 2007 season and in subsequent seasons, new hominin material was discovered near the base of the sequence. We are currently processing and analyzing the material collected during the last field seasons. Several publications are under preparation. The next field season is currently planned for late 2013 or early 2014.
A new study of the Irhoud 3 mandible was published in 2007 by Tanya Smith, Jean-Jacques Hublin and colleagues. This work shows that this individual was approximately 8 years old at death and showed a stage of development similar to modern European children of the same age. The implications are that this early Homo sapiens showed a modern human pattern of growth and development and likely experience a similarly prolonged childhood.
Smith, T.M., Tafforeau, P.T., Reid, D.J., Grün, R., Eggins, S., Boutakiout, M. & Hublin, J.-J. (2007) Earliest evidence of modern human life history in North African early Homo sapiens. Proc. Natl. Acad. Sci. USA 104:6128-6133. [pdf]