Combining radiographic and histological data for dental development to compare growth in the past and the present

Abstract

Background: Being able to estimate the age at death of fossil hominins enables meaningful comparisons of both dental and general growth, past and present.

Aim: The aim of this study was to use data for modern permanent canine formation derived from separate histological and radiographic studies to estimate the age at death of an early African Homo erectus specimen (KNM-WT 15 000) with a developing permanent maxillary canine.

Methods: Ground sections of 18 sexed modern human canines were used to reconstruct growth in tooth height along the enamel–dentine junction (EDJ) and onwards into root formation along the cement–dentine junction (CDJ). Daily rates of enamel and dentine formation were used to put a time scale to cumulative fractions of tooth height.

Results: Age estimates for KNM-WT 15 000 averaged 7.89–8.8 years of age (range = 6.6–10.3 years) and were close to previous histological estimates for this individual (7.6–8.8 years).

Conclusions: Stages of dental development in KNM-WT 15 000 were easily accommodated within this age distribution of a modern sample. However, body mass and stature estimates for KNM-WT 15 000 fell well beyond those reported for a modern sample of 438 Sudanese children aged between 7.0–10 years.

• Canines
• dentine
• dental development
• enamel
• hominin
• Homo erectus
• radiography

Acknowledgements

We thank Sarah Elton and Kevin Kuykendall and the organizers of the SSHB Symposium, “Human Biology of the Past”, held in Durham, August 2013, for inviting us to take part and present a paper where aspects of the study reported here were first discussed. We thank Dr Emma Mbua, The National Museums of Kenya, Nairobi, The Government of Kenya, Dr Felista Mangalu and the National Natural History Museum in Arusha, Tanzania, and the Tanzania Commission for Science and Technology (COSTECH) for previously granting one of us (MCD) permission to study precious fossil material in their care. We thank Richard Pilley and Neil Shah for enabling various clinical aspects of this study and we are especially grateful to two referees who made detailed and insightful comments that greatly improved the manuscript.