This method in sex determination may revolutionise what we know about the past
We are often hindered in archaeology and forensic anthropology as we cannot safely determine sex in infants and children using non-ancient DNA (aDNA) techniques, leaving much of our understanding about a myriad of aspects of gender and health untouched. The methods we have for infant and child sex estimation that use size and shape of the skeletal remains are not sensitive enough to assess sex differences until after puberty. Using ancient DNA analysis to determine sex is also problematic due to preservation and contamination issues, as well as its destructive and costly nature. Although there have been attempts of aDNA sex determination of purported infanticide victims from Romano-British sites, they have been severely limited to sampling very small proportions of the infants at the sites.
A new study published in the Proceedings of the National Academy of Sciences has presented an exciting method that can determine the sex of human remains more easily and with minimal destruction of precious archaeological samples. By using tiny samples through a process of surface acid etching of tooth enamel they have shown that they can identify sex chromosome-linked isoforms (proteins that have a similar but not identical amino acid sequences) of amelogenin, an enamel-forming protein, by a form of specialised mass spectrometry. A mass spectrum, in simple terms, measures the masses and therefore the chemical characteristics of a sample.
Tooth enamel is the hardest tissue in the human body due to its high mineral content and is therefore best preserved in the burial environment. This study used archaeological samples from the UK spanning from over 5,000 years ago until the 19th century, and found that in all cases the sex determined using this new method agreed with the assignment of sex by either coffin plates or other osteological techniques.
This study is a game changer for archaeology and forensics, which will allow many avenues for research that have been hitherto untouched, and will be of particular value in the burgeoning field of the study of children in the past. With knowledge of sex we will be able to explore, for the first time, gender-based practices in care, infanticide, diet, as well as start to tease apart the nuances of differences in health and growth between male and female infants and children in archaeological samples.