Letters to Nature
Nature 414, 628-631 (6 December 2001) | doi:10.1038/414628a; Received 13 July 2001; Accepted 1 October 2001
Growth processes in teeth distinguish modern humans from Homo erectus and earlier hominins
Christopher Dean1, Meave G. Leakey2, Donald Reid3, Friedemann Schrenk4, Gary T. Schwartz5, Christopher Stringer6 & Alan Walker7
- Evolutionary Anatomy Unit, Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
- Department of Palaeontology, National Museums of Kenya, PO Box 40658, Nairobi, Kenya
- Oral Biology, Dental School, Framlington Place, Newcastle upon Tyne NE2 4BW, UK
- Forschungsinstitut Senckenberg, Palaeanthropologie, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany
- Department of Anthropology, The George Washington University, 2110 G Street, NW, Washington DC 20052, USA
- Human Origins Group, Department of Palaeontology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
- Anthropology Department, 409 Carpenter Building, Pennsylvania State University, University Park, Pennsylvania 16802, USA
Correspondence to: Christopher Dean1 Correspondence and requests for materials should be addressed to C.D. (e-mail: Email: ucgacrd@ucl.ac.uk).
A modern human-like sequence of dental development, as a proxy for the pace of life history, is regarded as one of the diagnostic hallmarks of our own genus Homo
1, 2, 3. Brain size, age at first reproduction, lifespan and other life-history traits correlate tightly with dental development4, 5, 6. Here we report differences in enamel growth that show the earliest fossils attributed to Homo do not resemble modern humans in their development. We used daily incremental markings in enamel to calculate rates of enamel formation in 13 fossil hominins and identified differences in this key determinant of tooth formation time. Neither australopiths nor fossils currently attributed to early Homo shared the slow trajectory of enamel growth typical of modern humans; rather, both resembled modern and fossil African apes. We then reconstructed tooth formation times in australopiths, in the 
1.5-Myr-old Homo erectus skeleton from Nariokotome, Kenya7, and in another Homo erectus specimen, Sangiran S7-37 from Java8. These times were shorter than those in modern humans. It therefore seems likely that truly modern dental development emerged relatively late in human evolution.
