The first Turner syndrome patient lived in the Iron Age, while the first Jacobs syndrome patient dates back to the Early Middle Ages. This was revealed by a group of English scientists from the Francis Crick Institute, authors of a study published in 'Communications Biology', conducted together with colleagues from the universities of Oxford and York and Oxford Archaeology. Thanks to a new technique that allows the number of chromosomes in ancient genomes to be 'counted' more precisely, these 'DNA archaeologists' have discovered the first 6 sufferers with too many or too few chromosomes. In addition to the 2 with Turner syndrome (only one X chromosome instead of 2) and Jacobs syndrome (an extra Y chromosome, therefore an who lived in different periods and a child with Down syndrome (3 chromosomes 21), also from the Iron Age.
Most cells in the human body, all except gametes (egg and sperm), have 23 pairs of chromosomes: 22 homologous pairs and one XX (in the female) or XY (in the male) pair. When cells have one more or one less chromosome, we speak of aneuploidy: precisely the genetic anomaly identified by the authors in the cases described by analyzing data collected in the scope of the Thousand Ancient British Genomes project. The 6 'patient ancestors' were identified in 5 sites between Somerset, Yorkshire, Oxford and Lincoln, who lived over a period of time ranging from the Iron Age (2,500 years ago) to the Post Middle Ages (about 250 years ago).
The 5 people with a composition of sex chromosomes different from the canonical XX or The 3 Klinefelter patients, although from very different eras, shared some similarities: they were all slightly taller than average and showed signs of delayed development during puberty. Regarding the Turner syndrome sufferer, examining her bones, scholars believe it is unlikely that she entered puberty and started menstruating, despite an estimated age of 18-22 years. The researchers also observed that she suffered from a form of Turner's disease called 'mosaic', with some cells having only one X chromosome and others having two.
“Through the precise measurement of sex chromosomes – says Kakia Anastasiadou, PhD student at the Crick Institute's Ancient Genomics Laboratory and first author of the study – we were able to provide the first prehistoric evidence of Turner syndrome dating back 2,500 years, and the first known evidence of Jacob's syndrome, about 1,200 years ago. It is difficult to draw a complete picture of how these people lived and interacted with society, since they were not found with particular possessions or buried in unusual graves”, but by analyzing from the available findings it is possible to obtain “some information on how the perception of gender identity has evolved over time”.
“Our method – underlines Pontus Skoglund, head of the Ancient Genomics Laboratory of the Crick Institute – is also able to classify the contamination suffered by DNA and can help analyze incomplete ancient DNA, so it could be applied to archaeological remains that are difficult to examine. Combining this data with the context of the burial and possessions will also allow us to understand how sex, gender and diversity were perceived in past societies. I hope that this type of approach will be applied as it grows the availability of ancient DNA” to investigate.
For Rick Schulting, professor of scientific and prehistoric archeology at the University of Oxford, “the results of this work open up new and exciting possibilities for the study of sex in the past, moving beyond binary categories in a way that would be impossible without the progress made in the analysis of ancient DNA”.
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