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. 2007 Apr 10;104(15):6128-33.
doi: 10.1073/pnas.0700747104. Epub 2007 Mar 19.

Earliest evidence of modern human life history in North African early Homo sapiens

Tanya M Smith  1 , Paul Tafforeau, Donald J Reid, Rainer Grün, Stephen Eggins, Mohamed Boutakiout, Jean-Jacques Hublin
Affiliations

Earliest evidence of modern human life history in North African early Homo sapiens

Tanya M Smith et al. Proc Natl Acad Sci U S A. .

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.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.
Fig. 1.
Unerupted lower left canine germ of the Irhoud 3 juvenile. (A) Stereo microscope overview with position of area enlarged in B (white box) and virtual plane of section in C (dotted line). (B) Perikymata (white arrows), surface manifestations of long-period Retzius lines, were counted from the cusp tip to the cervix on the original tooth. (C) Cuspal enamel thickness (white line near top) and estimated root length (dotted line near bottom) were taken from this virtual section. Labial root length estimate was made by projecting the curvatures of the developing root cone and the enamel-dentine junction. (Scale bars: 2 mm in A and C and 0.2 mm in B.)
Fig. 2.
Fig. 2.
Enamel microstructure in an incisor fragment from Irhoud 3. (A) Virtual section (70 μm thick) of labial enamel generated by using phase contrast SR-mCT. (Scale bar: 0.5 mm.) (B–D) The enlarged areas from top to bottom show daily cross-striations (light and dark bands crossing diagonal enamel prisms) in the lateral enamel (B), the periodicity of Retzius lines: 10 daily cross-striations (small arrows) between successive Retzius lines (large arrows) (C) (see also SI Fig. 7), and an area of cervical enamel showing accentuated lines and slight prism decussation (D).
Fig. 3.
Fig. 3.
The mandibular dentition of the Irhoud 3 juvenile; crowns are in white, roots in yellow. (A and B) Virtual mandible showing the dentition from anterior (A) and lateral (B) perspectives, with the dentition virtually extracted in situ on the right. (C) Isolated and virtually extracted teeth in labial/buccal orientation on the left and occlusal orientation on the right (teeth left to right: right lateral incisor, left canine, left first premolar, left second premolar, left first permanent molar, left second permanent molar). Bright white speckles are from a dense mineral that invaded the mandible during fossilization. (Scale bars: 2 cm.)
See this image and copyright information in PMC

Comment in

  • Growing up slowly 160,000 years ago.
    Dean C. Dean C. Proc Natl Acad Sci U S A. 2007 Apr 10;104(15):6093-4. doi: 10.1073/pnas.0701317104. Epub 2007 Apr 2. Proc Natl Acad Sci U S A. 2007. PMID: 17404213 Free PMC article. No abstract available.

References

    1. Hublin J-J. In: Human Roots. Barham L, Robson-Brown K, editors. Bristol, UK: Western Academic and Specialist; 2001. pp. 99–121.
    1. Klein R. The Human Career. Chicago: University of Chicago; 1999.
    1. McBrearty S, Brooks A. J Hum Evol. 2000;39:453–563. - PubMed
    1. White TD, Asfaw B, DeGusta D, Gilbert H, Richards GD, Suwa G, Howell FC. Nature. 2003;423:742–747. - PubMed
    1. McDougall I, Brown FH, Fleagle JG. Nature. 2005;433:733–736. - PubMed

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