Earliest evidence of modern human life history in North African early Homo sapiens
- Tanya M. Smith*,†,
- Paul Tafforeau‡,§,
- Donald J. Reid¶,
- Rainer Grün‖,
- Stephen Eggins‖,
- Mohamed Boutakiout**, and
- Jean-Jacques Hublin*
- *Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany;
- ‡Laboratoire de Géobiologie, Biochronologie et Paléontologie Humaine, Unité Mixte de Recherche 6046, Centre National de la Recherche Scientifique, Université de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France;
- §European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, 38046 Grenoble Cedex, France;
- ¶Department of Oral Biology, School of Dental Sciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4BW, United Kingdom;
- ‖Research School of Earth Sciences, Australian National University, Canberra ACT 0200, Australia; and
- **Department of Geology, Faculty of Sciences, University Mohammed V-Agdal, Avenue Ibn Battouta, BP 1014, Rabat, Morocco
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Communicated by Richard G. Klein, Stanford University, Stanford, CA, February 1, 2007 (received for review December 12, 2006)
Abstract
Recent developmental studies demonstrate that early fossil hominins possessed shorter growth periods than living humans, implying disparate life histories. Analyses of incremental features in teeth provide an accurate means of assessing the age at death of developing dentitions, facilitating direct comparisons with fossil and modern humans. It is currently unknown when and where the prolonged modern human developmental condition originated. Here, an application of x-ray synchrotron microtomography reveals that an early Homo sapiens juvenile from Morocco dated at 160,000 years before present displays an equivalent degree of tooth development to modern European children at the same age. Crown formation times in the juvenile's macrodont dentition are higher than modern human mean values, whereas root development is accelerated relative to modern humans but is less than living apes and some fossil hominins. The juvenile from Jebel Irhoud is currently the oldest-known member of Homo with a developmental pattern (degree of eruption, developmental stage, and crown formation time) that is more similar to modern H. sapiens than to earlier members of Homo. This study also underscores the continuing importance of North Africa for understanding the origins of human anatomical and behavioral modernity. Corresponding biological and cultural changes may have appeared relatively late in the course of human evolution.
Footnotes
- †To whom correspondence should be addressed at: Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany. E-mail: tsmith{at}eva.mpg.de
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Author contributions: T.M.S., P.T., and J.-J.H. designed research; T.M.S., P.T., D.J.R., R.G., and S.E. performed research; M.B. and J.-J.H. contributed new reagents/analytic tools; T.M.S., P.T., and D.J.R. analyzed data; and T.M.S., P.T., R.G., S.E., and J.-J.H. wrote the paper.
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↵ ††In this article, early H. sapiens includes African fossils postdating 200,000 ybp that are variably referred to as “ancestors of modern humans,” “early anatomically modern humans,” or “early modern humans” (1–6).
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The authors declare no conflict of interest.
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See Commentary on page 6093.
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This article contains supporting information online at www.pnas.org/cgi/content/full/0700747104/DC1.
- Abbreviations:
- Phase contrast SR-mCT,
- Phase contrast X-ray synchrotron microtomography;
- ybp,
- years before present.
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Freely available online through the PNAS open access option.
- © 2007 by The National Academy of Sciences of the USA
