A new method of sexing juvenile human remains has recently been described in the literature (Parker et al. 2019, Stewart et al. 2017, Stewart et al. 2016), and it sounds almost too good to be true: sexually dimorphic amelogenin protein fragments can be identified in human enamel using high performance liquid chromatography.
Based on morphology alone, it is notoriously difficult to assign sex to children, as sexual dimorphism develops primarily after puberty. Osteologists therefore do not normally assign sex to children and adolescents under the age of about 16 to 18 (Cunningham, Scheuer, and Black 2016). In recent years, DNA analysis has been employed to determine the genetic sex of skeletons, but DNA analysis is destructive, its success depends on the preservation of the nuclear DNA and the costs are still prohibitive. The identification of peptides in tooth enamel, in contrast, is almost non-destructive – it only needs an incredibly small amount of tooth enamel gained by acid etching of a small area of the surface of the tested tooth. The tested area is hardy visible to the naked eye (wearing contact lenses, I could not see it).
As an archaeologists interested in age and gender, this is like a (slightly macabre) dream come true. We can finally answer a number of questions on sex-specific mortality patterns, on sex-preferences, and demography. Why is knowing the sex of buried children so important? We will be able to know if sex selection took place after birth and whether infanticide affected more girls or more boys. We can ask whether girls and boys were treated equally as babies and small children, for example in terms of access to food. We can investigate if children of both sexes were afforded the same burial rites. We will be able to tell if the sex of babies and infants was important, or if societies only responded to the differences between girls and boys later, as children matured. We will be much better able to understand how children ‘learn gender’, at what age girls and boys were socially recognized and treated as adolescents and adults. In summary, we can learn a lot about value systems linked to gender, about power relationships between the sexes, and about how they developed in past societies.
It is a lucky coincidence that Fabian Kanz, my collaboration partner in Forensic Medicine, has good contacts to the Department of Analytical Chemistry of the University in Vienna, where nanoLCMS/MS machines are part of the routine analytical equipment. Thanks to the efforts of Lukas Janker and Dina Schuster, a test on a series of modern deciduous and permanent teeth from individuals with known sex was successful, a laboratory protocol was established, and work on prehistoric teeth could begin. The first sex identification of a 5-6-year-old Bronze Age child via peptides in tooth enamel produced unambiguous results, as AMELY was clearly present. It’s a boy!
Cunningham, C., L. Scheuer, and S. Black. 2016. Developmental Juvenile Osteology, 2nd edition. London: Elsevier Academic.
Parker, G. J., J. M. Yip, J. W. Eerkens, M. Salemi, B. Durbin-Johnson, C. Kiesow, R. Haas, J. E. Buikstra, H. Klaus, L. A. Regan, D. M. Rocke, and B. S. Phinney. 2019. Sex estimation using sexually dimorphic amelogenin protein fragments in human enamel. Journal of Archaeological Science 101: 169-180.
Stewart, N. A., R. F. Gerlach, R. L. Gowland, K. J. Gron, and J. Montgomery. 2017. Sex determination of human remains from peptides in tooth enamel. Proceedings of the National Academy of Sciences.
Stewart, N. A., G. F. Molina, J. P. Mardegan Issa, N. A. Yates, M. Sosovicka, A. R. Vieira, S. R. P. Line, J. Montgomery, and R. F. Gerlach. 2016. The identification of peptides by nanoLC-MS/MS from human surface tooth enamel following a simple acid etch extraction. RSC Advances 6, 66: 61673-61679.